Engineering

"For the benefit of all."

"The Congress hereby declares that it is the policy of the United States that activities in space should be devoted to peaceful purposes for the benefit of all mankind."

"To improve life here. To extend life to there. To find life beyond."

"To understand and protect our home planet, To explore the universe and search for life, To inspire the next generation of explorers."

"Shaping the Future: Launching New Endeavors to Inspire the Next Generation of Explorers."

"Since 1970 or thereabouts going to space has not been part of our national agenda. NASA has kept complete control over space. But since 1970 NASA has produced paper, not spaceships."

"NASA, the National Aeronautics and Space Administration. Where else but in Texas would men set up to administer space?"

"We lack any sort of device that can... detect life. We don't have a life meter. ...We don't have a general pupose life meter that can detect life as we don't know it. Obviously, if it's life as we know it, there are all sorts of features. ...NASA plans a mission to... ... which has a plume of organic material spewing out, and they want to fly through that plume... The question is, what are they going to put onboard that would return a result "Yes, we have found life"... How would you do that? What exactly do you measure?"

"It [Traveling to Mars] is important for our future. If the dinosaurs had a space program, they'd still be here."

"There's been a lot of discussion about NASA culture and changing that. I think our culture has always been one of trying to do a very difficult job and do it well."

"HERE MEN FROM THE PLANET EARTH FIRST SET FOOT UPON THE MOON JULY 1969, A.D. WE CAME IN PEACE FOR ALL MANKIND."

"Well, today physicists peering into the infinitely small realms of subatomic particles find reaffirmations of religious faith. Astronomers build a space telescope that can see to the edge of the universe and possibly back to the moment of creation. So, yes, this nation remains fully committed to America's space program. We're going forward with our shuttle flights. We're going forward to build our space station. And we are going forward with research on a new Orient Express that could, by the end of the next decade, take off from Dulles Airport, accelerate up to 25 times the speed of sound, attaining low Earth orbit or flying to Tokyo within 2 hours. And the same technology transforming our lives can solve the greatest problem of the 20th century. A security shield can one day render nuclear weapons obsolete and free mankind from the prison of nuclear terror. America met one historic challenge and went to the Moon. Now America must meet another: to make our strategic defense real for all the citizens of planet Earth."

"With Artemis missions, NASA will land the first woman and first person of color on the Moon, using innovative technologies to explore more of the lunar surface than ever before. We will collaborate with commercial and international partners and establish the first long-term presence on the Moon. Then, we will use what we learn on and around the Moon to take the next giant leap: sending the first astronauts to Mars."

"We’re going back to the Moon for scientific discovery, economic benefits, and inspiration for a new generation of explorers: the Artemis Generation. While maintaining American leadership in exploration, we will build a global alliance and explore deep space for the benefit of all."

"We will build an Artemis Base Camp on the surface and the Gateway in lunar orbit. These elements will allow our robots and astronauts to explore more and conduct more science than ever before."

"All that we build, all that we study, all that we do, prepares us to go."

"OUR SUCCESS WILL CHANGE THE WORLD"

"To be overwhelmingly clear, we did not stretch out our timeline or delay anything. What we did is insert additional missions, standardized, so we can actually achieve the national policy that President Trump set out to return American astronauts to the Moon, and build an enduring presence to stay. Artemis II, we're going to launch in a matter of weeks [and] go around the Moon," Isaacman explained. "Artemis III will launch by mid 2027 with the aim to buy down risk and low Earth orbit for subsequent [Moon] landing attempts in 2028."

"We're going to get there in steps, continue to take down risk as we learn more and we roll that information into subsequent designs. We've got to get back to basics."

"Good design is a Renaissance attitude that combines technology, cognitive science, human need and beauty to produce something."

"The urge for good design is the same as the urge to go on living. The assumption is that somewhere, hidden, is a better way of doing things."

"As a noun, design is the named (although sometimes unnamable) structure or behavior of a system whose presence resolves or contributes to the resolution of a force or forces on that system. A design thus represents one point in a potential decision space. A design may be singular (representing a leaf decision) or it may be collective (representing a set of other decisions)."

"When any great design thou dost intend, Think of the means, the manner, and the end."

"Disguise and complication are hindrances, both to good construction and good design, and as complication and disguise are expensive and wasteful... the interests of good art and true economy run on parallel lines."

"As in poetry and music, even the unskilled ear may be offended by a mistake in measure, without discerning the cause, may not also a mistake in the harmony of dimensions unconsciously offend us in design?"

"One of the best ways to economize in building is to economize on ugliness. ...Nothing can be greater service in avoiding ugliness than a knowledge of the principles of design."

"If the chief rules of good design were understood by the masses as they might be, nothing would do more to promote beauty, improve workmanship, add to the value of manufactures, and in many other ways further the general welfare and prosperity of the country. They are simple, easy to acquire, and should be taught with the alphabet."

"Giannino Castiglioni was a sculptor. His work was realistic, always tied to the human figure, not fantastic or unreal. He had an attitude of constant analysis of people's characteristics."

"They float before my soul, the fair designs Which I would body forth to Life and Power, Like clouds, that with their wavering hues and lines Pourtray majestic buildings:—"

"Design is to design a design to produce a design."

"Honest designs Justly resemble our devotions, Which we must pay, and wait for the reward."

"I consider my father a proto-designer."

"I think so many of the objects we're surrounded by seem trivial. And I think that's because they're either trying to make a statement or trying to be overtly different. What we were trying to do was have a very honest approach and an exploration of materials and surface treatment. So much of what we try to do is get to a point where the solution seems inevitable: you know, you think 'of course it's that way, why would it be any other way?' It looks so obvious, but that sense of inevitability in the solution is really hard to achieve."

"The more I learnt about this cheeky — almost rebellious — company, the more it appealed to me, as it unapologetically pointed to an alternative in a complacent and creatively bankrupt industry. Apple stood for something and had reason for being that wasn't just about making money."

"People think it's this veneer — that the designers are handed this box and told, 'Make it look good!' That's not what we think design is. It's not just what it looks like and feels like. Design is how it works."

"I think that designers have an incredibly broad creative repertoire. They solve. They create images of perfection for any number of clients. I could never do that. I’m my client. That’s the difference between an artist and a designer; it’s a client relationship. And so, to me, it’s not a hierarchical order; it’s not like artists are better than designers, but it is a particular instrumentality, which makes for a difference."

"I think this will be as good a pattern for orders as I can think on. A little thin flowery border round, neat not gaudy, and the Drury Lane Apollo with the harp at the top."

"In a very real way, designers create the human environment; they make the things we use, the places we live and work, our modes of communication and mobility. Simply put, design matters. And at a moment in our history in which the scientific community has issued serious warnings about the negative impacts of our flawed designs-from global warming and water pollution to the loss of biodiversity and natural resources-designers have a critical role to play in the creation of a more just, healthful and sustainable world."

"Design is redesign."

"If you want a golden rule that will fit everybody, this is it: Have nothing in your houses that you do not know to be useful, or believe to be beautiful."

"Good design is also an act of communication between the designer and the user, except that all the communication has to come about by the appearance of the device itself. The device must explain itself."

"In their work, designers often become expert with the device they are designing. Users are often expert at the task they are trying to perform with the device. [...] Innocence lost is not easily regained. The designer simply cannot predict the problems people will have, the misinterpretations that will arise, and the errors that will get made."

"There is a lot of modeling in my work, also because I am the son of Giannino Castiglioni, a sculptor, and I have always seen my father working with his hands, shaping material to gradually give it the desired form."

"The design process involves a series of operations. In map design, it is convenient to break this sequence into three stages. In the first stage, you draw heavily on imagination and creativity. You think of various graphic possibilities, consider alternative ways..."

"Good design looks right. It is simple (clear and uncomplicated). Good design is also elegant, and does not look contrived. A map should be aesthetically pleasing, thought provoking, and communicative"

"This is exactly the meaning of design: the conflict between form and content, form being the problem. [...] It is the coming together of form and content that is the realization of design."

"Always design a thing by considering it in its next larger context—a chair in a room, a room in a house, a house in an environment, an environment in a city plan."

"I have always believed that fashion was not made only to make women more beautiful, but also to reassure them, give them confidence."

"Everyone designs who devises courses of action aimed at changing existing situations into preferred ones. The intellectual activity that produces material artefacts is no different fundamentally from the one that prescribes remedies for a sick patient or one that devises a new sales plan for a company or a social welfare policy for a state. Design, so construed, is the core of all professional training; it is the principal mark that distinguishes the professions from the sciences. Schools of engineering, as well as schools of architecture, business, education, law, and medicine are all centrally concerned with the process of design."

"Today, the problem is not to produce more so you can sell more. The fundamental question is that of the product's right to exist. And it is the designer's right and duty, in the first place, to question the legitimacy of the product, and that is how he too comes to exist. Depending on what answer he comes up with, one of the most positive things a designer can do is refuse to do anything,"

"From a structural point of view, design is totally useless... I tried to give my products a little sense and energy. But even when I gave the best of myself, it was absurd."

"It appears that all the students who enter the school commence as if they were intended for artists in the higher sense of the word, and are not expected to decide as to whether they will devote themselves to the Fine Arts or to Industrial Design, until after they have completed their exercises in the drawing and painting of the figure from the antique and from the living model. It is for this reason, and from the fact that artists for industrial purposes are both well-paid and highly considered (as being well-instructed men), that so many individuals in France engage themselves in both pursuits."

"Paris, Vienna, Berlin, and, we may now say, London, together with many other cities in which periodical Exhibitions of Industrial Art take place, have not, as yet, any appropriate edifice - for these Exhibitions, but some temporary erection or already - existing building is fitted up for the purpose. When the multitude of productions as impose the necessity of an especial erection, it has been necessarily attended with great expense, which is the more objectionable since it is destined to be removed after a very brief existence. The King of Bavaria has been the first to see the necessity of an edifice constructed solely for Exhibitions of Industrial Art, and has, accordingly, caused to be erected a suitable building, of which we are enable to present an engraving. It was inaugurated on the 25th of last August, the King's birthday."

"Fine Art then, records by idealised imitation the glorious works of good men, whilst it holds those of bad men up to our abhorrence — it gives to posterity their images, either on the tinted canvass or the sculptured marble — it imitates the beautiful effects of nature as seen in the glowing landscape or the rising storm, and perpetuates the appearance of those beauteous gems of the seasons — flowers and fruits, which, though fading whilst the painter catches their tints, yet live after decay by and through his genius. Industrial Art, on the contrary, aims at the embellishment of the works of man, by and through that power which is given to the artist for the investigation of the beautiful in nature; and in transferring it to the loom, the printing machine, the potter's wheel, or the metal worker's mould, he reproduces nature in a new form, adapting it to his purpose by an intelligence arising out of his knowledge as an artist and as a workman. In short, the adaptation of the natural type to a new material compels him to reproduce, almost create, as well as imitate — invent as well as copy — design as well as draw!"

"INDUSTRIAL DESIGN is destined to become a universal language ; for in our material age of rapid transition, from abstract, to applied, Science — in the midst of our extraordinary tendency towards the perfection of the means of conversion, or manufacturing production — it must soon pass current in every land."

"The study of Industrial Design is really as indispensably necessary as the ordinary rudiments of learning. It ought to form an essential feature in the education of young persons for whatever profession or employment they may intend to select, as the great business of their lives; for without a knowledge of drawing, no scientific work, whether relating to Mechanics, Agriculture, or Manufactures, can be advantageously studied."

"The triumph of the industrial arts will advance the cause of civilization more rapidly than its warmest advocates could have hoped, and contribute to the permanent prosperity and strength of the country far more than the most splendid victories of successful war."

"In treating the subject a purpose has been kept in view, viz., to try to explain the principles involved in certain methods employed for the production of ornament, and this in order to guide the industrial designer to sure and certain results. To be successful the processes involved in the production of articles of manufacture must be understood, and to this the earnest attention of all interested in the improvement of manufacture should be directed. The abstract teaching of design is comparatively valueless, and success will only be achieved when to the taste of the designer the skill of the workman is united."

"Let us, then, take care of that art which is intended to penetrate into the houses of the lowly. In doing this we may rest assured, that that which is intended to embrace a more exalted position will not be forgotten. Let us not lose tight of the sentiment to nobly expressed by the poet — blind yet bold — when he says:—"

"It has been well observed that the world, more especially the English portion of it, during the last half century, has been in its working dress; that is to say, although we have done some very wonderful things in the way of mechanics, and have produced other things which are marvels of cheapness, yet as regards the production of really beautiful objects, particularly those required in every-day life, we have been behind most other epochs of civilization. Of course there is no prima facie reason why cheap things should be ugly, for a die or mould of a good design costs no more than a bad one; but still the fact remains that the objects in use in every-day life are not beautiful, and it is to effect a change in this respect that the Government have established Schools of Design and the excellent Museum of which I shall have to speak hereafter. Great praise must also be given to the Society of Arts for beginning the movement and carrying it on to the present time; and although the sphere of its action must necessarily be infinitely smaller than that of the Government Schools, yet we should always remember that the initiative of our great English exhibitions of industry came from the Society, and that it is to those exhibitions that we owe the stirring among the dry bones of industrial art which is now taking place."

"At the suggestion of the publishers, this work was undertaken to form one of their series of Dictionaries and Cyclopeadias. In this view, it has been the intention to make it a complete course of instruction and book of reference to the mechanic, architect and engineer. It has not, therefore, been confined to the explanation and illustration of the methods of projection, and the delineation of objects which might serve as copies to the draughtsman, matters of essential importance for the correct and intelligible representation of every form; but it contains the means of determining the amount and direction of strains to which different parts of a machine or structure may be subjected, and the rules for disposing and proportioning of the material employed, to the safe and permanent resistance of those strains, with practical applications of the same."

"The plan of the books is the first systematic effort made in this country to cover the whole field of Art Education for schools, by embracing every subject included under the head of Elementary Drawing. Pupils going through the course in all the subjects will be thoroughly grounded, and prepared either for practical industrial art or the further professional study of the fine arts."

"This question of industrial design is nearly distinct from the general Art education of the public, the former being very much a manufacturers' undertaking, while the other, being of the first importance, appeals to the community at large for sympathy and support."

"Our industrial design is very bad still — a great deal of it — though infinitely better than it was thirty years ago. So a great deal of our teaching of design may be, I fear is, unsound; but all the sound teaching we have is through such schools as this, and even in our errors there is, let us hope, instruction."

"The only way of reaping a harvest of good industrial design is by sowing the seed of good Art."

"The subject of industrial design is one of three important practical co-related subjects which should be taught in public schools, and to which practice and skill in drawing should be applied. Satisfactory results in this subject, however, depend entirely upon the manner in which it is taught. Instruction in industrial design means a clear presentation of the principles which obtain in the construction and harmonious arrangement of geometric form for decorative purposes, the proper use of plant forms in ornamental arrangements, and the principles of good taste to be found in the great history styles of art."

"There are many branches of manufacturing industry which greatly depend for their success upon the designer's art, and it is necessary that the industrial designer should possess a knowledge of the processes of the manufacture in which his designs will be utilized, as well as of the properties and capabilities of the material to which they will be applied."

"The course in industrial design is as follows: First year: Free-hand drawing — Drawing in outline from the flat, from groups of geometrical solids, from objects, memory drawing. Industrial design — Geometrical and free-hand designing in flat outline, historical ornament (ancient) . Mechanical drawing — Elementary perspective, practical geometry. Mathematics — Mensuration, ^first year), Euclid, book 1 (one term only). Second year Free-hand drawing — Drawing in light and shade from the flat and model, from groups of geometrical solids, from ornamental casts, from objects, memory drawing. Industrial design — Designing from plant forms in outline (flat), elementary color (flat), historical ornament (medieval). Third year: Free-hand drawing — Continuation of work of second year, drawing in monochrome, memory drawing. Industrial design — Plastic design, historical ornament (modern), history of design, clay modeling. Work in the special courses is intended largely to supplement the work done in the regular course, but it is of a much more practical nature."

"As architecture stands for parent design principles and represents some of the world's best examples of composition and design, industrial design should be based upon the best examples of architectural design."

"The designer of today, in most branches of art and particularly in the field of industrial design, needs more than vision and inspiration. This can be seen easily by anyone who will trouble himself to analyze the motif of some costly production and consider its chance to endure on the basis of artistic worth, rather than mere excellence of technical finish."

"In brief the industrial designer is a fashion designer of industrial products and is called upon by industry and manufacturers to "style" their products or to "streamline" them."

"Modern industrial design has advanced at a rapid pace during the last ten years. Its successes are no longer confined to objects which, like automobiles and airplanes, are themselves the product of new conditions. Modern design has also begun to conquer the traditional arts, and the feeling for abstract form, first expressed in our time in the works of Picasso, Braque, Brancusi, Duchamps-Villon in Europe, or Stieglitz, Benton, and Storrs for example in the United States, has finally entered architecture and the decorative arts."

"Modern industrial design is based on the principle of conspicuous economy [but] the bourgeois culture which dominates the Western World is founded... on the principle of conspicuous waste."

"One of the functions of an industrial designer is to bridge the gap between manufacturer and ultimate buyer."

"This book is aimed primarily at the young person making his choice of a vocation. It is also designed to give business executives and engineers a clear idea of how the industrial designer operates, what he can do for their business, and how much to expect from him after he has been engaged."

"The industrial designer is found in many fields of industry, which represent a wide diversity of manufactured products. Some of these fields are: Automobiles, airplanes, boats, trains, trailers, trucks; vacuum cleaners, washing machines, toasters, electric fans, lamps; furniture, hardware, electrical equipment; china, glassware, pottery; silverware; garden implements; farm machinery; tools of all kinds;"

"Industrial design is not necessary in the production of goods; but it makes goods more acceptable."

"A most important element for the consideration of the industrial designer is sales. There is only one reason for hiring an industrial designer, and that is to increase the sales of a product."

"In speaking and thinking of industrial design, care must be taken not to limit its application to the few obvious trades. Industrial design is important to every industry and its value in most hast already been demonstrated."

""Can we afford industrial design?" "Is the industrial design consultant merely a stylist ?" "Does the employment of a designer tend to raise the standard of design?" These questions leap to the mind. My friend, , Honorary r.d.i., has gone to a great deal of trouble in his answers to these questions..."

"Industrial design keeps the customer happy, his client in the black and the designer busy."

"A lot of people are open to new things, as long as they look like the old ones."

"There are professions more harmful than industrial design, but only a very few of them. And possibly only one profession is phonier. Advertising design, in persuading people to buy things they don’t need, with money they don’t have, in order to impress others who don’t care, is probably the phoniest field in existence today. Industrial design, by concocting the tawdry idiocies hawked by advertisers, comes a close second. Never before in history have grown men sat down and seriously designed electric hairbrushes, rhinestone-covered file boxes, and mink carpeting for bathrooms, and then drawn up elaborate plans to make and sell these gadgets to millions of people. Before (in the “good old days”), if a person liked killing people, he had to become a general, purchase a coal mine, or else study nuclear physics. Today, industrial design has put murder on a mass production basis. By designing criminally unsafe automobiles that kill or maim nearly one million people around the world each year, by creating whole new species of permanent garbage to clutter up the landscape, and by choosing materials and processes that pollute the air we breathe, designers have become a dangerous breed."

"If there is a designer whose name is synonymous with industrial design it is Raymond Loewy (1893-1986)."

"What Charles and Ray Eames are to furniture design, Raymond Loewy is to industrial design—the modern master"

"Manufacturers are realizing that good industrial design is an important ingredient in their products' success and a vital factor in industrial competitiveness in both domestic and international markets."

"Industrial design is a big industry, so there are always new businesses opening up that have really exciting opportunities."

"If we think about things having multiple lives, cradle to cradle, we could design things that can go back to either nature or back to industry forever."

"Industrial design had its origins in the Industrial Revolution, when factory production began to supplant craft production of housewares, textiles, tools, and other consumer goods."

"Anything that can be automatically done for you can be automatically done to you."

"Besides black art, there is nothing left in the United States but automation and mechanization."

"As the bourgeoisie, by means of its capital, completely monopolizes all new inventions, every new machine, instead of shortening the hours of labor and enhancing the prosperity and happiness of all, causes, on the contrary, dismissal from employment for some, reduction of wages for others and an increased and intensified state of misery for the entire proletariat."

"Where you have machines, then you get certain kinds of problems; where you get certain kinds of problems, then you find a heart warped by these problems. Where you get a heart warped, its purity and simplicity are disturbed. When purity and simplicity are disturbed, then the spirit is alarmed and an alarmed spirit is no place for the Tao to dwell. It isn't that I don't know of these machines, but I would be ashamed to use one."

"If every instrument could accomplish its own work, obeying or anticipating the will of others, [...]; if, in like manner, the shuttle would weave and the plectrum touch the lyre without a hand to guide them, chief workmen would not want servants, nor masters slaves."

"AI and robots will replace all jobs."

"(About Amazon's plan to automate 75% of its operations) It’s insane to think that a human will pack and ship boxes in ten years — it’s game over folks."

"In the short term, AI will destroy a lot of jobs. In In the long term, like every other technological revolution, I assume we will figure out completely new things to do."

"If you eventually get a society where you only have to work three days a week, that’s probably OK. If you free up human labor, you can help elder people better, have smaller class sizes – you know, the demand for labor to do good things is still there. And then if you ever get beyond that, you have a lot of leisure time and you’ll have to figure out what to do with it."

"There’s going to be more free time. If you believe the premise that humans are social animals, they’re going to have to do something. They can’t just sit at home, so they’ll go to music, they’ll go to sports and they’ll go to my live event."

"According to the theory of aerodynamics, as may be readily demonstrated through wind tunnel experiments, the bumblebee is unable to fly. This is because the size, weight and shape of his body in relation to the total wingspread make flying impossible. But the bumblebee, being ignorant of these scientific truths, goes ahead and flies anyway—and makes a little honey every day."

"For I dipt into the future far as human eye could see, Saw the Vision of the world, and all the wonder that would be; Saw the heavens fill with commerce, argosies of magic sails, Pilots of the purple twilight, dropping down with costly bales; Heard the heavens fill with shouting, and there rain'd a ghastly dew From the nations' airy navies grappling in the central blue."

"Let brisker youths their active nerves prepare Fit their light silken wings and skim the buxom air."

"He rode upon a cherub, and did fly: yea, he did fly upon the wings of the wind."

"Wal, I like flyin' well enough," He said, "but the' ain't sich a thundern' sight O' fun in't when ye come to light."

"Darius was clearly of the opinion That the air is also man's dominion And that with paddle or fin or pinion, We soon or late shall navigate The azure as now we sail the sea."

"The birds can fly, an' why can't I? Must we give in," says he with a grin, "That the bluebird an' phœbe are smarter 'n we be?"

"[Engineering concerns] the creative application of scientific principles to design or develop structures, machines, apparatus, or manufacturing processes, or works utilizing them singly or in combination; or to construct or operate the same with full cognizance of their design; or to forecast their behavior under specific operating conditions; all as respects an intended function, economics of operation and safety to life and property.""

"As with anything else, there are good and bad ways to forecast."

"Psychologist Philip Tetlock (following the lead of Isaiah Berlin), divided the world of political forecasters into hedgehogs and foxes."

"If you make a great number of predictions, the ones that were wrong will soon be forgotten, and the ones that turn out to be true will make you famous."

"Question 8. Is There a Measurable, Qualitatively Distinctive Prediction of String Theory? String theories can, in principle, make many "s" (such as the calculation of the mass ratios of s and s, Higgs masses and couplings, s, etc.). They can also make many new predictions (such as the masses of the supersymmetric partners of the observed particles, new gauge interactions, etc.). These would be sufficient to establish the validity of the theory, however in each case one can imagine (although with some difficulty) conventinal field theories coming up with similar pre or post dictions. It would be nice to predict a phenomenon, which would be accessible at observable energies and is uniquely characteristic of string theory."

"I have always believed that people have misjudged the accuracy of economic forecasting... During the 1980s and 1990s, I researched and applied methods of high frequency economic forecasting, to be used by themselves, and for objective establishment of initial conditions for longer range forecasts from structural dynamic models that carry forward the pioneering contributions of Jan Tinbergen."

"A forecast can only be based on a diagnosis about current trends if it is to be based on something other than wishful thinking. This is why I was never a strong supporter of the distinction between forecasts and projections: our best forecasts are intelligent projections. Moreover, it turns out that learning about the diagnosis that underlies a forecast is often much more rewarding than learning about the forecast itself."

"Dynamic systems studies usually are not designed to predict what will happen. Rather, they're designed to explore what would happen, if a number of driving factors unfold in a range of different ways."

"I am profoundly skeptical about our abilities to predict the future in general, and human behavior in particular."

"Without precise predictability, control is impotent and almost meaningless. In other words, the lesser the predictability, the harder the entity or system is to control, and vice versa. If our universe actually operated on linear causality, with no surprises, uncertainty, or abrupt changes, all future events would be absolutely predictable in a sort of waveless orderliness."

"The only function of economic forecasting is to make astrology look respectable."

"Forecasting by bureaucrats tends to be used for anxiety relief rather than for adequate policy making."

"This led me to the thought that it might be easy to pretend to be a Seer. After all, if one pretended to have visions of the far distant future, how would anyone know if they came true or not?"

"The intellectually aggressive hedgehogs knew one big thing and sought, under the banner of parsimony, to expand the explanatory power of that big thing to “cover” new cases; the more eclectic foxes knew many little things and were content to improvise ad hoc solutions to keep pace with a rapidly changing world."

"It is my hope that in such a way we may again, as Marx claimed, find scientific arguments in the competition between various systems, but up-to-date scientific arguments rather than obsolete ones. This more fundamental research in economics deserves relatively more attention and resources than the more superficial versions of economic research directed at forecasting or analysing very short-term fluctuations in market prices, on which quite some money is being spent to-day."

"The successes of modern control theory in the design of highly accurate space navigation systems have stimulated its use in the theoretical analyses of economic and biological systems. Similarly, the effectiveness of computer simulation techniques in the macroscopic analyses of physical systems has brought into vogue the use of computer-based econometric models for purposes of forecasting, economic planning, and management."

"Prediction is very difficult, especially about the future."

"Incorrigible humanity, therefore, led astray by the giant Nimrod, presumed in its heart to outdo in skill not only nature but the source of its own nature, who is God; and began to build a tower in Sennaar, which afterwards was called Babel (that is, 'confusion'). By this means human beings hoped to climb up to heaven, intending in their foolishness not to equal but to excel their creator."

"Only among those who were engaged in a particular activity did their language remain unchanged; so, for in­stance, there was one for all the architects, one for all the carriers of stones, one for all the stone-breakers, and so on for all the different opera­tions. As many as were the types of work involved in the enterprise, so many were the languages by which the human race was fragmented; and the more skill required for the type of work, the more rudimentary and barbaric the language they now spoke. But the holy tongue remained to those who had neither joined in the project nor praised it, but instead, thoroughly disdaining it, had made fun of the builders' stupidity."

"When I looked at the science of engineering and saw that it had disappeared after its ancient heritage, that its masters have perished, and that their memories are now forgotten, I worked my wits and thoughts in secrecy about philosophical shapes and figures, which could move the mind, with effort, from nothingness to being and from idleness to motion. And I arranged these shapes one by one in drawings and explained them"

"[Engineering concerns] the creative application of scientific principles to design or develop structures, machines, apparatus, or manufacturing processes, or works utilizing them singly or in combination; or to construct or operate the same with full cognizance of their design; or to forecast their behavior under specific operating conditions; all as respects an intended function, economics of operation and safety to life and property.""

"As an engineer, he knew that a bucket-load of philosophical principles wasn’t worth a grain of good hard fact."

"Engineers do not particularly like PR men."

"The civil engineer is the real 19th century architect."

"Engineers should press forward with development to meet the diversified needs of people"

"A good scientist is a person with original ideas. A good engineer is a person who makes a design that works with as few original ideas as possible. There are no prima donnas in engineering."

"I was originally supposed to become an engineer but the thought of having to expend my creative energy on things that make practical everyday life even more refined, with a loathsome capital gain as the goal, was unbearable to me."

"There are two laws discrete, Not reconciled,— Law for man, and law for thing; The last builds town and fleet, But it runs wild, And doth the man unking."

"Engineering is the conscious application of science to the problem of economic production."

"The metalworker encourages the goldsmith, and the one who smooths with the hammer spurs on the one who strikes the anvil. One says of the welding, “It is good.” The other nails down the idol so it will not topple."

"It is a fight to the death between Big Oil and everybody else. Everybody else will benefit from HSR (high speed rail). It cleans up the air. It opens up all kind of new possibilities where you can live a more affordable life and get jobs further away...Everyone is going to benefit, except the oil industry, and that’s where the problem is.... There are some major changes needed to our transportation sector, which means that we need to electrify it. That will mean a whole lot of work for engineers...This is a huge project that the engineering profession needs to step up and be the leaders on. It’s not just an opportunity that means lots of jobs. It means the engineering profession gets to be front and center when solving this humongous problem that everyone looks at as almost unsolvable. It’s not unsolvable. It’s very solvable."

"The world needs more engineers willing to solve problems and fewer rich philosophers who have run out of ways to spend money."

"Engineering is too important to wait for science."

"A good engineer is always a wee bit conservative, at least on paper."

"Architects and engineers are among the most fortunate of men since they build their own monuments with public consent, public approval and often public money."

"As a guide to engineering ethics, I should like to commend to you a liberal adaptation of the injunction contained in the oath of Hippocrates that the professional man do nothing that will harm his client. Since engineering is a profession which affects the material basis of everyone’s life, there is almost always an unconsulted third party involved in any contact between the engineer and those who employ him — and that is the country, the people as a whole. These, too, are the engineer’s clients, albeit involuntarily. Engineering ethics ought therefore to safeguard their interests most carefully. Knowing more about the public effects his work will have, the engineer ought to consider himself an “officer of the court” and keep the general interest always in mind."

"The transition to renewable energy can be greatly accelerated if the world’s governments finally bring the engineers to the fore... I was recently on a panel with three economists and a senior business-sector engineer. After the economists spoke... the engineer spoke succinctly and wisely. “I don’t really understand what you economists were just speaking about, but I do have a suggestion... Tell us engineers the desired ‘specs’ and the timeline, and we’ll get the job done.” This is not bravado.... The next big act belongs to the engineers. Energy transformation for climate safety is our twenty-first-century moonshot."

"A key characteristic of the engineering culture is that the individual engineer’s commitment is to technical challenge rather than to a given company. There is no intrinsic loyalty to an employer as such. An employer is good only for providing the sandbox in which to play. If there is no challenge or if resources fail to be provided, the engineer will seek employment elsewhere. In the engineering culture, people, organization, and bureaucracy are constraints to be overcome. In the ideal organization everything is automated so that people cannot screw it up. There is a joke that says it all. A plant is being managed by one man and one dog. It is the job of the man to feed the dog, and it is the job of the dog to keep the man from touching the equipment. Or, as two Boeing engineers were overheard to say during a landing at Seattle, “What a waste it is to have those people in the cockpit when the plane could land itself perfectly well.” Just as there is no loyalty to an employer, there is no loyalty to the customer. As we will see later, if trade-offs had to be made between building the next generation of “fun” computers and meeting the needs of “dumb” customers who wanted turnkey products, the engineers at DEC always opted for technological advancement and paid attention only to those customers who provided a technical challenge."

"A man should build a house with his own hands before he calls himself an engineer."

"Engineers simply refuse to eliminate a thing they call “safety factor.” They will deliberately over-design and over-build by a factor ranging from two to ten, depending upon the magnitude and seriousness of the consequences if something goes wrong. This does not mean that they have no confidence in their work. It is their statement of reality because they know good and well that sooner or later (a) somebody is going to goof, forget instructions, panic, or try to stretch the design, and/or (b) something in the system is going to malfunction."

"Engineering: The art of organizing and directing men, and of controlling the forces and materials of nature for the benefit of the human race."

"Any job I do—if it doesn’t work, somebody pays. Possibly hundreds or thousands of somebodies. That’s the price of good engineering; nobody notices you did your job right."

"Comparatively few engineers are good mathematicians; and... it is fortunate that such is the case; for nature rarely combines high mathematical talent, with that practical tact, and observation of outward things, so essential to a successful engineer. There have been... brilliant exceptions; but they are very rare. But few even of those who have been tolerable mathematicians when young, can, as they advance in years, and become engaged in business, spare the time necessary for retaining such accomplishments."

"Engineering is the art of directing the great sources of power in nature for the use and convenience of man."

"These experiences are not 'religious' in the ordinary sense. They are natural, and can be studied naturally. They are not 'ineffable' in the sense the sense of incommunicable by language. Maslow also came to believe that they are far commoner than one might expect, that many people tend to suppress them, to ignore them, and certain people seem actually afraid of them, as if they were somehow feminine, illogical, dangerous. 'One sees such attitudes more often in engineers, in mathematicians, in analytic philosophers, in book keepers and accountants, and generally in obsessional people'. The tends to be a kind of bubbling-over of delight, a moment of pure happiness. 'For instance, a young mother scurrying around her kitchen and getting breakfast for her husband and young children. The sun was streaming in, the children clean and nicely dressed, were chattering as they ate. The husband was casually playing with the children: but as she looked at them she was suddenly so overwhelmed with their beauty and her great love for them, and her feeling of good fortune, that she went into a peak experience . . ."

"Cybernetics: or Control and Communication in the Animal and the Machine"

"The machines of which we are now speaking are not the dream of the sensationalist,nor the hope of some future time. They alreadyexist as thermostats, automatic gyro-compass ship-steering systems, self-propelled missiles – especially such as seek their target – anti aircraft fire-control systems, automatically controlled oil-crackingstills, ultra-rapid computing machines, and the like. They had begun to be used long before the war – indeed, the very old steam-engine governor belongs among them –but the great mechanization of the Second World War brought them into their own,and the need of handling the extremely dangerous energy of the atom will probably bring them to a still higher point of development. . .the present age is as truly the age of the servomechanisms as the nineteenth century was the age of the steam engine or the eighteenth century the age of the clock."

"The concepts of purposive behavior and teleology have long been associated with a mysterious, self-perfecting or goal-seeking capacity or final cause, usually of superhuman or super-natural origin. To move forward to the study of events, scientific thinking had to reject these beliefs in purpose and these concepts of teleological operations for a strictly mechanistic and deterministic view of nature. This mechanistic conception became firmly established with the demonstration that the universe was based on the operation of anonymous particles moving at random, in a disorderly fashion, giving rise, by their multiplicity, to order and regularity of a statistical nature, as in classical physics and gas laws. The unchallenged success of these concepts and methods in physics and astronomy, and later in chemistry, gave biology and physiology their major orientation. This approach to problems of organisms was reinforced by the analytical preoccupation of the Western European culture and languages. The basic assumptions of our traditions and the persistent implications of the language we use almost compel us to approach everything we study as composed of separate, discrete parts or factors which we must try to isolate and identify as potential causes. Hence, we derive our preoccupation with the study of the relation of two variables. We are witnessing today a search for new approaches, for new and more comprehensive concepts and for methods capable of dealing with the large wholes of organisms and personalities."

"The concept of teleological mechanisms however it be expressed in many terms, may be viewed as an attempt to escape from these older mechanistic formulations that now appear inadequate, and to provide new and more fruitful conceptions and more effective methodologies for studying self-regulating processes, self-orienting systems and organisms, and self-directing personalities. Thus, the terms feedback, servomechanisms, circular systems, and circular processes may be viewed as different but equivalent expressions of much the same basic conception"

"… Norbert Wiener of the Massachusetts Institute of Technology, a brilliant mathematician who recently won fame with his invention of cybernetics, a new science of communications... His prolonged studies of the striking analogies between the control systems in animal bodies and those in complex machines became the basis of his newly created cybernetics, a science of communications."

"CYBERNETICS. Catch on to this word now. It's a new coined to label the fast-growing electronic brain system of industry which mat have more effect on the way we live than will atomic energy."

"The celebrated physicist and mathematician A.M. Ampere coined the word cybernetique to mean the science of civil government (Part II of "Essai sur la philosophic des sciences", 1845, Paris). Ampere's grandiose scheme of political sciences has not, and perhaps never will, come to fruition. In the meantime, conflict between governments with the use of force greatly accelerated the development of another branch of science, the science of control and guidance of mechanical and electrical systems. It is thus perhaps ironical that Ampere's word should be borrowed by N. Wiener to name this new science, so important to modern warfare. The "cybernetics" of Wiener ("Cybernetics, or Control and Communication in the animal and the Machine," John Wiley & Sons, Inc., New York, 1948) is the science of organization of mechanical and electrical components for stability and purposeful actions. A distinguishing feature of this new science is the total absence of considerations of energy, heat, and efficiency, which are so important in other natural sciences. In fact, the primary concern of cybernetics is on the qualitative aspects of the interrelations among the various components of a system and the synthetic behavior of the complete mechanism."

"Naturally there are detailed differences in messages and in problems of control, not only between a living organism and a machine, but within each narrower class of beings. It is the purpose of Cybernetics to develop a language and techniques that will enable us indeed to attack the problem of control and communication in general, but also to find the proper repertory of ideas and techniques to classify their particular manifestations under certain concepts."

"Cybernetics is likely to reveal a great number of interesting and suggestive parallelisms between machine and brain and society. And it can provide the common language by which discoveries in one branch can readily be made use of in the others... [There are] two peculiar scientific virtues of cybernetics that are worth explicit mention. One is that it offers a single vocabulary and a single set of concepts suitable for representing the most diverse types of system... The second peculiar virtue of cybernetics is that it offers a method for the scientific treatment of the system in which complexity is outstanding and too important to be ignored. Such systems are, as we well know, only too common in the biological world!"

"Cybernetics is one of the youngest sciences in the world. Generally speaking, it was born in 1948, when the American mathematician Norbert Wiener, the pioneer of modern cybernetics, published a book under that title. The name soon became a fashion in the West, where even science is an object of fashion. Cybernetics, as such, is a concept that dates back many, many centuries. In ancient Greece it meant the art of steering, the skill of sailing ships — a skill so highly esteemed in that land of seafaring people that there were special festivities in its honour. In 1834 the famous French scientist Andre Ampere classified 128 branches of science, among which he named cybernetics as the science of steering, alongside with others for which he invented names. Wiener, thus, did not think up a new name. He simply applied the old one to a modern science."

"[Cybernetics is] the art of ensuring the efficacy of action."

"The word 'cybernetics' is still new to many people, even though it has now been an accepted word of our language for some ten or fifteen years. Speaking generally, cybernetics is the scientific study of control and communication. It is an attempt to give an integrated account of both physical and biological systems in terms of their capacity to communicate between different points of the system, and in terms of their control. There has been considerable research into general methods of communication in recent years, and this has been primarily the work of communication engineers, who are trying to discover in general terms what they themselves are doing."

"Cybernetics is the science of the process of transmission, processing and storage of information."

"For Stafford Beer, cybernetics was ‘the science of which operational research is the method’: ‘The representation and analysis of real world processes using logic, mathematics and computer science’, Operations Research (OR) and its offspring Systems Analysis (SA) transformed the manner in which war was prepared for, planned and imagined."

"All this (the early excitement of Cybernetics) is now history, and in the decade which elapsed since these early baby steps of interdisciplinary communication, many more threads were picked up and interwoven into a remarkable tapestry of knowledge and endeavour: Bionics. It is good omen that at the right time the right name was found. For, bionics extends a great invitation to all who are willing not to stop at the investigation of a particular function or its realization, but to go on and to seek the universal significance of these functions in living or artificial organisms. The reader who goes through the following papers which constitute the transactions of the first symposium held under the name Bionics will be surprised by the multitude of astonishing and unforeseen connections between concepts he believed to be familiar with. For instance, a couple of years ago, who would have thought to relate the reliability problem to multi-valued logics; or, who would have thought that integral or differential geometry would serve as an adequate tool in the theory of abstraction? It is hard to say in all these cases who was teaching whom: The life-sciences the engineering sciences, or vice versa? And rightly so, for it guarantees optimal information flow, and everybody gains..."

"Cybernetics is still headline news, and increasingly we hear about its applications to new fields of scientific and industrial endeavour. Stafford Beer's new book Cybernetics and Management is an admirable account on the relation that exist between cybernetics and the problems of management in industry [and]... covers a range of applications that have not previously been dealt with in print."

"Cybernetics is the general science of communication. But to refer to communication is consciously or otherwise to refer to distinguishable states of information inputs and outputs and /or to information being processed within some relatively isolated system."

"Cybernetics is concerned primarily with the construction of theories and models in science, without making a hard and fast distinction between the physical and the biological sciences. The theories and models occur both in symbols and in hardware, and by 'hardware* we shall mean a machine or computer built in terms of physical or chemical, or indeed any handleable parts. Most usually we shall think of hardware as meaning electronic parts such as valves and relays. Cybernetics insists, also, on a further and rather special condition that distinguishes it from ordinary scientific theorizing: it demands a certain standard of effectiveness. In this respect it has acquired some of the same motive power that has driven research on modern logic, and this is especially true in the construction and application of artificial languages and the use of operational definitions. Always the search is for precision and effectiveness, and we must now discuss the question of effectiveness in some detail. It should be noted that when we talk in these terms we are giving pride of place to the theory of automata at the expense, at least to some extent, of feedback and information theory."

"A great deal of the thinking [in Organizational Development] has been influenced by cybernetics and information theory, though this has been used as much to extend the scope of as to improve the sophistication of formulations. It was von Bertalanffy (1950) who, in terms of the general transport equation which he introduced, first fully disclosed the importance of openness or closedness to the environment as a means of distinguishing living organisms from inanimate objects."

"In 1946, a Macy Foundation interdisciplinary conference was organized to use the model provided by "feedback systems," honorifically referred to in earlier conferences as "teleological mechanisms," and later as "cybernetics," with the expectation that this model would provide a group of sciences with useful mathematical tools and, simultaneously, would serve as a form of cross-disciplinary communication. Out of the deliberations of this group came a whole series of fruitful developments of a very high order. Kurt Lewin (who died in 1947) took away from the first meeting the term "feedback". He suggested ways in which group processes, which he and his students were studying in a highly disciplined, rigorous way, could be improved by a "feedback process," as when, for example, a group was periodically given a report on the success or failure of its particular operations."

"If cybernetics is the science of control, management is the profession of control"

"Cybernetics is the science or the art of manipulating defensible metaphors; showing how they may be constructed and what can be inferred as a result of their existence."

"As an anthropologist, I have been interested in the effects that the theories of Cybernetics have within our society. I am not referring to computers or to the electronic revolution as a whole, or to the end of dependence on script for knowledge, or to the way that dress has succeeded the mimeographing machine as a form of communication among the dissenting young. Let me repeat that, I am not referring to the way that dress has succeeded the mimeographing machine as a form of communication among the dissenting young. I specifically want to consider the significance of the set of cross-disciplinary ideas which we first called “feed-back” and then called “teleological mechanisms” and then called it “cybernetics,” a form of crossdisciplinary thought which made it possible for members of many disciplines to communicate with each other easily in a language which all could understand."

"As Alain Enthoven was himself to recognize, ‘you assume that there is an information system that will tell you what you want to know. But that just isn’t so. There are huge amounts of misinformation and wronginformation’. Thus, far from eliminating the Clausewitzian ‘fog of war’, cybernetic warfare itself generated ‘a kind of twilight, which, like fog or moonlight, often tends to make things seem grotesque and larger than they really are’."

"Perhaps the most important single characteristic of modern organizational cybernetics is this: That in addition to concern with the deleterious impacts of rigidly-imposed notions of what constitutes the application of good "principles of organization and management" the organization is viewed as a subsystem of a larger system(s), and as comprised itself of functionally interdependent subsystems."

"The theory of information became the cornerstone of cybernetics because the latter deals with "the study of systems of any nature that are capable of receiving, storing and processing information and utilizing it for control"."

"The meaning of the term "cybernetics" is today somewhat different from that used when Wiener, McCulloch, Rosenblueth, Bigelow and others used the Greek word "Kybernetes," or helmsmen, to describe an automatic computer... the definition, which I first gave in 1966: "Cybernetics describes an intelligent activity or event which can be expressed in algorithms. Algorithms, in turn, refer to a system of instructions which describes unambiguously and accurately an interaction which is equivalent to a given type of flux of intelligence and a subsequent, controlled activity. The development of cybernetics aims, among other things, at the design and reproduction of functions which are peculiar to intelligent organism.""

"The essence of cybernetic organizations is that they are self-controlling, self-maintaining, self-realizing. Indeed, cybernetics has been characterized as the “science of effective organization,” in just these terms. But the word “cybernetics” conjures, in the minds of an apparently great number of people, visions of computerized information networks, closed loop systems, and robotized man-surrogates, such as “artorgas” and “cyborgs.”"

"Another scientific development that we find difficult to absorb into our traditional value system is the new science of cybernetics: machines that may soon equal or surpass man in original thinking and problem-solving. [...] In the hands of the present establishment there is no doubt that the machine could be used – is being used – to intensify the apparatus of repression and to increase established power. But again, as in the issue of population control, misuse of science has often obscured the value of science itself. In this case, though perhaps the response may not be quite so hysterical and evasive, we still often have the same unimaginative concentration on the evils of the machine itself, rather than a recognition of its revolutionary significance."

"Now "cybernetics" is the term coined by Wiener to denote "steersmanship" or the science of control. Although current engineering usage restricts it to the study of flows in closed systems, it can be taken in a wider context, as the study of processes interrelating systems with inputs and outputs, and their structural-dynamic structure. It is in this wider sense that "cybernetics" will be used here, to wit, as system-cybernetics, understanding by "system" an ordered whole in relation to its relevant environment (hence one actually or potentially open)."

"The main object of cybernetics is to supply adaptive, hierarchical models, involving feedback and the like, to all aspects of our environment. Often such modelling implies simulation of a system where the simulation should achieve the object of copying both the method of achievement and the end result. Synthesis, as opposed to simulation, is concerned with achieving only the end result and is less concerned (or completely unconcerned) with the method by which the end result is achieved. In the case of behaviour, psychology is concerned with simulation, while cybernetics, although also interested in simulation, is primarily concerned with synthesis. Most of the major developments in models and theories of artificial intelligence have taken place in the western world — mostly, indeed, in the US and Britain — and it was only relatively recently that "core developments", as opposed to more peripheral developments and applications, have spread over Europe and the Soviet Union."

"During the 1950s and 1960s most of the work which was called cybernetics tended to focus on control systems in engineering or on applications of the concept of feedback in fields ranging from mathematics to sociology. At the 1970 meeting of the American Society for Cybernetics in Philadelphia Heinz von Foerster sought to redirect attention to the original interests which had led to the founding of the field of cybernetics. In a paper titled "Cybernetics of Cybernetics" he made a distinction between first order cybernetics, the cybernetics of observed systems, and second order cybernetics, the cybernetics of observing systems."

"The cybernetics phase of cognitive science produced an amazing array of concrete results, in addition to its long-term (often underground) influence:"

"Think about the technology of sports footwear," she says. "Before the Civil War, right and left feet weren't even differentiated in shoe manufacture. Now we have a shoe for every activity." Winning the Olympics in the cyborg era isn't just about running fast. It's about "the interaction of medicine, diet, training practices, clothing and equipment manufacture, visualization and timekeeping." When the furor about the cyborgization of athletes through performance-enhancing drugs reached fever pitch last summer, Haraway could hardly see what the fuss was about. Drugs or no drugs, the training and technology make every Olympian a node in an international technocultural network just as "artificial" as sprinter Ben Johnson at his steroid peak."

"From the start, the cyborg was more than just another technical project; it was a kind of scientific and military daydream. The possibility of escaping its annoying bodily limitations led a generation that grew up on Superman and Captain America to throw the full weight of its grown-up R&D budget into achieving a real-life superpower. By the mid-1960s, cyborgs were big business, with millions of US Air Force dollars finding their way into projects to build exoskeletons, master-slave robot arms, biofeedback devices, and expert systems. For all the big bucks and high seriousness, the prevailing impression left by old cyborg technical papers is of a rather expensive kind of science fiction. Time and again, scientific reasoning melts into metaphysical speculation about evolution, human boundaries, and even the possibility of what Clynes and Kline call "a new and larger dimension for man's spirit." The cyborg was always as much a creature of scientific imagination as of scientific fact. It wasn't only the military that was captivated by the possibilities of the cyborg. The dream of improving human capabilities through selective breeding had long been a staple of the darker side of Western medical literature. Now there was the possibility of making better humans by augmenting them with artificial devices. Insulin drips had been used to regulate the metabolisms of diabetics since the 1920s. A heart-lung machine was used to control the blood circulation of an 18-year-old girl during an operation in 1953. A 43-year-old man received the first heart pacemaker implant in 1958. By the 1970s, the idea of an augmented human had entered the mainstream. Steve Austin, The Six Million Dollar Man, and his cohort Jaime Sommers, The Bionic Woman (with bionic limbs and a super-sensitive bionic ear), were popular heroes, their custom superpowers bought off the shelf like a digital watch. The cyborg had grown from a lecture-room fantasy into the stuff of prime-time TV."

"Wiener's dream of a universal science of communication and control has faded with the years. Cybernetics has given rise to new areas like cognitive science and stimulated valuable research in numerous other fields. But almost no one today calls themselves a cyberneticist. Some believe that Wiener's project fell victim to scientific fashion, its funding sucked away by flashy but ultimately pointless AI research. Others think cybernetics was killed by the basic problem that the nuts-and-bolts mechanisms of control and communication in machines are significantly different from those in animals, and neither are very like control and communication in society. So cybernetics, which was based on an inspired generalization, fell victim to its inability to deal with details. Whichever perspective is true (and as with most such stories, the truth is likely to be a mixture of both), cybernetics has left two important cultural residues behind. The first is its picture of the world as a collection of networks. The second is its intuition that there's not as much clear blue water between people and machines as some would like to believe. These still-controversial concepts are at the bionic heart of the cyborg, which is alive and well, and constructing itself in a laboratory near you."

"An opportunity for cybernetics to change the course of the philosophy of mind was missed when intentionality was misinterpreted as "the providing of coded knowledge"."

"Many of the core ideas of cybernetics have been assimilated by other disciplines, where they continue to influence scientific developments. Other important cybernetic principles seem to have been forgotten, though, only to be periodically rediscovered or reinvented in different domains. Some examples are the rebirth of neural networks, first invented by cyberneticists in the 1940's, in the late 1960's and again in the late 1980's; the rediscovery of the importance of autonomous interaction by robotics and AI in the 1990's; and the significance of positive feedback effects in complex systems, rediscovered by economists in the 1990's. Perhaps the most significant recent development is the growth of the complex adaptive systems movement, which, in the work of authors such as John Holland, Stuart Kauffman and Brian Arthur and the subfield of , has used the power of modern computers to simulate and thus experiment with and develop many of the ideas of cybernetics. It thus seems to have taken over the cybernetics banner in its mathematical modelling of complex systems across disciplinary boundaries, however, while largely ignoring the issues of goal-directedness and control."

"Cybernetics is the study of systems and processes that interact with themselves and produce themselves from themselves."

"Since the 1960s, Japan has produced a considerable number of cyborg narratives in manga and anime, particularly in works targeting male children and adolescents. From early manga examples such as Kazumasa Hirai and Hiro Kuwata's 8 Man and Shotaro Ishinomori's Cyborg 009, and their subsequent anime versions, the protagonist is commonly cyborged against their will or desires. This positions them as victims, regardless of how physically powerful they are. Their sense of inferiority and vulnerability usually underpins these narratives, either subtly or explicitly. The depiction of female cyborgs adds complexity to the positioning of cyborgs in manga and anime, especially in terms of gender. Female cyborgs may be equipped with remarkable physical strength, combined with voluptuous, eroticized bodies (for instance Major Motoko Kusanagi in Masamune Shirow's original manga and Mamoru Oshii's anime version of Ghost in the Shell); and these powerful female cyborgs are also frequently ascribed roles as protectors or supporters of incompetent and insecure male protagonists. Although some female cyborgs may possess characteristics that indicate a transgression of the conventional boundaries of gender, this transgression is often limited and undermined by other elements of their depiction. As Kumiko Sato points out in her essay "How Information Technology Has "Not, Changed Feminism and Japanism", "female cyborgs and androids have been domesticated and fetishized into maternal and sexual protectors of the male hero" and thus "their functions is usually reduced to either a maid or a goddess obediantly serving her beloved male master, the sole reason for her militant nature.""

"For me, as I later came to say, cybernetics is the art of creating equilibrium in a world of possibilities and constraints. This is not just a romantic description, it portrays the new way of thinking quite accurately. Cybernetics differs from the traditional scientific procedure, because it does not try to explain phenomena by searching for their causes, but rather by specifying the constraints that determine the direction of their development."

"In the late 1950s, experiments such as the cybernetic sculptures of Nicolas Schöffer or the programmatic music compositions of John Cage and Iannis Xenakis transposed systems theory from the sciences to the arts. By the 1960s, artists as diverse as , Hans Haacke, Robert Morris, Sonia Sheridan, and were breaking with accepted aesthetics to embrace open systems that emphasized organism over mechanism, dynamic processes of interaction among elements, and the observer’s role as an inextricable part of the system. Jack Burnham’s 1968 Artforum essay “Systems Aesthetics” and his 1970 “Software” exhibition marked the high point of systems-based art until its resurgence in the changed conditions of the twenty-first century."

"Cyborg. The word has a whiff of the implausible about it that leads many people to discount it as mere fantasy. Yet cyborgs, real ones, have been among us for almost 50 years. The world's first cyborg was a white lab rat, part of an experimental program at New York's Rockland State Hospital in the late 1950s. The rat had implanted in its body a tiny osmotic pump that injected precisely controlled doses of chemicals, altering various of its physiological parameters. It was part animal, part machine."

"The '90s cyborg is both a more sophisticated creature than its '50s ancestor - and a more domestic one. Artificial hip joints, cochlear implants for the deaf, retinal implants for the blind, and all kinds of cosmetic surgery are part of the medical repertoire. Online information retrieval systems are used as prosthetics for limited human memories. In the closed world of advanced warfare, cyborg assemblages of humans and machines are used to pilot fighter aircraft - the response times and sensory apparatus of unaided humans are inadequate for the demands of supersonic air combat. These eerie military cyborgs may be harbingers of a new world stranger than any we have yet experienced."

"[The decisionmaking role of the firm has progressed from the neoclassical standpoint of profit maximization to sales maximization, utility maximization, and satisficing. From the Operation Research point of view] ...the ideal picture is that someone, presumable the firm that hires the operations researcher, hands him, on a silver platter, an objective function. By talking to the engineers, or by looking into a few scientific laws, he determines the policy alternatives available and also the model"

"The development (rather than the history) of operations research as a science consists of the development of its methods, concepts, and techniques. Operations research is neither a method nor a technique; it is or is becoming a science and as such is defined by a combination of the phenomena it studies."

"We may recognize the subject of management cybernetics — which is seen as a rich provider of models for doing Operations research."

"The aim of management science is to display the best course of action in a given set of circumstances, and this must include all the circumstances."

"The 19th and first half of the 20th century conceived of the world as chaos. Chaos was the oft-quoted blind play of atoms, which, in mechanistic and positivistic philosophy, appeared to represent ultimate reality, with life as an accidental product of physical processes, and mind as an epi-phenomenon. It was chaos when, in the current theory of evolution, the living world appeared as a product of chance, the outcome of random mutations and survival in the mill of natural selection. In the same sense, human personality, in the theories of behaviorism as well as of psychoanalysis, was considered a chance product of nature and nurture, of a mixture of genes and an accidental sequence of events from early childhood to maturity. Now we are looking for another basic outlook on the world -- the world as organization. Such a conception -- if it can be substantiated -- would indeed change the basic categories upon which scientific thought rests, and profoundly influence practical attitudes. This trend is marked by the emergence of a bundle of new disciplines such as cybernetics, information theory, general system theory, theories of games, of decisions, of queuing and others; in practical applications, systems analysis, systems engineering, operations research, etc. They are different in basic assumptions, mathematical techniques and aims, and they are often unsatisfactory and sometimes contradictory. They agree, however, in being concerned, in one way or another, with "systems," "wholes" or "organizations"; and in their totality, they herald a new approach."

"Linear programming is viewed as a revolutionary development giving man the ability to state general objectives and to find, by means of the simplex method, optimal policy decisions for a broad class of practical decision problems of great complexity. In the real world, planning tends to be ad hoc because of the many special-interest groups with their multiple objectives."

"The concern of OR with finding an optimum decision, policy, or design is one of its essential characteristics. It does not seek merely to define a better solution to a problem than the one in use; it seeks the best solution... [It] can be characterized as the application of scientific methods, techniques, and tools to problems involving the operations of systems so as to provide those in control of the operations with optimum solutions to the problems."

"OR is the securing of improvement in social systems by means of scientific method"

"By the end of the war the new game theoretic methods that had been developed by von Neumann and Morgenstern were added to the toolkit and mathematical techniques that operations research scientists deployed. These proved very valuable, and game theoretic approaches took on great importance after the war."

"Operations research has many precursors and allied fields, including Taylorism (after Frederick W. Taylor), scientific management and management science, industrial engineering and systems analysis. As one early textbook explained, the roots of OR "are as old as science and the management function. Its name dates back only to 1940" (Churchman et al. 1957: 3). Certainly its practitioners have expended much energy and ink in search of an acceptable definition of OR. Morse tried unsuccessfully to halt the debate by declaring OR to be 'the activity carried on by members of the Operations Research Society' (Morse 1953: 159) But his colleagues were not so easily dissuaded from debate. Much of the concern with definition focused on the sometimes elusive distinctions between OR and neighbouring fields; the attempt to define, or redefine, OR was also born of the desire to allow the subject to evolve beyond the orthodoxy of wartime experience. Crucial considerations included the balance between model and application, and the complexity of the mathematics involved."

"It is hard to say whether increasing complexity is the cause or the effect of man's effort to cope with his expanding environment. In either case a central feature of the trend has been the development of large and very complex systems which tie together modern society. These systems include abstract or non-physical systems, such as government and the economic system. They also include large physical systems like pipe line and power distribution systems, transportation and electrical communication systems. The growth of these systems has increased the need not only for over-all planning, but also for long-range development of the systems. This need has induced increased interest in the methods by which efficient planning and design can be accomplished in complex situations where no one scientific discipline can account for all the factors. Two similar disciplines which emerged about the time of World War II to cope with these problems are called systems engineering and operations research."

"The Mathematical School ; Although mathematical methods can be used by any school of management theory, and have been, I have chosen to group under a school those theorists who see management as a system of mathematical models and processes. Perhaps the most widely known group I arbitrarily so lump are the operations researchers or operations analysts, who have sometimes anointed themselves with the rather pretentious name of "management scientists." The abiding belief of this group is that, if management, or organization, or planning, or decision making is a logical process, it can be expressed in terms of mathematical symbols and relationships. The central approach of this school is the model, for it is through these devices that the problem is expressed in its basic relationships and in terms of selected goals or objectives."

"We should no longer have trouble explaining the scope and methods of operations research to the layman. We already can say: operations research is the activity carried on by members of the Operational Research Society; its methods are those reported in our journal."

"The conclusions of most good operations research studies are obvious."

"It may be said that systems engineering is directed at the design and operating problems of production processes and units, while operations research is applied to problems in other areas of management such as sales, marketing, and external finance."

"Herbert A. Simon's scientific output goes far beyond the disciplines in which he has held professorships: political science, administration, psychology and information sciences. He has made contributions in the fields of science theory, applied mathematics, statistics, operations research, economics and business and public administration (and), in all areas in which he has conducted research, Simon has had something of importance to say.""

"The development of information research has increased considerably the interaction of emerging information science with other disciplines. Librarianship has traditionally had links with education and classification and has drawn ideas from logic and philosophy. But during the last fifty years new insights and methods have been derived from sociology and social psychology, from computer science, from operations research and related quantitative approaches, from communications research, from linguistics, and most recently from the new hybrids: cognitive science and artificial intelligence."

"Operations research is a scientific approach to problem-solving for executive management."

"Terrorist attacks can shake the foundations of our biggest buildings, but they cannot touch the foundation of America. These acts shattered steel, but they cannot dent the steel of American resolve."

"We shape our buildings, thereafter they shape us."

"I read somewhere that the tallest buildings in a town reflect that society’s values; if so, this one screamed that money mattered and beauty didn’t."

"Dancing and architecture are the two primary and essential arts. The art of dancing stands at the source of all the arts that express themselves first in the human person. The art of building, or architecture, is the beginning of all the arts that lie outside the person; and in the end they unite."

"I approach each building as a sculptural object, a spatial container, a space with light and air, a response to context and appropriateness of feeling and spirit. To this container, this sculpture, the user brings his baggage, his program, and interacts with it to accommodate his needs. If he can't do that, I've failed."

"Life is chaotic, dangerous, and surprising. Buildings should reflect that."

"Three things are to be looked to in a building: that it stand on the right spot; that it be securely founded; that it be successfully executed."

"I knew, as everyone knows, that the easiest way to attract a crowd is to let it be known that at a given time and a given place some one is going to attempt something that in the event of failure will mean sudden death. That's what attracts us to the man who paints the flagstaff on the tall building, or to the 'human fly' who scales the walls of the same building."

"There can be little doubt that in many ways the story of bridge building is the story of civilisation. By it we can readily measure an important part of a people’s progress."

"A building has integrity just like a man. And just as seldom."

"We require from buildings, as from men, two kinds of goodness: first, the doing their practical duty well: then that they be graceful and pleasing in doing it; which last is itself another form of duty."

"I do not believe that ever any building was truly great, unless it had mighty masses, vigorous and deep, of shadow mingled with its surface."

"Better the rudest work that tells a story or records a fact, than the richest without meaning. There should not be a single ornament put upon great civic buildings, without some intellectual intention."

"To be a man is to be responsible: to be ashamed of miseries you did not cause; to be proud of your comrades' victories; to be aware, when setting one stone, that you are building a world."

"INDUSTRIAL DESIGN is destined to become a universal language ; for in our material age of rapid transition, from abstract, to applied, Science — in the midst of our extraordinary tendency towards the perfection of the means of conversion, or manufacturing production — it must soon pass current in every land."

"In short, intelligence, considered in what seems to be its original feature, is the faculty of manufacturing artificial objects, especially tools to make tools, and of indefinitely urging the manufacture."

"Mechanical engineering may be defined as the manufacture, installation, and repair of all kinds of machinery (including machine tools), prime movers and boilers, and engines."

"A wide market awaited the manufacturer of food products who would set purity and quality above everything else in their preparation."

"The two main purposes of mechanical engineering are: first, to design and make tools and equipment for turning out machinery required by all branches of engineering, industry, and commerce, and, second, to design and manufacture, by means of said tools and equipment."

"There are many branches of manufacturing industry which greatly depend for their success upon the designer's art, and it is necessary that the industrial designer should possess a knowledge of the processes of the manufacture in which his designs will be utilized, as well as of the properties and capabilities of the material to which they will be applied."

"We went through one of the big automobile factories to-day.... The foundry interested me particularly. The heat was terrific. The men seemed weary. Here manual labour is a drudgery and toil is slavery. The men cannot possibly find any satisfaction in their work. They simply work to make a living. Their sweat and their dull pain are part of the price paid for the fine cars we all run. And most of us run the cars without knowing what price is being paid for them.... We are all responsible. We all want the things which the factory produces and none of us is sensitive enough to care how much in human values the efficiency of the modern factory costs."

"What gradually swung the balance of resources back in the Allies' favour were two factors: the sheer speed and scale of American rearmament, which dwarfed anything that the Germans and Japanese, or even the British, had thought possible: and the swift revival of the Soviet economy after the mauling it received in 1941, when it sustained losses so severe that most pundits assumed the worst. Without the extraordinary exodus of Soviet machinery and labour from the war zones of the western Soviet Union to the harsh plains of Siberia, Stalin's armies would have been like the Tsar's in 1916, the soldiers in the second rank picking up the guns and boots of their dead vanguard as they scurried into battle. Against every expectation Soviet society worked feverishly to turn out the tanks and aircraft their soldiers needed. With only a quarter of the steel available to Germany, Soviet industry turned out more tanks, gun and planes than her German enemy throughout the war."

"The great cry that rises from our manufacturing cities, louder than their furnace blast, is all in very deed for this, — that we manufacture everything there except men; we blanch cotton, and strengthen steel, and refine sugar, and shape pottery; but to brighten, to strengthen, to refine, or to form a single living spirit, never enters into our estimate of advantages."

"Mechanical engineering is applicable rather to works connected with private enterprise, such as the designing and construction of steam machinery for the purposes of navigation and transportation, the adaptation of such machinery to mills and factories, the construction of water-wheels, the fabrication of materials, iron, steel, and brass, for the purposes of the engineer, the architect, and manufacturer ; and the manufacture of implements and machinery for agriculture, for mining, and for domestic purposes."

"It would be foolish to describe the logistics hub as merely ugly, for it has the horrifying, soulless, immaculate beauty characteristic of many of the workplaces of the modern world."

"On my orders, coalition forces have begun striking selected targets of military importance to undermine Saddam Hussein's ability to wage war. These are opening stages of what will be a broad and concerted campaign. More than 35 countries are giving crucial support -- from the use of naval and air bases, to help with intelligence and logistics, to the deployment of combat units. Every nation in this coalition has chosen to bear the duty and share the honor of serving in our common defense."

"Hannibal excelled as a tactician. No battle in history is a finer sample of tactics than Cannae. But he was yet greater in logistics and strategy. No captain ever marched to and fro among so many armies of troops superior to his own numbers and material as fearlessly and skillfully as he. No man ever held his own so long or so ably against such odds. Constantly overmatched by better soldiers, led by generals always respectable, often of great ability, he yet defied all their efforts to drive him from Italy, for half a generation. … As a soldier, in the countenance he presented to the stoutest of foes and in the constancy he exhibited under the bitterest adversity, Hannibal stands alone and unequaled. As a man, no character in history exhibits a purer life or nobler patriotism."

"That total war would ultimately be decided by material rather than moral factors was not lost on the Germans. 'The first essential condition for an army to be able to stand the strain of battle', wrote Rommel, 'is an adequate stock of weapons, petrol and ammunition. In fact, the battle is fought and decided by the quartermasters before the shooting begins. The bravest men can do nothing without guns, the guns nothing without plenty of ammunition; and neither guns nor ammunition are of much use in mobile warfare unless there are vehicles with sufficient petrol to haul them around.' By the final year of the war, an active US army division was consuming around 650 tons of supplies a day. Because a single army truck could carry just five tons, this posed a formidable logistical challenge. Indeed, as supply lines were stretched from 200 to 400 miles in the months after D-Day, deliveries to the advancing armies slumped from 19,000 tons a day to 7,000 tons - hence the slackening of the pace of the Allied advance in the second half of 1944 and one defect of Montgomery's grab for Arnhem. The last phase of the war revealed the importance (consistently underrated by both the Germans and the Japanese) of assigning ample numbers of men to the task of supply rather than combat. The ratio of combatants to non-combatants in the German army was two to one; but the equivalent American ratio in the European theatre was one to two. In the Pacific, the Japanese ratio was one to one; the Americans had eighteen non-combatants for every man at the front. As the war came to an end, the United States had nearly as many men under arms as the Soviet Union (around twelve million in each case) but only a minority of Americans were actually engaged in combat."

"Logistics is the ball and chain of armored warfare."

"It struck me as I waited that all great enterprises are about logistics. Not genius or inspiration or flights of imagination, skill or cunning, but logistics. Building pyramids or landing spacecraft on Jupiter or invading whole continents or painting divine scenes over the roofs of chapels: logistics."

"Experience has shown that the mass-armies of “democratic” states fight with greater zeal when they are animated by hatred and supported by a hate-crazed populace that fancies it is fighting a holy war. Lies have therefore become military equipment, a kind of mental logistics; but it is the essence of such propaganda that its spuriousness is known only to the persons who manufacture it. The model of such operations is the famous lie-factory managed by Lord Bryce during the First World War, in which a corps of expert technicians forged photographs, while expert liars, including Arnold Toynbee, concocted stories, of “atrocities,” to inspire the emotionally overwrought British with a fanatical hatred of the incredibly bestial Germans and with a noble Christian ardor to kill them."

"Decision theory can be pursued not only for the purposes of building foundations for political economy, or of understanding and explaining phenomena that are in themselves intrinsically interesting, but also for the purpose of offering direct advice to business and governmental decision makers. For reasons not clear to me, this territory was very sparsely settled prior to World War II. Such inhabitants as it had were mainly industrial engineers, students of public administration, and specialists in business functions, none of whom especially identified themselves with the economic sciences. Prominent pioneers included the mathematician, Charles Babbage, inventor of the digital computer, the engineer, Frederick Taylor and the administrator, Henri Fayol. During World War II, this territory, almost abandoned, was rediscovered by scientists, mathematicians, and statisticians concerned with military management and logistics, and was renamed “operations research” or “operations analysis.” So remote were the operations researchers from the social science community that economists wishing to enter the territory had to establish their own colony, which they called “management science”."

"An army marches on its stomach."

"For myself I hold no preferences among flowers, so long as they are wild, free, spontaneous. Bricks to all greenhouses! Black thumb and cutworm to the potted plant!"

"When you can dump a load of bricks on a corner lot, and let me watch them arrange themselves into a house — when you can empty a handful of springs and wheels and screws on my desk, and let me see them gather themselves together into a watch — it will be easier for me to believe that all these thousands of worlds could have been created, balanced, and set to moving in their separate orbits, all without any directing intelligence at all."

"Prisons are built with stones of Law. Brothels with the bricks of religion."

"A career is like a house: it’s made of many bricks, and each brick has the same value, because without any one of them, the house would collapse."

"Composing is like driving down a foggy road toward a house. Slowly you see more details of the house-the color of the slates and bricks, the shape of the windows. The notes are the bricks and the mortar of the house."

"Most software today is very much like an Egyptian pyramid with millions of bricks piled on top of each other, with no structural integrity, but just done by brute force and thousands of slaves."

"The reason for this project comes from my childhood, that is clear to me. I did not have any toys. So, I played in the bricks of ruined buildings around me and with which I built houses."

"I don't think you can separate a place from its history. I think a place is much more than the bricks and mortar that go into its construction. I think it's more than the accidental topography of the ground it stands on."

"The philosopher believes that the value of his philosophy lies in the whole, in the building: posterity discovers it in the bricks with which he built and which are then often used again for better building: in the fact, that is to say, that building can be destroyed and nonetheless possess value as material."

"Science is built of facts the way a house is built of bricks: but an accumulation of facts is no more science than a pile of bricks is a house."

"No man ever wetted clay and then left it, as if there would be bricks by chance and fortune."

"If I could only remember that the days were, not bricks to be laid row on row, to be built into a solid house, where one might dwell in safety and peace, but only food for the fires of the heart."

"It is pretty generally admitted that few of them were to be trusted within reach of a trowel and a pile of bricks."

"Bricks... should not be made of sandy or pebbly clay, or of fine gravel, because when made of these kinds they are in the first place heavy; and secondly when washed by the rain as they stand in walls, they go to pieces and break up, and the straw in them does not hold together on account of the roughness of the material. They should rather be made of white and chalky or of red clay, or even of a coarse grained gravelly clay. These materials are smooth and therefore durable; they are not heavy to work with, and are readily laid."

"Bricks should be made in Spring or Autumn so that they may dry uniformly."

"Bricks will be most serviceable if made two years before using; for they cannot dry thoroughly in less time. When fresh undried bricks are used in a wall, the stucco covering stiffens and hardens into a permanent mass, but the bricks settle and... the motion caused by their shrinking prevents them from adhering to it, and they are separated from their union with it....at Utica in constructing walls they use brick only if it is dry and made five years previously, and approved as such by the authority of a magistrate."

"There are also half bricks....As the bricks are always laid so as to break joints, this lends strength and a not unattractive appearance to both sides of such walls."

"Taking courage and looking forward from the standpoint of higher ideas born of the multiplication of the arts, they gave up huts and began to build houses with foundations, having brick or stone walls, and roofs of timber and tiles; next, observation and application led them from fluctuating and indefinite conceptions to definite rules of symmetry. Perceiving that nature had been lavish in the bestowal of timber and bountiful in stores of building material, they... embellished them with luxuries."

"With the present importance of the city [of Rome.] and the unlimited numbers of its population, it is necessary to increase the number of dwelling-places indefinitely. Consequently, as the ground floors could not admit of so great a number living in the city, the nature of the case has made it necessary to find relief by making the buildings high. In these tall piles reared with piers of stone, walls of burnt brick, and partitions of rubble work, and provided with floor after floor, the upper stories can be partitioned off into rooms to very great advantage. The accommodations within the city walls being thus multiplied as a result of the many floors high in the air, the Roman people easily find excellent places in which to live."

"On the top of the wall lay a structure of burnt brick, about a foot and a half in height, under the tiles and projecting like a coping. ...when the tiles on the roof are broken or thrown down by the wind so that rain-water can leak through, this burnt brick coating will prevent the crude brick from being damaged, and the cornice-like projection will throw off the drops beyond the vertical face, and thus the walls, though of crude brick structure, will be preserved intact."

"With regard to burnt brick... If not made of good clay or if not baked sufficiently, it shows itself defective... when exposed to frosts and rime. Brick that will not stand exposure on roofs can never be strong enough to carry its load in a wall. Hence the strongest burnt brick walls are those which are constructed out of old roofing tiles."

"As for "wattle and daub" I could wish that it had never been invented. The more it saves in time and gains in space, the greater and the more general is the disaster that it may cause; for it is made to catch fire, like torches. It seems better, therefore, to spend on walls of burnt brick, and be at expense, than to save with "wattle and daub," and be in danger. And, in the stucco covering, too, it makes cracks from the inside by the arrangement of its studs and girts. For these swell with moisture as they are daubed, and then contract as they dry, and by their shrinking cause the solid stucco to split. But since some are obliged to use it either to save time or money, or for partitions on an unsupported span, the proper method of construction is as follows. Give it a high foundation so that it may nowhere come in contact with the broken stone-work composing the floor..."

"Physics deals with a great many quantities that have both size and direction, and it needs a special mathematical language —the language of vectors —to describe those quantities. This language is also used in engineering, the other sciences, and even in common speech."

"We have a lot of genome-editing tools – like zinc finger nucleases, or CRISPR/Cas9 systems – that could theoretically allow you to epigenetically seek out and turn on genes that make your muscles physically large, make you strategically minded, incredibly fast, or increase your stamina. Of course, at this point, these types of things have been explored mostly in lab mice, but it's fun to speculate."

"Changing animals by putting human genes or cells into their structure is one way of making them more resemble the bit of the human condition you're interested in studying."

"The entire “library” of genetic instructions that an organism inherits is called its genome. A typical human cell has two similar sets of chromosomes, and each set has approximately 3 billion nucleotide pairs of DNA. If the one-letter abbreviations for the nucleotides of a set were written in letters the size of those you are now reading, the genetic text would fill about 700 biology textbooks."

"Three important research developments have made the genomic and proteomic approaches possible. One is “high-throughput” technology, tools that can analyze many biological samples very rapidly. The second major development is bioinformatics, the use of computational tools to store, organize, and analyze the huge volume of data that results from high-throughput methods. The third development is the formation of interdisciplinary research teams—groups of diverse specialists that may include computer scientists, mathematicians, engineers, chemists, physicists, and, of course, biologists from a variety of fields."

"He was stiff and sometimes a little strange, which was what you’d expect from an engineer, but he had a moral backbone as inflexible as a fossilized dinosaur’s."

"Some aspects of engineering professionalism, such as (1) sensitivity to risk (2) awareness of the social context of technology, (3) respect for nature, and (4) commitment to the public good, cannot be adequately accounted for in terms of rules, certainly not negative rules. Virtue ethics is a more appropriate vehicle for expressing these aspects of engineering professionalism. Some of the unique features of virtue ethics are the greater place it gives for discretion and judgment and also for inner motivation and commitment."

"As a guide to engineering ethics, I should like to commend to you a liberal adaptation of the injunction contained in the oath of Hippocrates that the professional man do nothing that will harm his client. Since engineering is a profession which affects the material basis of everyone’s life, there is almost always an unconsulted third party involved in any contact between the engineer and those who employ him — and that is the country, the people as a whole. These, too, are the engineer’s clients, albeit involuntarily. Engineering ethics ought therefore to safeguard their interests most carefully. Knowing more about the public effects his work will have, the engineer ought to consider himself an “officer of the court” and keep the general interest always in mind."

"If we combine the benefits of a human physiology maintained at the level of effectiveness possessed by our bodies when we were children (e.g., dechronification), along with the ability to deal with almost any form of severe trauma (via nanosurgery), then there are very few diseases or conditions that cannot be cured using nanomedicine. The only major class of incurable illness which nanorobots can’t handle is the case of brain damage in which portions of your brain have been physically destroyed. This condition might not be reversible if unique information has been irrevocably lost (say, because you neglected to make a backup copy of this information). There are several other minor “incurable” conditions, but all of these similarly relate to the loss of unique information."

"Nanorobots constructed of diamondoid materials cannot be destroyed by our immune system. They can be made to be essentially impervious to chemical attack. However, the body may react to their presence in a way that may interfere with their function. This raises the issue of nanorobot biocompatibility."

"The key issue for enabling full-immersion reality is obtaining the necessary bandwidth inside the body, which should be available using the in vivo fiber network I first proposed in Nanomedicine, Vol. I (1999). Such a network can handle 1018 bits/sec of data traffic, capacious enough for real-time brain-state monitoring. The fiber network has a 30 cm3 volume and generates 4-6 watts waste heat, both small enough for safe installation in a 1400 cm3 25-watt human brain. Signals travel at most a few meters at nearly the speed of light, so transit time from signal origination at neuron sites inside the brain to the external computer system mediating the upload are ~0.00001 millisec which is considerably less than the minimum ~5 millisec neuron discharge cycle time. Neuron-monitoring chemical sensors located on average ~2 microns apart can capture relevant chemical events occurring within a ~5 millisec time window, since this is the approximate diffusion time for, say, a small neuropeptide across a 2-micron distance. Thus human brain state monitoring can probably be “instantaneous,” at least on the timescale of human neural response, in the sense of “nothing of significance was missed."

"It will probably not be possible to eradicate all infectious disease. The current bacterial population of Earth may be ~1031 organisms and so the chances are good that most of them are going to survive in some host reservoir, somewhere on the planet, for as long as life exists here, despite our best efforts to eradicate them. However, it should be possible to eliminate all harmful effects, and all harmful natural disease organisms, from the human body, allowing us to lead lives that are free of pathogen-mediated illness (at least most of the time). A simple antimicrobial nanorobot like the microbivore should be able to eliminate even the most severe bloodborne infections in treatment times on the order of an hour; more sophisticated devices could be used to tackle more difficult infection scenarios."

"Regarding microbial adaptability, it makes no difference if a bacterium has acquired multiple drug resistance to antibiotics or to any other traditional treatment – the microbivore will eat it anyway, achieving complete clearance of even the most severe septicemic infections in minutes to hours, as compared to weeks or even months for antibiotic-assisted natural phagocytic defenses, without increasing the risk of sepsis or septic shock. Hence microbivores, each 2-3 microns in size, appear to be up to ~1000 times faster-acting than either unaided natural or antibiotic-assisted biological phagocytic defenses, and can extend the doctor’s reach to the entire range of potential bacterial threats, including locally dense infections."

"Ames: The President's own vital signs -- heartbeat, brainwave pattern, blood pressure and so on -- are constantly monitored and relayed by his internal nanomachines. This information along with the DNA pattern serve as a biometric password, unbreakable even by the latest parallel processor supercomputers. The password entry itself cannot be performed unless brainwave patterns and heartbeats fall within normal parameters, rendering chemical and other forms of coercion impractical."

"Nastasha Romanenko: Solid Snake certainly managed to live up to his reputation. He adroitly wove his way through the enemy's patrols and infiltrated the nuclear weapons disposal plant, where he made contact with Donald Anderson, the DARPA (Defense Advanced Research Projects Agency) director. Throughout the mission, we had radio monitoring capability over Snake's every movement thanks to his internal nanomachines."

"Nastasha Romanenko: What awaited Snake after his brief encounter with Liquid was Ocelot's KGB-tested 'interrogation' techniques. Ocelot apparently had no interest in extracting information, but rather appeared to be enjoying the acts of torture for their own sake. Snake's ragged gasps echoed from the radio in the silence of the control room. The heart rate and other physiological data transmitted by his nanomachines graphically demonstrated the extent of his suffering."

"Modern industry is stated by some writers to have begun in 1738 when brought out a . Others place the period as between 1750 and 1800, when the and came into being. It was marked by the development of labor-saving machinery. It was brought about by the change from handicraft to manufacture."

"Early British economists held that the application of the principle of division of labor was the basis of manufacture.... Charles Babbage, believed ... in [an] "Economy of Machinery and Manufacture." It appears, however, that another principle is the basic one in the rise of industry. It is the transference of skill. The transference of skill from the inventor or designer to the power-driven mechanism brought about the industrial revolution from handicraft to manufacture. It will be necessary to refer to this principle frequently throughout this report, in showing the meaning and position of management in industry."

"Man is by nature a pragmatic materialist, a mechanic, a lover of gadgets and gadgetry; and these are the qualities that characterize the "establishment" which regulates modern society: pragmatism, materialism, mechanization, and gadgetry. Woman, on the other hand, is a practical idealist, a humanitarian with a strong sense of noblesse oblige, an altruist rather than a capitalist."

"The twentieth century is going much further towards the transference of skill from the worker to the machine."

"The Methods of Industrial Management. — A committee of the American Society of Mechanical Engineers made an extensive canvass in the fall of 1912 to determine what were the new elements in modern management as well as what the committee designated as the regulative principles of industrial management. The committee confirmed Adam Smith's statement made in 1776 in his "Wealth of Nations," in which he held that the application of the principle of division of labor was the basis of manufacture. The committee also agreed with Charles Babbage, who in his work entitled "Economy of Machinery and Manufacture" written in 1832, added another principle, namely the transference of skill."

"I believe that the horrifying deterioration in the ethical conduct of people today stems from the mechanization and dehumanization of our lives. A disastrous by-product of the development of the scientific and technical mentality. We are guilty. Man grows cold faster than the planet he inhabits."

"Everyone knows the difference between a fisherman, a sailor, a swimmer, a cyclist, and people who fish, sail, swim and cycle for sport. The last are technicians; as Jünger says, they “tend to carry to perfection the mechanical side of their activity.” This mechanization of actions is accompanied by the mechanization of sporting goods—stop watches, starting machines, and so on. In this exact measurement of time, in the precision training of muscular actions, and in the principle of the “record,” we find repeated in sport one of the essential elements of industrial life."

"In olden times when there was a war, it was a human-to-human confrontation. The victor in battle would directly see the blood and suffering of the defeated enemy. Nowadays, it is much more terrifying because a person in an office can push a button and kill millions of people and never see the human tragedy that he or she has created. The mechanization of war, the mechanization of human conflict, poses an increasing threat to peace."

"Developments towards mechanization originated from the periodical press and newspapers."

"It... has long been realized by those engaged in the work of installing scientific management, that transference of skill is one of the most important features... The importance of transference of skill was realized many years ago. Studies in division of work and in elapsed time of doing work were made by Adam Smith, Charles Babbage, M. Coulomb and others, but accurate measurement in management became possible when Mr. Taylor devised his method of observing and recording elementary unit net times for performance with measured allowance for fatigue."

"The strongest bulwark of authority is uniformity; the least divergence from it is the greatest crime. The wholesale mechanisation of modern life has increased uniformity a thousandfold. It is everywhere present, in habits, tastes, dress, thoughts and ideas. Its most concentrated dullness is "public opinion." Few have the courage to stand out against it. He who refuses to submit is at once labelled "queer," "different," and decried as a disturbing element in the comfortable stagnancy of modern life."

"Machine production, not only further division of labour in the production process, but it also transfers the skill of the worker to the operating machine. Mechanization intensifies this transference of skill from man to machine, making factory work simple."

"The overwhelming pressure of mechanization evident in the newspaper and the magazine, has led to the creation of vast monopolies of communication. Their entrenched positions involve a continuous, systematic, ruthless destruction of elements of permanence essential to cultural activity."

"One of the curious things about mathematics that clearly emerges... is that mathematics which is concerned with reasoning nevertheless creates processes which can be applied almost mechanically, that is, without reasoning. The thinking is, so to speak, mechanized and this mechanization enables us to solve complicated problems in no time. We think up processes so that we don't have to think."

"'How can you [accept] exploitation?' 'How can you like the complete mechanization of work?' 'How can you like bad art?' I have to answer that I accept it as being there, in the world."

"Besides black art, there is only automation and mechanization."

"Typography as the first mechanization of a handicraft is itself the perfect instance not of a new knowledge, but of applied knowledge."

"If the individual were no longer compelled to prove himself on the market, as a free economic subject, the disappearance of this kind of freedom would be one of the greatest achievements of civilization. The technological processes of mechanization and standardization might release individual energy into a yet uncharted realm of freedom beyond necessity. The very structure of human existence would be altered; the individual would be liberated from the work world's imposing upon him alien needs and alien possibilities. The individual would be free to exert autonomy over a life that would be his own."

"Advertising tends to make mechanized barbarians of us all."

"There is considerable danger that psychoanalysis, as well as other forms of psychotherapy and adjustment psychology, will become new representations of the fragmentation of man, that they will exemplify the loss of the individual's vitality and significance, rather than the reverse, that the new techniques will assist in standardizing and giving cultural sanction to man's alienation from himself rather than solving it, that they will become expressions of the new mechanization of man."

"The Mechanisation of Industry."

"Philosophy must re-emphasize man versus the collective body (with its envisaged collectivized mind), freedom versus the mechanization of inner and social life, common sense versus faith in science."

"Mechanization and regimentation are not new phenomena in history: what is new is the fact that these functions have been projected and embodied in organized form which dominate every aspect of our existence."

"The incentive to mechanization lay in the greater profits that could be extracted through the multiplied and efficiency of the machine."

"The mechanization of human labor was, in effect, the first step toward the humanization of the machine humanization in the sense of giving the automaton some of the mechanical equivalents of life-likeness."

"The characteristic feature of our modern mechanical improvements, is the introduction of self-acting tool machinery. What every mechanical workman has now to do, and what every boy can do, is not to work himself, but to superintend the beautiful labor of the machine. The whole class of workmen that depend exclusively on their skill is now done away with."

"Mechanisation leads to the decay of taste, the decay of taste leads to demand for machine-made articles and hence to more mechanisation, and so a vicious circle is established."

"Transference of skill, when considered with reference to the industrial revolution and the introduction of machinery, might easily be interpreted to mean the transference of skill from the workman to the machine. What actually happened was that the machine brought to the aid of the workmen some of the vast forces of nature; and in addition it superseded the skill of the hand worker. That this was a distinct loss to the hand worker who was unable to adjust himself to the new conditions is incontestable in the face of economic history; and the sad record of the change is a solenm warning to present day managers to take every step possible to make the adjustment to new methods of management as easy and gradual as possible. The machine developed a new kind of skill on the part of the operator; but now it is a minute skill easily acquired and subject to sudden loss with the change in the design of the machine."

"We conceive the prominent element in present-day industrial management to be: the mental attitude that consciously applies the transference of skill to all the activities of industry. Here emphasis is placed upon the word all, for the restricted application of this principle to machines and tools has been highly developed for a long period. But its conscious application in a broad way to the production departments, and particularly to the workmen, we believe has been made during the last quarter of a century."

"Coal being then the chief source of power, much industrial reconstruction depended on there being a plentiful and cheap supply. But the newly nationalized industry was not doing well. Productivity failed to increase in step with increases in mechanization. Men were leaving the mines in large numbers for more attractive opportunities in the factories. Among those who remained, absenteeism averaged 20 percent. Labor disputes were frequent despite improved conditions of employment. Some time earlier the National Coal Board had asked the Institute to make a comparative study of a high producing, high morale mine and a low producing, low morale, but otherwise equivalent mine."

"Paul wondered at what thorough believers in mechanization most Americans were, even when their lives had been badly damaged by mechanization."

"Every machine is constructed for the purpose of performing certain mechanical operations, each of which supposes the existence of two other things besides the machine in question, namely, a moving power, and an object subject to the operation, which may be termed the work to be done. Machines, in fact, are interposed between the power and the work, for the purpose of adapting the one to the other."

"Mediocrity serves it best because mechanization best serves the mediocre."

"It always demands a far greater degree of courage for an individual to oppose an organized movement than to let himself be carried along with the stream — individual courage, that is, a variety of courage that is dying out in these times of progressive organization and mechanization."

"Gaudí was drawn not just to the aesthetics of the catenary but also to what it represented mathematically. His use of catenaries made the structural mechanics of a building a principal feature of its design. Gaudí realized that the entire architecture of a building could be drafted using a model of hanging chains... when he was commissioned to design a church the Colònia Güell... he made an upside-down skeleton of the project. Instead of using metal chains, he used string weighed down by hundreds of sachets containing lead shot. The weight of each sachet on the string created a mesh of 'transformed' catenary curves. The arches of these transformed catenaries were the most stable curves to withstand a corresponding weight at the same position (such as the roof, or building materials)."

"In 1690... Jacob Bernoulli brought up the problem of the catenary in a memoir... in the '...Huygens' solution represents the past... a complex, though skillful, geometrical method. Leibniz, using his new [infinitesimal calculus] reaches a correct analytical formula...y/a = (b^\frac{x}{a} + b^\frac{-x}{a})/2 where a is [a] segment... and b... corresponds to... e... ...supplied two correct constructions ...presents valid statistical arguments and... new and important... equations of equilibrium in differential form. ...In 1697-1698, Jacob Bernoulli was the first to derive the general equations that not only solved the problem, but also permitted the treatment of the more general theme of the equilibrium of a flexible rope, subject to any distribution of tangential (f_t) and normal (f_n) forces. Bernoulli's equations are...\frac{dT}{ds} + f_t = 0, \qquad \frac{T}{r} + f_n= 0where T is the tension, s the curvilinear abscissa, and r the radius of curvature."

"The largest catenary structure of masonry is the Great Hall of the Palace of Taq Kisra, at Qesiphon, then the capital of Persia."

"The trolley-wire must... be suspended with only a very small sag, and to obtain this result without excessive tension in the wire the span must be relatively short, i.e. of the order of 10 ft. to 15 ft. It is obvious that for these short spans the method of construction adopted in tramway practice would be unsuitable, both from the mechanical as well as the electrical standpoint. However, by adopting the catenary system—that is, supporting the trolley-wire from another wire, suspended with considerable sag between supports of moderate span—we are able to obtain a level trolley-wire with a relatively small number of supporting structures. The wire from which the trolley-wire is supported is called the "catenary" or "messenger" wire, and by insulating this wire from the supporting structures there is no necessity for insulated hangers on the trolley-wire."

"Within a shed erected on the construction site of the church of the Sagrada family... Gaudí... made an upside-down model using lightweight cables to represent the structural lines of the future church—a model based on the structural notion of the inverted catenary. ...Analogically represented by little pouches filled with lead pellets the action of the stresses has been done ...The resulting chain configurations are used to determine the geometrical shapes and structural profiles of columns, pillars, arches, and vaults. ...Vicens Vilarrubias i Valls took photos of the model ...Gaudí used these photos upside-down to draw over them the external and internal elevations, studies of details and sections of the building."

"Corol. 6.—In a vertical plane, but in an inverted situation, the chain will preserve its figure without falling, and therefore will constitute a very thin arch or fornix: that is, infinitely small, rigid, polished spheres, disposed in an inverted curve of a catenaria, will form an arch no part of which will be thrust outwards or inwards by other parts, but, the lowest parts remaining firm, it will support itself by means of its figure... none but the catenaria is the figure of the true and legitimate arch or fornix. And when the arches of other figures is supported, it is because in their thickness some catenaria is included. ...From Corol. 5... it may be collected, by what force an arch or buttress presses a wall outwardly, to which it is applied. For this is the same with that part of the force sustaining the chain, which draws according to a horizontal direction. For the force which in the chain draws inwards, in an arch equal to the chain drives outwards. All other circumstances, concerning the strength of walls to which arches are applied, may be geometrically determined from this theory, which are the chief things in the construction of edifices."

"What has been objected by an anonymous author, in the Leipsic Acts of Feb. 1699, in his animadversions on my demonstrations concerning the catenary, is this: that I have undertaken to demonstrate, after my manner, a matter found out and published by others seven years ago. This is true, and I cannot find any thing in it that is blame worthy. Those great men Huygens, Leibnitz, and Bernouilli, have discovered and communicated many properties of the catenaria, but without demonstration. I have contrived demonstrations, which was the thing I undertook to do. But was this matter that is the nature and primary properties of the catenaria all found out and published by others? ...From all ages architects have made use of arches in public buildings, as well for strength as beauty. Yet what was the true geometrical figure of an arch was not known before my demonstrations came out."

"It was comparatively late that the theory of arches attracted the notice of mathematicians. Dr. Hooke gave the hint, that the figure of a perfectly flexible cord or chain, suspended from two points, was the proper form for an arch. Galileo considered the catenary as a parabolic curve, and John Bernouilli appears to have been the first who discovered its nature. Dr. Gregory (Phil. Trans. 1697) published an investigation of its properties, and observes that the inverted catenary is the best form for an arch on account of its lightness. This is true so long as it is not pressed by an extraneous weight. It is not, however, capable of bearing a load on any part, much less of being filled up on the spandrels, which must be the case in practice. Other considerations must be involved before it can be fitted to receive a roadway or other weight, either upon its crown or haunches."

"The flexible chain, hanging under the action of applied force, will assume a certain shape, namely the catenary if the chain is subjected only to its own weight, or a if the load is uniformly distributed horizontally. Whatever the load, there will be a corresponding shape, and the structural action in all cases is the same; purely tensile forces are transmitted along the centre line of the chain."

"As Hooke saw in 1675 with his ut pendet continuum flexile, sic stabit contiguum rigidum inversum, ...a hanging chain may be inverted to give a satisfactory arch to carry the same loads, but working in compression rather than tension. The compressive arch, however, if of vanishingly small thickness, would be in unstable equilibrium, and stability is conferred in practice by making the arch ring of finite depth. Now if purely compressive forces, without bending, are to be transmitted from one portion of the arch to the next (as purely tensile forces are transmitted in the chain), then the arch centre line can accept only a single type of loading. Thus a parabolic arch can carry only a uniformly distributed horizontal load (although the magnitude of the load is arbitrary). It is the depth in a real arch which enables the arch to carry wider ranges of loading; a large number of different idealized centre-line arches can be contained within a given practical profile. ...[T]his must be so, or no mediaeval bridge would have survived its decentering."

"The true Mathematical and Mechanical Form of all manner of Arches for building with the true butment necessary to each of them, a Problem which no Architectonick Writer hath ever yet attempted, much less perform'd. ...Ut pendet continaum flexile, sic stabit contiguum rigidum, which is the Linea Catenaria."

"I will begin with the subject of your bridge... and it is with great pleasure that I learn... that the execution of the arch of experiment exceeds your expectations. ...You hesitate between the catenary and portion of a circle. I have lately received from Italy a treatise on the equilibrium of arches, by the Abbé Mascheroni. It appears to be a very scientifical work. I have not yet had time to engage in it; but I find that the conclusions of his demonstrations are, that every part of the catenary is in perfect equilibrium. ...I would propose that you make your middle rail an exact catenary, and the interior and exterior rails parallels to that. It is true, they will not be exact catenaries, but they will depart very little from it; much less than portions of circles will."

"The Catenary has its name from Catena, a chain; being the curve which a regular and very flexible chain will assume, if suspended loosely from both ends. It seems to have been first noticed by the famous Galileo, who proposed it as the figure of an arch of equilibration, but unfortunately mistook it for a . In fact, the Catenary, near its vertex, differs insensibly from that curve, but afterwards deviates more considerably. ...the Parabola diverges faster from its axis than the Catenary. The error of Galileo in confounding those two curves was not perceived till , in 1669, ascertained, by actual experiment, that the Catenary is neither a Parabola nor an . It was in 1691, that the penetrating genius of James Bernoulli discovered the true nature of the catenarian curve. A similar investigation was soon produced by John Bernoulli, by Huygens, and by Leibnitz. This latter philosopher, whose powers of invention and stores of learning were alike transcendant, discovered the fine relation of the Catenary to the Logarithmic Curve."

"The most difficult properties of the Catenary were revealed before the close of the seventeenth century. This curve is entitled to particular attention, not only because it throws light on the theory of arches, but because it applies directly to the construction of suspended bridges, which are now deservedly coming into repute."

"A non-catenary curve might be perfectly doable, but it takes more material, it has bigger beam sections, and overall it is much more complicated to construct... Even if the cladding falls out, the interiors and everything else falls away and the whole thing turns to dust and rubble and sand, [the catenary] should still stand."

"I love the catenary because it tells the story of holding up the roof."

"The arch is one of those brilliant innovations... Spanning... with horizontal beams is a losing game. ...By converting all the stress that fractures the middle of... stone beams—technically tension—into compression on stone piers larger... spaces could be spanned. ...But shift the pressure even slightly off center, and the pillar is likely to collapse. ...In their early incarnations, the limitations of both arch and dome was the ability of craftsmen to shape the stones carefully enough to create blocks precisely in the wedge shapes needed for a particular arch. Despite their mathematical sophistication in most other respects, the architects of antiquity lacked a proper geometric solution to the ideal form of the arch. (It was not until 1675 that the English polymath Robert Hooke described mathematically the shape of an arch loaded in pure compression, that is, with no tension, by showing how it describes an upside-down version of the catenary curve of a hanging chain.) As a result, the only way they could design an arch, and its component stones, was completely by eye, and... such tolerances commanded high prices. Rome overcame this drawback with typical ingenuity, first replacing stones and mortar... and expensive stonecutters with relatively cheap bricklayers. Even more ingeniously, some anonymous Roman builder found how to combine the mortar—in Latin pulvis puteoli—with lime, sand, and gravel to make the first concrete. ...The concrete domes of Rome were not surpassed until the age of steel."

"Certainly the most striking contemporary example of a similar form [ arch] is to be found in St. Louis' ... In its incredible scale and construction out of metal plates this structure also serves as a convenient reminder of the important developments of the production of iron and steel that took place during the Industrial Revolution and that have so significantly affected arches as well as all other types of structural forms for the past 150 years."

"Concrete being such a fluid and dynamic material... finds its identity once it is contained. ...A few... who used the forming materials at hand [were]... Antoni Gaudi... ... ... Felix Candela... ... ... Miguel Fisac... Many of these early innovators pushed the computational envelope... Some, like Antoni Gaudi, looked to nature for inspiration. The question... Do we need to "reinvent forming" or just draw from nature, i.e., gravity—catenary action? as Gaudi did. Alan Chandler in fabric framework notes "...for Felix Candela and Christopher Alexander fabric acted as a permanent shutter (framework)..." Chandler speaks of the family of fabric construction that includes... s... Pneumatic structures... Hydrostatic structures and... Shell structures derived from membrane form-finding. When faced with extremely complicated and complex shapes Heinz Isler and Antoni Gaudi used fabric as a modeling tool. These visionaries recognized that hanging chains and fabrics, forming catenaries, are in pure tension and when inverted are in pure compression and very stable. Gaudi, whose ing preceded the works of Candela... looked to nature and natural forms—an approach today called biomimicry..."

"One can roll noncircular wheels over appropriate road surfaces. The most striking example of this is the fact that a can roll on a road that consists of linked catenaries (the catenaries are defined by y = - cosh x) ...(the ride is not smooth in the sense that the center does not move forward at a constant rate of rotation, but... the actual ride... feels quite smooth). This animation was inspired by an exhibit at San Francisco's ..."

"The story of aerodynamics is itself dynamic, replete with smashing successes, abject failures, and intense human competitions that have had major social, economic, and political consequences. It is a story of human beings, some exceptional and some average, some admirable and some not so. Above all, it is the story of an intellectual quest to understand those laws of nature that have allowed the continuing development of aircraft that can fly faster, higher, and more efficiently than their predecessors."

"Thin shells — Three-dimensional spatial structures made up of one or more curved slabs or folded plates whose thicknesses are small compared to their other dimensions. Thin shells are characterized by their three-dimensional load-carrying behavior, which is determined by the geometry of their forms, by the manner in which they are supported, and by the nature of the applied load."

"[T]he early work of Lambot... was one of the first applications of , but [was] also... a form of . His patent on wire-reinforced boats that was issued in 1847... This was the birth of reinforced concrete, but subsequent development differed from Lambot’s concept. The technology of the period could not accommodate the time and effort needed to make mesh of thousands of wires. Instead, large rods were used to make what is now called conventional reinforced concrete, and the concept of ferrocement was almost forgotten for 100 years."

"In the twentieth century, lightly reinforced brick shells were inspired by timbrel vaulting, a common building method in the Mediterranean. ... upon emigrating to the United States from in 1881, introduced the method with great success. His son, Rafael Guastavino, Jr. ...appears to be the first to have introduced steel reinforcing to thin brick shells. ...[T]wo patents... [1910, 1913] documented this system, which is a precursor to the thin shells of reinforced concrete developed widely in the ensuing decades."

"has designed some of the most striking thin shells in reinforced concrete of the second half of the twentieth century. He creates thin shells by hanging small membranes in tension and creating smooth curving surfaces that are then inverted and scaled up to create large-scale structures in compression. ...Within the constraint of economy, he discovered new forms from purely structural considerations and demonstrated the unlimited possibilities for thin compression shells to be found in hanging models."

"Candela did not invent the concrete shell; nor is he the first to make use of the hyperbolic paraboloid... Other people... have contributed more to the theoretical analysis of shell structures. But nobody else can claim credit for such an exciting variety of shell structures... [H]e has concentrated his effort in one particular sphere: the construction of light concrete roofs."

"Candela] is not just an engineer, or an architect, or a contractor and constructor, but all three... [W]hen he thinks out a new scheme, the method of construction and its economy is constantly in his mind. ...He prefers to obtain his economy by using his inventive skills as an engineer to reduce... material... [H]e recognizes the value of ... but he is also very conscious of its limitations. Especially is he skeptical about the value of the theory of elasticity as applied to concrete... of... calculations suggesting an accuracy which is purely fictitious... Designing... proceeds from a structural feeling acquired by experience and guided by rough calculations, a refinement of design... further analysis... and so on. ...[A] flair for making the right guess yields quicker and better results than a lot of mathematics... this is no reason for despising theoretical analysis... But one cannot design by theory..."

"[M]ost of Candela's structures are almost complete in themselves... the forms and proportions bear witness to his artistic sensibility. ...[B]alanced perfection ...makes a... structure into a work of art. ...[T]he whole must take precedence over any of its parts."

"The method of geometric modeling of multi-shell roofs depends mostly on the surface's properties forming the shell; their curvature, as well as continuity between them. ...s play a specific role, due to their characteristics. Catalan surfaces are s... They are oblique ruled surfaces which can be divided into two groups... second order—hyperbolic paraboloid... [and] of more than second order—s, cylindroids... The difference between hyperbolic paraboloid, conoid, and cylindroid results from different path of movement of a surface's ruling during formation. In all cases of Catalan surfaces' creation... each ruling is parallel to the fixed plane (not containing the surface's directrices)."

"... all through school had a reputation of working alone and of doing his work in an unusual way. ...in 1950 he graduated with a degree in civil engineering. For his final-year design project, he chose to study thin shells... Following graduation... he helped [Pierre] Lardy with teaching, and also worked on the many cases of structural failure [both at his alma mater, the Federal Technical Institute]... When Isler left his position... he considered... [a] career as a painter, but challenged by shell design problems... while doing free-lance engineering work.. in late 1954, he designed a pneumatic form, thin shell factory for the Trösch Company. It was the first work in which he set the form completely on his own. In 1955, at an international congress in Amsterdam, he presented publicly for the first time his new designs..."

"Torroja was a specialist in stress analysis... and he wrote a... book on the mathematical theory of elasticity. This... led him to see a connection at Algeciras between the stresses in the shell and the reinforcement... but not to express those stresses in... visually evident ribs. We contrast... Nervi's Little Sports Palace... whereas Nervi sees shells as ribbed, Torroja sees them as ribless... since domes tend to spread, Nervi designed ribbed buttresses... whereas Torroja avoids buttresses by connecting vertical supporting columns with a... polygonal ring of horizontal ties... prestressed to counteract dead load and to lift the shell slightly off its scaffold... probably the first application of prestressing to a doubly curved shell. In the Nervi dome... the buttresses are supported below ground on a ring which carries the horizontal thrust and... transmits the vertical weight to the ground. ...[These] choices related to the [respective] local traditions in Italy and Spain."

"The idea of form over mass also developed in Europe in the pioneering work of Dyckerhoff and Widmann... in Weisbaden, Germany. Working in reinforced concrete, the firm experimented with new ways to cover large spaces in the 1920s. The firm built domes and cylindrical "barrel" shells to serve as large roofs of extraordinary thinness. The possibilities... fascinated an Austrian civil engineering student, Anton Tedesko... who joined the firm in 1930."

"The Hershey Arena... Tedesko designed a thin reinforced concrete, barrel-shell roof, three and one-half inches thick, supported across its width by eight arches. ...A roof posed a different problem than a bridge or dam. On a bridge, live load from traffic is significant, and a dam must resist the live load of water on its upstream face. On a long-span concrete roof, live load (mainly rain and snow) is a small fraction of the dead load of the structure itself. Tedesko realized that the supporting arches did not need to be of uniform depth. ...[he] designed the arches to be able to... support the entire roof load, including the thin shell and all of the live load. He also made calculations to show that the thin shell could carry its own weight and the live load without help from the arches, except near their lowest edges. It was thus a conservative design..."

"Shells were not being done in the United States at all, and I started seeing pictures of these buildings coming out of South America... Italy and Spain... they happened to be all Latin countries. ...I thought, "God, how do I do this?" you know, these three-dimensional curved structures... [T]he greatest of them all... was Nervi... I found out that I couldn't find out how to design... them. ...I realized after many years of striving that a lot of them really didn't know how to design them. They were just doing it intuitively, and that was not satisfactory to an engineer. I needed to know a rational way of doing it, and that sent me back to school and... to studying... [I]t took me years and years of very hard intellectual work to find ways to do this. ...[W]hen I finally did it, I was one of the few guys in the country that had really made that much effort, and so I became a pioneer..."

"In 1958, Felix Candela completed his most significant work, the Los Manantiales Restaurant shell, in Xochimilco, Mexico City. ...[He] was taking a risk... The form was original, unexplored, and impossible to analyze precisely. Candela’s career, however, habitually flew in the face of precise analysis. In his first acclaimed shell, the Cosmic Ray Pavilion of the University of Mexico City, he also designed an unprecedented form, using almost no calculation... Candela’s subsequent designs relied increasingly on structural understanding and practical experience. As a designer-contractor, he had the unique responsibility of building his own solutions. By closely observing his buildings, and using smaller projects to test new ideas, he developed an acute sense of concrete shell behavior."

"The essential ingredients of a shell structure... are continuity and curvature. ...[S]hells are structurally continuous in the sense that they can transmit forces in a number of different directions in the surface of the shell... These have a quite different mode of action from skeletal structures... only capable of transmitting forces along discrete structural members. ...There seems to be a principle that closed surfaces are rigid. This principle is used in many areas of engineering construction. ...[A]lthough the ideas of 'closed' and 'open' shells... are fairly clear, it is difficult to quanitify intermediate cases into which... the majority of actual shell structures fall. ...There is a theorem, due to Cauchy, which states that a convex polyhedron is rigid. ...[N]on-convexity may produce deformability. ...While rigidity and strength are in many cases desirable attributes of shell structures, there are some important difficulties which can occur... [involving] unavoidable rigidity. ...[A] second broad principle... may be stated thus: efficient structures may fail catastrophically. Here I use the term 'efficient' to describe the consequences of employing the first principle. By designing a structure as... closed... we may be able to use thinner sheet material, and hence produce an economical, or efficient, design."

"For around 2000 years single and double curved shells structures, such as barrel and vault s, have been used to cover large spans in buildings. Until the twentieth century these were generally constructed either from masonry or some form of unreinforced concrete, materials strong in compression but relatively weak in tension. Well known examples such as the Pantheon... ... Santa Maria del Fiore... and St. Peter's Basilica... have a span to thickness ratio of less than 50 to 1, which is relatively thicker than a... typical hen's egg. ...[T]he stone vaulting of... medieval Gothic cathedrals... demonstrate the mason's art in the construction of... complex masonry shells. With the advent of reinforced concrete... strong in both compression and tension, it became possible... to construct thin shells with much higher span to thickness ratios... commonly... in the region of 500 to 1."

"At the time of construction of the Wyss shell, three-dimensional computer software was not available and it would have been extremely difficult to convey, using only normal engineering drawings, the required form of the concrete at the feet of the shell... To overcome the problems... proposed that, rather than making sketches, drawings, or even a model of the detail, they should resort to modelling it at full-scale on site."

"At the beginning, the was not covered by any type of roof. During the reconstruction... in 1964... the roof covering... was created. ...reinforced by cotton threads and covered by rubber layers. The material underwent large rheological displacements. In... 1968... catastrophe occurred, caused by wind and high humidity. In the eighties... a polyester fabric, intended only [for] seasonal application, was used. ...age and... repeated disassembling of the membrane caused its gradual destruction. ...In 2007 ...complete rebuilding ...assumed the roof to be a permanent structure. ...[V]erification of ...internal forces was conducted in 2012 ...by team."

"The resistant virtues of the structure that we make depend on their form; it is through their form that they are stable and not because of an awkward accumulation of materials. There is nothing more noble and elegant from an intellectual viewpoint than this; resistance through form."

"The emergence of lightweight structures can be traced back to the second half of the nineteenth Century. This period witnessed the advent of new material technologies such as steel, , resistant glass and, later, fabric membrane. Together with advances in analysis and design tools, engineers and architects have been challenged to build increasingly lighter structures. ...[A] pioneering structure was the lattice tower by... in 1896. In the 1920s, Anton Tedesko first introduced reinforced concrete thin shells in the United States. This expansion was pursued... by , and André Paduart... The limit of lightness was achieved with tensile structures constructed of prestressed cable nets and fabric membranes; the strength coming from the anticlastic curvature of the geometric surface. ...Nowadays, lightweight structures should be designed... by including the multitude of design contraints. This will result in hybrid systems lying at the boundary of different typologies."

"Nature does not apply the construction principle of a beam supported by two s. Forms developed by nature are following the rational attempt to achieve distinct functionalities with the smallest possible material - and energy consumption. An impressive example is the phenomena of egg shells... The shell principle is adopted by humans... in building construction, in order to achieve wide spanning and material saving 'slender' structures."

"The design of shells... implicates the design of internal stress fields of form dependent shapes... meeting the compatabilites of all boundary conditions..."

"The title of first pioneer of the HP hyperbolic paraboloid or hypar construction] in concrete in the 1930s belongs to Fernand Aimond for the projects that he constructed.., for the formulation of the theoretical structural membrane model, and for his influence both on [Giorgio] Baroni in Italy in the late 1930s and on Candela in Mexico in the 1950s."

"[[w:Membrane theory of shells|[M]embrane theory]]... is the theory of shells whose bending rigidity may be neglected. The spectacular simplification... makes it possible to examine a wide variety of shapes and support conditions. In particular, the stress problems of tanks and shell roofs... There is, of course a heavy penalty... [T]he inadequacies... can be discovered by a critical inspection of the... solutions, without any need for... solving the bending problem—a task which is often out of the reach of the practical engineer and even of the research worker. On the other hand, membrane theory is more than a first approximation... If a shell is so shaped and so supported that it can carry its load with a membrane stress system, it will be thin, light, and stiff and, therefore, the most desirable solution to a design problem. Membrane theory will guide the shell designer toward such structure."

"Shell-like structures are familiar enough in nature but the use of such structures as containers, aircraft fuselages, submarine hulls and roofing structures is only of recent origin. That the inherent strength of shells... has not been utilised much in the past is probably due to the difficulty in obtaining suitable material... [S]hell structures in general are these days constructed of such varied materials as steel, light alloy, plastics, wood and reinforced concrete. ...[T]o simplify analysis it will be assumed that the material... is homogeneous, isotropic and perfectly elastic. ...[A]lthough reinforced concrete behaves in a reasonably elastic manner only in the lower stress ranges the majority of reinforced concrete shell roofs that are constructed in practice are designed as elastic structures."

"The true Mathematical and Mechanical Form of all manner of es for building with the true butment necessary to each of them, a Problem which no Architectonick Writer hath ever yet attempted, much less perform'd. ...Ut pendet continaum flexile, sic stabit contiguum rigidum, which is the Linea Catenaria."

"The meandor compression spring... or corrugated spring... is a promising design variant for compression axle springs of composite material... The middle surface of the meander spring is the... "." ...[T]he middle surface ...is the ...[i.e.,] can be unrolled onto a flat plane without stretching or tearing it. ...[A] developable surface ...in three-dimensional space and ...complete ...is necessarily ruled. This property is of primary importance for manufacturability... The meander spring... is modeled for mechanical analysis as a thin shell."

"My invention shows a new product which helps to replace timber where it is endangered by wetness, as in wood flooring, water containers, plant pots, etc. The new substance consists of a metal net of wire or sticks which are connected or formed like a flexible woven mat. I give this net a form which looks in the best possible way, similar to the articles I want to create. Then I put in hydraulic cement or similar bitumen tar or mix, to fill up the joints."

"Cement Hall, Swiss National Exhibition, Zurich (1939)... was built by architect and engineer Hans Leuzinger and ... to demonstrate the potential of thin shells. ...The width of this parabolic shell is 50.32 ft... built by the Gunite method, [it] is only 2.36 in thick. ...A sculptural piece by Robert Maillart entititled "Endless Ribbon" [1935-1936]... is a thin shell built of reinforced concrete. This... can be classified within Constructivism or... constructive spatial art. [I]t represents... the direct correlation between the language of sculpture and that of modern thin-shell architecture that moves the sensitive engineer such as Maillart to express himself also as a sculptor. Maillart's structural shells as a whole testify to this similarity of language... He was the father of flared columns connecting with floor slabs to eliminate supporting beams and designed unique bridge forms. Maillart's name remains associated with innovative concrete forms that extend to the structural virtuosity of thin shells."

"Like Candela, Isler has concentrated his practice on thin s... Isler derives his forms not from analytical geometry (as were Candela's hypars) but directly from physical and funicular models - flexible membranes that assume the least energy, or minimal surface, for a specific boundary and force patterns. In the mid-1950s Isler invented two new form-making techniques, the first by using pneumatic models and the second by experimenting with hanging cloth models sprayed with water and put out to freeze in wintertime. Later, in 1965, he added a third technique that made shapes "by the flow method, by... the advancing velocity of a liquid inside a tube... At the wall, velocity is zero because of friction, whereas in the center there is maximum velocity... and forms a dome shape." While the frozen cloths conform to the funicular shape given by gravity, the other methods, pneumatic and flow, are hydraulic."

"There is... [a] need to code cheaper and accessible programs in line with using sustainable methods to better the livelihood of mankind. To address this issue a theory is formulated based on the Euler-Bernoulli beam model. This model is applicable to thin elements which include plate and membrane elements. This paper illustrates a finite element theory to calculate the master stiffness of a curved plate. The master takes into account the stiffness, the geometry and the loading of the element. The of this is established from which the load which is unknown in the matrix is evaluated by the principle of bifurcation."

"It was the great nineteenth century mathematician, Carl Gauss who proved mathematically that any curved surface, natural or man-made, can be characterized as only one of three different possible shapes: as -like, -like, or saddle-like. All three of these geometric shaped can be used as the basis for thin-shell structures."

"[T]he basic assumption in the linear theory of shells that the displacements of the shell are considered to be small in comparison to the thickness is abandoned in the present nonlinear analysis of shells. A shell is called thin if the maximum value of the ratio h/R, where h is the thickness of the shell and R is the principal radius of curvature of the middle surface... is less than or equal to 1/20 ...beyond this range... the shell is regarded as thick. ...in a large number of practical applications the ratio... lies in the range between 1/50 and 1/1000, making the theory of thin shells of great practical importance. In this chapter the nonlinear equations... in terms of orthoganal are derived assuming the material... is isotropic, homogeneous, and elastic. An important simplification based on the assumption that second invariant of the median surface strains in the expression for the extensional ... can be neglected, originally made by [Noah] Burger, is introduced to derive a simplified set of nonlinear... differential equations."

"Concrete being such a fluid and dynamic material... finds its identity once it is contained. ...A few... who used the forming materials at hand [were]... Antoni Gaudi... ... ... Felix Candela... ... ... Miguel Fisac... Many of these early innovators pushed the computational envelope... Some, like Antoni Gaudi, looked to nature for inspiration. The question... Do we need to "reinvent forming" or just draw from nature, i.e., gravity—catenary action? as Gaudi did. Alan Chandler in fabric framework notes "...for Felix Candela and Christopher Alexander fabric acted as a permanent shutter (framework)..." Chandler speaks of the family of fabric construction that includes... s... Pneumatic structures... Hydrostatic structures and... Shell structures derived from membrane form-finding. When faced with extremely complicated and complex shapes Heinz Isler and Antoni Gaudi used fabric as a modeling tool. These visionaries recognized that hanging chains and fabrics, forming catenaries, are in pure tension and when inverted are in pure compression and very stable. Gaudi, whose ing preceded the works of Candela... looked to nature and natural forms—an approach today called biomimicry..."

"Shells under compressive loading investigated under the assumption of perfect properties may be considered to be optimal structures. Their load carrying capacity is significantly larger compared to shells which show deviations in geometry, material behaviour, loading and boundary conditions. ...Unfortunately, comparatively little quantitative information exists about the initial imperfections in actual structures... One possibility to improve this situation is to perform systematic numerical simulations... Classical numerical concepts of the load carrying capacity of imperfect structures focus on the model of a perfect shell configuration and on the analytical estimation of unstable, postcritical equilibrium paths. This was first demonstrated by Koiter, whose postbuckling theory describes the nonlinear static load carrying behaviour of structures in the initial stages of buckling. ...[I]nitial unfavourable imperfections will lead to a reduction in load carrying capacity. This approach has certain restrictions as the results are evaluated by linearisation around the bifurcation point of the perfect shell. For the numerical simulation of the load carrying behaviour of imperfect shells it is commonly assumed that the initial geometric imperfections have the shape of the lowest bifurcation mode of the respective shell. ...In the cases of high imperfection sensitive shells [with] multi-mode-buckling... the lowest bifurcation mode is not always the ”worst” imperfection shape. Recently, a specific concept employing finite element procedures... directly evaluates the ”worst” imperfection shape and [is based upon] analysis of the imperfect shell space."

"Resistance of Spherical Shells to an Internal Fluid Pressure.—An elastic fluid contained in a closed vessel presses each unit of area of the surrounding walls with equal force. The resistance offered by the walls depends on their superficial area, their form, their thickness, and the coefficient of resistance of the material."

"The hollow sphere encloses the largest space in proportion to the superficial area of its shell, and all vessels that are not spherical, exposed to an internal fluid pressure, experience distortion on account of their tendency to assume the spherical form. A hollow sphere, having a shell of uniform thickness composed of a homogeneous material, experiences the same tension at all sections of metal formed by diametrical planes."

"The area of a [circular] diametrical section, S, of a thin spherical shell is very nearly given by formula:S = 2 \pi rtwhen t represents the thickness, and r = the inner radius of the shell, and t is supposed to be very small compared with r. The whole force, F, to be resisted by the tenacity of section S is equal to the excess of the internal fluid pressure per unit of area over the external pressure, into the area of the plane passing through this section, orF = \pi r^2 pAssuming that every portion of section S is equally strained by F, and designating by k the coefficient of the ultimate tenacity of the material of which the shell is composed, the bursting pressure will be found from the equation: \pi r^2 p = 2 \pi rtk; hencep = \frac{2tk}{r} { I.}and the proper ratio of the thickness to the radius of a thin hollow sphere is given by the formula:\frac{t}{r} = \frac{p}{2k}..."

"Resistance of Cylindrical Shells to an Internal Fluid Pressure.—The tension produced in a cylindrical shell by an internal fluid pressure may be considered as being of two different kinds—viz., first, a tension acting in a longitudinal direction, tending to pull the ends of the cylinder apart; and, secondly, a tension acting in a diametrical direction, tending to split the cylinder from end to end."

"The force, F, producing the first-named tension is represented by the formula:F = \pi r^2 p;and the sectional area, S, of a thin shell resisting this force may be represented with sufficient accuracy, as in the case of thin spherical shells, by the formula:S = 2 \pi rt.The value of p, when it becomes the bursting pressure, is found from the equation,r^2 \pi p = 2 \pi rtk; hence p = \frac{2tk}{r} { II.}the same as that of a spherical shell of equal radius and thickness."

"To find the value of p which would split the cylinder [of unity length] from end to end... The force tending to rupture such a ring at the sections formed by any diametrical plane is given by formula:F = 2rp,and the area of these sections byS = 2t.The bursting pressure is, therefore, found from the equation:2rp = 2tk; hence p = \frac{tk}{R}...only half as great as... equation { II.}"

"Resistance of Cylindrical Shells to an External Fluid Pressure.—Thin hollow cylinders exposed to an external fluid pressure never give way by direct crushing, but by collapsing; it may be assumed that, other things equal, the resistance of tubes to collapsing is greater as their form is more truly cylindrical and their shell more perfectly homogeneous."

"Fairbairn has deduced the following formula from experiments made mostly on very thin cylindrical tubes of various lengths and diameters—viz., for wrought-iron cylindrical tubes let l = the length, d = the diameter, and t the thickness of the shell, all expressed in the same unit of measure, and let p = the collapsing pressure in pounds per unit of area; thenp = 9,672,000 \frac{t^{2.19}}{l d}. { IV.}In case a tube is stiffened by T-iron rings or by flanges, l represents the distance between two such adjacent rings or flanges."

"Fairbairn finds that the collapsing pressure of... an elliptic form of cross-section is found approximately by substituting... for d the [following]... let a be the greater and b the less semi-axis of the ellipse; then we are to maked = \frac{2 a^2}{b}. { V.}"

"In an article in the Annales d'u Génie civil, March, 1879, on the “Resistance of Tubes subjected to an External Pressure,” by Théodore Belpaire, an attempt has been made to deduce a new formula for the collapsing strength of tubes. ...The writer ... considers the case of a tube with ends rigidly fixed, and supposes that under an external pressure it changes its form in such a manner that its generatrix becomes the arc of a circle, the centre of which lies on a perpendicular erected in the centre of the generatrix; and, neglecting, the elastic forces due to flexure or elongation of the fibres—which are very small as long as the curvature is slight—he investigates the shearing stresses; these attain their greatest value at the fixed ends. Calling S the greatest shearing stress, p the pressure in pounds per square inch, t the thickness of the tube in inches, L the length of the tube in inches, he deduces the following approximate formula for the external pressure which a given tube can bear with a degree of safety depending on the value attributed to S—viz.:p = \frac{2tS}{L}. { VI.}The writer deduces then a general value S from two experiments made by Fairbairn with elliptical tubes, because the uncertain and variable elements of strength due to the cylindrical form and to homogeneity of the material do not enter here. When the factor of safety in the foregoing equation is to be four, the value of S becomesS = 428,394 \frac{t}{D} - 7,111,550 (\frac{t}{D})^2;...With reference to those cases where the factor of safety exceeded four greatly, the writer claims that the high pressures necessary to produce collapse indicate merely the great increase of strength derived in the particular instances from the uncertain element of circular form."

"The problem of curved plates or shells was first attacked from the point of view of the general equations of Elasticity by H. Aron. He expressed the geometry of the middle-surface by means of two parameters after the manner of Gauss, and he adapted to the problem the method which Clebsch had used for plates. He arrived at an expression for the potential energy of the strained shell which is of the same form as that obtained by Kirchhoff for plates, but the quantities that define the curvature of the middle-surface were replaced by the differences of their values in the strained and unstrained states."

"E. Mathieu adapted to the problem [of curved plates or shells ] the method which Poisson had used for plates. He observed that the modes of vibration possible to a shell do not fall into classes characterized respectively by normal and tangential displacements, and he adopted equations of motion that could be deduced from Aron's formula for the by retaining the terms that depend on the stretching of the middle-surface only."

"Lord Rayleigh... concluded from physical reasoning that the middle-surface of a vibrating shell remains unstretched, and determined the character of the displacement of a point of the middle-surface in accordance with this condition. The direct application of the Kirchhoff-Gehring method led to a formula for the potential energy of the same form as Aron's and to equations of motion and boundary conditions which were difficult to reconcile with Lord Rayleigh's theory. Later investigations have shown that the extensional strain which was thus proved to be a necessary concomitant of the vibrations may be practically confined to a narrow region near the edge of the shell, but that, in this region, it may be so adjusted as to secure the satisfaction of the boundary conditions while the greater part of the shell vibrates according to Lord Rayleigh's type."

"[P]rinciples as developed by Kelvin and by Love show that it is impossible to bend a nearly flat dish shaped shell about one horizontal axis without at the same time bending it in the opposite direction about a second horizontal axis at right angles to the first."

"[P]icture... a circular piece of a plate which has an approximately spherical curvature at its center point O. Pass a plane XY tangent to the surface at O and let OZ be normal to it at O. Then if a be applied about OX it will not only make the curvature of the plate greater in the plane ZOY but at the same time it will make its curvature less in the plane ZOX to an equal amount as is evident by experiment on a shell of any elastic material, and as is proven in Gauss' theorem of the curvature of thin shells. Since the force applied to produce the given bending moment must produce both these equal changes of curvature simultaneously by producing elongations and compressions in twice as much material as in a plane plate of equal cross section, each of them is only half as great as would be produced in a plane plate in a single direction by this same moment. Hence it. appears that the deformations produced by an applied moment are not more than half as great in a spherical dish shaped plate as in a plane plate..."

"The at any point P of a curved surface is most readily measured by finding the radii of curvature of two curved plane sections of the surface made by a pair of planes drawn normal to the surface at P and at right angles to each other. Normal planes are those perpendicular to the surface at P, and they intersect each other in the normal to the surface at P. If R is the radius of curvature of any plane section at the point P, then 1/R is defined as its curvature at P. At every point of a convex surface there must, except in case when the curvature of all of the sections is the same, be some one of the normal sections in which the curvature is the greatest, and also another section in which the curvature is least. These are called principal planes and s. According to Euler's Theorem these principal sections lie in normal planes which are at right angles to each other, and further, the sum of the curvatures of any pair of rectangular normal sections whatever, at a given point P is constant, so that in rotating a pair of normal planes that remain perpendicular to each other about the normal the increment of the curvature of either normal section is equal to the decrement of the other, and the sum of the two normal curvatures is equal to that of the principal curvatures."

"In his great treatise on the Mathematical Theory of Elasticity Love, following the original investigations of Gauss, demonstrates... that when a piece of a thin elastic shell or plate that has a spherical curvature of 1/R is deformed by a small bending without stretching, then in the case of initial spherical curvature one principal curvature of the deformed surface will exceed the initial curvature 1/R by the same amount as the other will be less than l/R. That this is the fact in this case seems evident without following the abstruse analysis of Love... because if x and y be lines drawn tangent to two rectangular normal sections at P, and the spherical surface be bent slightly about x so as to alter the curvature of the section in the normal plane at right angles to x by alternately increasing and decreasing it, it is evident from symmetry that the curvatures of the section in the normal plane at right angles to y will undergo at the same time alterations of curvature which are equal and opposite to those in the first normal plane, altho this equality does not in general hold true in shells that are not spherical in shape. Nevertheless, the same statement evidently holds true for surfaces of revolution about the normal at P as an axis."

"[C]onsider the bending moments that must be applied to produce such a deformation. It is evident from the fundamental equation EI/R = M of the ordinary theory of thatEI\;d(\frac{1}{R}) = dMis the equation which expresses the relation between the increment (or decrement) of curvature d(1/R) and the increment (or decrement) dM of the applied moment which produces this change of curvature about x (or y) in which the value of I may be calculated in case of only slight curvature just as in a flat plate."

"It is evident that in order to produce this kind of deformation it is sufficient to apply one positive and one negative moment increment, each of the same magnitude dM, simultaneously about each of the rectangular axes x and y, respectively. These moments produce elongations and shortenings in the exterior and interior fibers of the plate or shell independently in two directions at right angles to each other in the same manner as in a beam but none whatever are produced in the neutral surface, so that the resistance that is offered to this bending arises from the resistance which the fibers offer to such elongation and shortening. The principal curvatures of the surface after bending will be 1/R + d(1/R) and 1/R - d(1/R) respectively."

"[S]uppose a uniform thin-walled hemisphere... is subjected only to its own weight, and is supported round its [base] by forces which produce compressive stresses σ. If the shell has radius a and thickness t, and the material has unit weight ρ, then [the force applied to the base is equal to the weight of the structure, where 2\pi a is the circumference and 2\pi a^2 is the surface area of the hemisphere]\sigma(2\pi at) = \rho(2\pi a^2t) or [dividing by 2\pi at] \qquad \qquad \qquad \qquad \qquad \qquad \qquad \qquad \qquad \sigma = \rho aThus the compressive stress necessary to support the dome has a magnitude independent of the thickness of the dome. ...Now the expression \rho a ...is typical of the order of magnitude of stresses in more general shapes of shell... [I]t may be expected that externally applied loads will at most equal, and will usually be less than the self-weight loads of shells of reasonable size. ...Thus stresses resulting from snow or wind may be expected to be of the same order as those resulting from dead load."

"Very thin shells may be in danger of locally. The problem hardly arises for civil engineering applications over moderate spans, but may be very important if the spans are very large. Local buckling of a thin shell will occur at a typical stress\sigma_{cr} = kE \frac{t}{R}where E is [and R is the minimum radius of curvature of the shell]. The value of the constant k varies from author to author, but a reasonable value is about 0.25. Thus for a concrete shell for which E is about 20 000 N/mm2, and for which \frac{t}{R} is as small as 1/1000, the critical stress is determined as say 5 N/mm2."

"[S]ome will claim that they give the best service to engineers by concentrating mainly on the form and structure of the governing equations... for once the foundations have been laid properly (they say), the solution of all problems becomes merely a mathematical or computational exercise... and indeed unless the foundations have been laid properly (they say), any resulting solutions are of questionable validity. Another group will argue... they can serve engineers best by providing a set or 'suite' of computer programmes, which are designed to solve a range of relevant problems... and... such programmes renders obsolete... the theory of shell structures... I have rejected both... the important thing is for engineers to understand how shell structures behave..."

"Any load which is applied to the shell is sustained in general partly by the stretching surface and partly be the surface; and the balance in load-sharing is regulated mainly by the 'interface pressure' between the two surfaces, which varies from point to point over the surface. This interface pressure becomes a prime variable of the problem. In terms of classical it is a variable 'redundancy'."

"Gauss (1828) pointed out that there are two distinct but complimentary ways of thinking about the of surfaces. ...this point ...is absolutely fundamental to a clear understanding of the subject. Gauss's dual view of curvature fits precisely the 'two surface' description, and it provides succinctly the geometrical conditions which are necessary if the deformation of the two surfaces is to match. The key variable in this connection turns out to be a scalar quantity; and paradoxically... conventional treatment... in terms of general is... too elaborate to reveal this crucial... quantity."

"The development of the plastic theory of structures from the 1930s onwards was healthy not only because many real materials are still structurally useful when they have passed beyond the elastic range, but also because the new theory was able to shift the emphasis... to more profound questions about the kind of information which the engineer requires in order to design satisfactory structures. ...plastic theory can contribute to the understanding of the response of shells to localized loading."

"The essential ingredients of a shell structure are continuity and '. ...an ancient masonry or vault is not obviously continuous... it may be composed of separate... sub-units or s not necessarily cemented... But in general... are held in a state of compression throughout... thus in compressive contact... [S]hells are structurally continuous in the sense that they can transmit forces in a number of different directions in the surface of the shell, as required. These structures have a quite different mode of action from skeletal structures... [which are] only capable of transmitting forces along their discrete structural members."

"[T]he basic model of a shell which we shall use... takes as its first step the replacement of a shell by a surface... [M]uch of the detail of the stress distribution will be suppressed precisely in the step of shrinking the three-dimensional physical shell into a zero-thickness surface. ...[T]he 'surface' theory... is extremely simple in comparison with other theories... [T]he regions in which the theory is inadequate are all highly localized, and there are very many practical problems in which... the local details are either unimportant or else can be treated more or less in isolation. All if this is closely analogous to the classical methods for analyzing beam and frame structures."

"The analysis and design of shell structures is of interest in... the design of large-span roofs, liquid storage facilities, silos... pressure vessels, including nuclear reactor containment vessels and pipes... structural design of aircrafts, rockets and aerospace vehicles. All... require the analysis and design of shells... [T]he derivation of equations for plates or shells is only an extension of... bars or beams, based on equilibrium, , and . ...Using the understanding of shell behavior... including the approximate methods and... tables for quick solutions... a reader may be able to judge the computer results, before designing a shell structure. ...Theory of circular rings, concepts of stress resultants and middle surface are... introduced... Circular also forms an intermediate step for a gradual introduction or transition to shell analysis from the analysis of bars and beams."

"[A] shell element will have, in general, 10 unknown internal stress reactants... [B]y making suitable assumptions, we try to obtain simpler a solution... for practical purposes. We first assume that the shell is thin. Such shells are... very flexible for resisting bending moments and shearing forces. ...We would always prefer the shell to resist any loading by development of in-plane forces... we assume that the moments Mx, My, Mx,y and My,x are zero... Then, by taking moments about the x- and y-axes... we conclude that Qy and Qx must also be zero, and by taking moments about the z-axis, we get Nxy = Nyx. Thus there remain only three unknown internal stress resultants, Nx, Ny, and Nxy, to support a given loading. Also... three equations of equilibrium\sum_{} F_x = 0 \quad \sum_{} F_y = 0 \quad \sum_{} F_z = 0...determine the three unknowns. Such simplified theory... is called membrane theory, as opposed to the more general and complex bending theory..."

"[W]e can consider the general equation for the deflection [w] of a shell as\mathcal{L}[w(x,y)] = f[p(x,y)]where \mathcal{L} is a and f[p] is some function of the given loading p. The general solution... will bew = w_h + w_pwhere w_p is the particular solution... that satisfies equilibrium and compatibility at all internal points... but not necessarily satisfying the boundary conditions. ...w_h is the solution of the homogeneous equation with p = 0 (...only edge loads can be present). ...[F]or solving practical problems, we can [find] w_p...by assuming moments and shears to be zero... the "membrane solution." ...similar to obtaining (fairly correctly) the forces in Truss members by assuming moments and shears in the members as zero (i.e., assuming the joints are perfect pins)... For obtaining w_h... we must... use the exact differential equation... the "bending theory" solutions... Fortunately, for most types of shells, they die out quickly as we move away from the boundaries. ...[O]ur general procedure ...obtain membrane forces under a given loading... then superimpose... the bending theory solutions for edge loads. ...[T]he membrane and edge-load solutions together satisfy the boundary conditions; i.e., the edge loads are obtained by solving equations of compatibility at the boundaries."

"A revival of interest in curvilinear structures is under way... es, vaults, and thin-shelled structures must be re-discovered. ...Why is there a revival in shell structures, and where might it lead? Cost factors, materials availability, labor supply, housing crises, solutions to domestic and Third World problems all play a part... With today's almost unlimited computer technology and the knowledge that can be gained from understanding s and vaults built both in the past and present, it is hoped that this work on the practical aspects of designing curvilinear forms will contribute to further exploration and encourage the application of thin shells..."

"A thin shell is a special kind of vault whose geometry may include many shapes. ...a three-dimensional form made thicker than a membrane, so that it can not only resist tension as membranes do, but also compression. On the other hand, a thin shell is made thinner than a slab, which makes it unable to resist bending, as a slab does. In short, thin shells are structures thicker than membranes, but thinner than slabs. Thin shells are made possible by the use of materials that work well under tension and compression. Masonry has no tensile strength... Only the availability of and made a thin shell possible."

"The of a shell can be of the same sign throughout... In such a case the surface is called synclastic. s are synclastic surfaces... The curvature of a shell can also be of a different sign... both concave and convex... which is known as anticlastic. An example... is the hyperbolic paraboloid."

"While size and support conditions have an important bearing on the degree of accuracy needed in the analysis, the distribution of load has a less important effect on stresses. This is due to the fact that s in the shell are more closely related to the boundary conditions than to the load. Hence, it is usually unnecessary to analyze a thin shell for partial live loads even though the supporting members must be analyzed for such partial loads. For this reason, snow load on thin shells may be assumed either uniformly distributed on the horizontal projection or uniformly distributed over the surface of the shell. On the other hand, local bending moments due to large concentrated loads on the shell must be considered."

"Shells of double curvature both the synclastic... and anticlastic... are inherently better suited to resist loads by direct forces than are shells of single curvature. The reason for this is obvious from the fact that this type of shell possesses arch action along both curvatures. But in order that surfaces curved in two directions behave as a shell, it is important that proper support or edge members be provided. The direct stresses throughout the major portion of the shell are usually of little significance except as they relate to . A careful evaluation should be made of the bending moments produced in the vicinity of the edge members by the interaction of the edge member and the shell. For moderate size shells, this effect usually is confined within a few feet of the vicinity of the edge member. ... An exception to this are some anticlastic shells, like the hyperbolic paraboloid, wherein bending can prevail throughout a greater portion of the shell. To a limited extent, this also occurs in s, when the supports do not provide a reaction tangent to the shell surface. In these cases, the bending moments may extend a significant distance into the shell."

"The great era of thin concrete shells... was an attempt to cover large spans with the most widely used construction material of the Twentieth Century and yielded structures that are now regarded as architectural masterpieces. The design of thin concrete shells also fostered theoretical developments in , in the mathematical theory of shells and in the theory of finite elements."

"In Belgium, the key figure in the design, construction and popularisation of concrete thin shells was certainly André Paduart (1914-1985). ...Paduart was also and particularly an active member of the International Association for Shells Structures (IASS) founded by E. Torroja in Madrid in 1959. ...[He] organized in Brussels in 1961 one of the very first symposia of this association... Shortly after, he published [1961] in French a remarkable small book covering essential theory, design and construction of thin concrete shells [Introduction au calcul et a l' exécution des voiles minces en béton armé]... translated in English [Introduction Shell Roof Analysis] in 1966..."

"[A] significant breakthrough was achieved with... two celebrated huge airship hangars built by Freyssinet at Orly in the early 1920s... [whereby] the principle of the corrugated form for the concrete shell was introduced to obtain the necessary stiffness..."

"Cylindrical s have probably been the most used form of concrete shells. The reconstruction after the devastations of the Second World War required forms of building which offered economy of material. This gave an enormous boost to the use of shell roofing... since materials... were in short supply... [N]early 50000 square meters of warehouses at the docks of harbour [were built] between 1947 and 1950...by [André] Paduart and [C.] Wets... [H]angars were built 1950-1952 at... airfields... one arch of a hangar under construction at Chièvres collapsed... a [short] time after decentering. ...[M]easurements made in the early 1990s [indicated that] several of the [arches] at Chièvres ...were significantly deformed."

"For the 1958 Brussels international exhibition, Paduart and architect J. Van Dooselaere received an official commission... to design a structural symbol testifying of the "victory of [Belgian] civil engineering over nature"... The final structure... the "Civil Engineering Arrow" [Pavilian of Civil Engineering], was a spectacular thin wall... cantilever beam... a bold impression of equilibrium and "tour de force". [They] received the 1962 Construction Practice Award for their "Arrow". ...dismantled in 1970."

"Paduart was working at the edge between academia and engineering practice. ...[H]is production during thirty years... is eclectic, with s, corrugated shells, hypar shells and folded plates. He could teach... mathematical theory of shells at the university, but used... very simple methods derived from the Strength of Materials to design his own shells. This did not deter him from conceiving bold structures, at the limits of the utilization of the materials and construction techniques of his time, but he looked always forward with anxiety to the decentering of the shells..."

"Shells can be singly curved (e.g., cylinders and cones) or doubly curved (e.g., sphere or hyperbolic paraboloid)."

"[A] hyperboloid of one sheet... is often used for s, because it can be formed of straight lines... Another doubly curved shape formed of straight lines is the ... for which a straight line travels along another straight line at one end and a curve at the other end."

"At any point on a surface, there are two principal radii of curvature that uniquely define the surface. Of all the curves on the surface that can be drawn through the point, the two principal radii of curvature will be the maximum and minimum that can exist at the point. The maximum radius of curvature for a is infinity, while [its] minimum is the radius of the circle..."

"[Take] two pieces from the outside and inside of a , respectively. In the former, both radii of curvature lie on the same side of the surface, and [so] the curvature is considered positive, while in the latter they are on opposite sides of the surface, and [therefore] the curvature is negative."

"All shells have either positive (bowl-shape) or negative (saddle-shape) curvature. ...Positive curvature shells are subject to , as the entire shell is subject to compression forces. In contrast, material failure is more common in negative curvature shells with brittle materials such as concrete."

"The structural analysis of shells has had a long and difficult history."

"Shells were developed and reached their peak popularity just before the ready availability of computers and the FE method."

"The analysis of shells requires that the three conditions of equilibrium, compatibility, and constitutive laws be satisfied simultaneously. The latter are the stress-strain properties for the materials.... Most shells are designed with isotropic materials."

"With the development of advanced composites, their orthotropic and anisotropic behavior must be considered. However, composites have not been used for architectural shells to date."

"Roof structures are seldom designed for dynamic loads. Earthquake and wind loads may be treated as equivalent static loads."

"The above three conditions result in three partial differential equations, two of the 2nd order and one of the 4th order, for the most general case with two different radii of curvature and with combined bending and membrane actions. An early representation of these equations for cylindrical shells may be found in Donnell (1933). Bradshaw... extended those equations to the general case of double curvature, which can describe any 1D member (beam), 2D member (plate), or 3D singly or doubly curved member (shell)."

"If the 4th order -related terms are left out, the equations will represent only the membrane action, which is usually sufficient for part of the shell away from the s because flexural resistance of thin shells contributes little in this region."

"Equal radii of curvature result in equations for a . Equations of a cylindrical shell are derived when one radius of curvature is set to infinity; when both are set to infinity, it will result in bending of a flat plate. Finally, the ordinary differential equation for bending of a beam is derived when plate width is set to unity."

"Stress analysis of complete shells, such as s, is much simpler than for architectural roofs because of the boundary conditions."

"When the shell is a portion of the sphere, it tends to spread outward at the discontinuous edge. To counteract this a ring is added, but the ring and the shell distort by different amounts, which results in stresses in the shell. These incompatible strains must be reconciled analytically, which is not too difficult a task for simple spherical shells. However, when the shell has isolated supports and few (if any) planes of symmetry, it is a severe problem..."

"The resulting disturbance at the edge may be thought of as causing stress redistributions to flow across the entire shell with diminished effect as they move away from the edge."

"In many cases... the stresses resulting from the discontinuous edges will dominate the design."

"Ribs are frequently added at the edges, though visually disruptive. One of the graceful aspects of Candela’s shells is their lack of ribs. It is also possible to design the shell with the rib integrated within the shell itself."

"There is a remarkable property of shells supported vertically at their edges. [Take] a spherical dome supported on a wall. A tension tie is required around the perimeter at the intersection of the dome and the wall. This tie will be funicular, i.e., it will only carry axial tension forces. This principle has been known since antiquity for circular domes and ties. However... the tie will be funicular for any shape of either the plan or elevation (Csonka 1962) provided that the shell has positive curvature and continuous vertical support. The support may be a continuous wall or stiff beams between adequately spaced columns. ...The thrusts are taken by shear forces through the width of the shell, and only tension forces exist in the tie."

"Beles and Soare... have reported [on] buckling failure of shells. Unlike shells of positive curvature that are subject to buckling, in shells of negative curvature, such as hyperbolic paraboloids, buckling is prevented through the tension curvature in the other direction."

"Virtually all studies on shell buckling have focused on cylindrical, conical, and spherical shells made of metals, and usually on full 360° models rather than the much more complex architectural shells. ...Applicability of these tests to large-scale concrete shells... is questionable."

"Initial imperfections in shells can result in their at loads far below their theoretical capacity. Once a shell buckles, its collapse tends to be complete, contrary to plates, which have high post-buckling capacity."

"When is placed on a , the weight distorts the balloon. This means the shell will not be exactly the initial shape of the balloon. This is not important for a small span shell. For a long span shell, however, this deviation from the spherical shape could be serious as shells are sensitive to buckling due to the initial roughness effect."

"Shells were seldom the most economical way of covering a large space, especially when compared to lightweight tension membranes. ...[F]ormwork has always been a major cost factor."

"There are... new materials such as fibercrete concrete and fiber reinforced polymer (FRP) composites that may be used in shells."

"When designed properly, [shells] are among the most beautiful and efficient of architectural structures. They will present both problems to be solved and opportunities to create for those who take the time to understand them."

"This is a Manual on low cost, permanent shelter for needy families built using unskilled labor."

"This construction is a means of fighting poverty. The work can unite war torn communities, and communities disoriented by natural disaster."

"Thin shell latex concrete shell roofs are one answer to low cost construction of immediate shelter of displaced people groups. liquid and are generally available in... regions where poverty and the need for housing abound."

"An LC HP shell is an HP shell made of latex concrete. Latex concrete is fiberglass fabric stretched over a large frame... and the resulting fabric surface is then saturated with first a slurry of latex and Portland cement (a liquid paste), then when that dries, a ¼ to ⅜ inch thick layer (or layers) of latex concrete made of latex liquid, Portland cement, and dry sand is broomed on."

"The latex concrete is typically made by mixing Portland cement with dry sand to a 1 to 3 ratio by weight, then adding latex liquid until you get a broomable mix."

"Latex liquids are a mixture of polymer latex solids suspended in water... typically at a mix of about 50 percent solids to 50 percent water by weight. This material is then used by manufacturers of construction liquids such as latex paints and cement additives by adding additional water, coloring, and special chemicals such as antifoaming agents. ...[T]rade named materials ...all have properties in common. They improve mechanical strength and adhesion properties, and impart the ability of the concrete to air cure. They remain stable in Portland cement, and resist the penetration of water, hence provide ...good freeze-thaw resistance, and low moisture penetration. They can readily bond with themselves. Latex paints are typically... 20 percent solids by weight... [cement additives] are... about 47 percent solids."

"The strength of latex concrete is [negatively] affected by excess water in the mix. For that reason it is best to work with dry sand. ...[I]f you add the latex to wet sand, you will be watering down what latex you have, and not getting the advantageous physical properties ...Use dry sand. ...Try for a ratio of polymer solids to cement by weight of 0.12 to 0.15, and a water to cement ratio by weight of 0.35 to 0.38."

"The construction of thin concrete shells ended abruptly at the end of the 1970s, mainly caused by the high costs... However, uncertainties in the structural behaviour of shells did not help either. Contemporary progress in finite element software discards these uncertainties as it allows the engineer to closely approach the actual behaviour of thin concrete shells by performing geometrically and physically nonlinear finite element analyses. ...The combination of advanced finite element analyses and ultra high performance fibre reinforced concrete may lead to shells with even greater spans and thinner thicknesses than achieved so far."

"Shell structures have been constructed since ancient times. The Pantheon in Rome and the in Istanbul are well-known examples. After the Roman times the traditions of domes continued up to the 17th century. Since then they seemed forgotten. Stimulated by the newly developed reinforced concrete and the demand to cover long-spans economically and column free the shell made a comeback in the early 20th century. and Ulrich Finsterwalder designed in 1925 the first thin concrete shell of the modern era, the Zeiss planetarium in Germany. The modern era of shell construction is recognised by the trend towards greater spans and thinner shells. Guided by well-known engineers as , Eduardo Torroja, Anton Tedesko, Nicolas Esquillan, and a blooming period of widespread shell construction took place between 1950 and 1970. Shell construction suddenly vanished at the end of the 1970s, mainly caused by the high costs [relative] to other structural systems. Moreover, inflexible usability and uncertainties in the structural behaviour of shells and difficulty of proper analysis methods did not help[,] neither did the stylistic identification with the 1950s and 1960s. Today the great era of thin shells is over, however, nowadays natural free-form shapes and blobs attract more and more attention. In addition, recent developments in concrete technology have led to ultra high performance fibre reinforced concrete with revolutionary performance in tension and compression. Eventually this may lead to a revival of the thin concrete shell."

"In case of a failure, the shell may fail due to large deformations (buckling) or due to material nonlinearity (cracking and crushing) or by a combination of both (so-called inelastic or plastic buckling). ... Opposite to columns and plates, shells experience a sudden decrease in load carrying capacity after the bifurcation point (which can be obtained by a simple linear buckling analysis). ...compound buckling ...refers to several buckling modes associated with the same critical load. In the postbuckling range the modes... start to interact resulting in a significantly reduced load carrying capacity. As discovered by Koiter... geometrical imperfections in the shell cause the bifurcation point never to be reached and lead to... buckling at a considerably lower load. The size of the imperfections determines the limit load at which the shell fails. In case of plastic buckling, the fall-back is further intensified by material nonlinearity."

"[T]wo primary research questions can be formulated: [1] What is for a shell of hemispherical geometry, with given material properties, given support conditions, and subjected to a given load, the knock-down factor which indicates the difference between the linear critical buckling load and the actual critical buckling load taking into account imperfections and geometrical and physical nonlinearities? ...[2] Can high strength fibre reinforced concrete add to the trend towards greater spans and thinner shells with possibilities for even more slender structures? To obtain an answer to the research questions a series of analyses (linear elastic, stability, geometrically nonlinear and geometrically and phy sically nonlinear) is performed on a given hemispherical shell: the Zeiss planetarium shell."

"In the early twentieth century was a new building technology. Its novelty inspired experimentation, both from architects, such as Le Corbusier, and from engineers, who dreamed up different applications for the new ferroconcrete. One application for reinforced concrete that developed rapidly was its use in thin shells. These shells spanned great distances or stretched out in dramatic s, their thinness seemingly impossible for the distance they extended. This technology quickly grew ever more common, especially in long-span utilitarian settings, where thin shell concrete was able to cover large areas economically."

"The German engineering firm of ['s]... design of the concrete dome for ’s Century [or Centennial] Hall in Breslau... in 1913... became the first modern building whose clear span exceeded Rome’s Pantheon. Other notable structures of this early phase are the elegant works of Eduardo Torroja in Spain, including the Algecira market hall (1934), and Freyssinet’s economical segmented system for an aircraft hangar at Orly (1921)."

"By the 1970s the use of thin shell concrete had all but disappeared... This change was due to a combination of [economic] factors... This disappearance was also caused by the design challenges [of] thin shell concrete. Shell structures, because of their thinness, must be shaped to conform to the forces present in the structure. Until recently this shell form-finding could only be done... with specialized computer expertise, or through... physical model testing and measurement. ...In recent years ...simple computational models ...have been adopted ...to explore rapid form-finding in ...early design phase."

"Forces present in the structure, shape thin shell concrete. Areas of uniform load present smooth, catenary curvatures, while areas of concentrated force express themselves as sharp bends or spikes in the surface form."

"By their very nature all funicular structures, including thin shell, use... less material... By designing only for pure tension or compression these structures experience very little force. These pure forces require less material to resist..."

"Dieste’s hypar masonry roofs are inexpensive, utilitarian statements about space enclosure..."

"[T]he second wave of shell building (1940-1960s)... focused almost exclusively on s... [to] include s and hyperbolic paraboloids. ...[T]hey were definable through mathematical formulas, which allowed the designer to understand the forces... Ruled surfaces are... more constructible, because they can be created out of linear elements, such as... boards and pipes..."

"The most prominent designer to eschew s is the Swiss engineer . In 1954... Isler hit on the idea that a “bubble” (in this case a pillow) takes the optimal shape for its edge boundaries. Isler began to construct models by inflating surfaces or by hanging and then hardening them."

"I have selected the use of hanging models to simulate compressive forces. This is one of the longest-used form finding techniques. It has its roots in physical models, but in recent years it has also given rise to a range of digital tools that are fairly accessible to an uninitiated designer... Hanging models... can be used to simulate... funicular structures. ...derived from the Latin word for “rope”... a structure takes its shape in response to the magnitude and location of forces acting upon it. For example, a rope suspended from two level points will form a “V” when a single point load is added at midpoint, but will form a catenary when under an evenly-distributed load. While a suspended rope is a purely tensile system, if inverted and made rigid that same form converts into a system that is in pure compression. This was first postulated (and wonderfully expressed) by the English scientist Robert Hooke... The value of a structure that is purely in compression is that it experiences no due to structural loads. With no bending present materials can be used very efficiently, allowing for the use of extremely thin elements... materials that are strong in compression... as tiles or masonry, can... be employed."

"History shows that not all thin shell concrete buildings are funicular—other families... chosen for pragmatic reasons such as their constructability, or because they were geometrically simple enough [that] through calculation... bending... was [found to be] within... tolerances... for the material."

"[T]he infill fields of a Gothic cathedral’s ing behave as masonry shells, and by the 1860s masonry s of great beauty were developed by in both Spain and the United States. Gustavino’s work and graphic design methods... influence[d] Antonio Gaudí... whose work has been shaped by an interest in force-derived architectural form. While early engineers such as Guastavino pushed unreinforced masonry’s limits in thin shell construction, it was the introduction of steel reinforcement, initially in concrete, that sparked the Twentieth century’s interest in thin shell construction. Early [twentieth century] shell-builders were often engineers, and were engaged to design economical long-span structures... as aircraft hangars, train sheds and factories."

"[A] list of factors combined to make thin shell concrete a less desirable solution for long spans by the 1970s. ...material efficiency could no longer off set the labor premiums demanded by complex formworks ...shapes were more difficult to create when an insulating layer was required ...A third challenge posed to compressive structures ...was the rapid development of s. ’s experiments with tensile membranes were mature enough in 1972 that they were used on Munich’s Olympic Stadium."

"Shells play a special, singular role for engineers. Their shape directly derives from their flow of forces, and defines their load-bearing behaviour and lightness, saving material by creating local employment, their social aspect. This is especially true for thin concrete shells with their characteristic curvatures: single curvature (cylindrical and conical), synclastic (dome-like), anticlastic (saddle-like) of free (experimental). If well formed, there are no bending but membrane forces only (axial compression and tension)..."

"The shell designer seeks forms to carry the applied loads in axial compression with minimal bending forces. The earliest example of structural form finding for an arch was published by the English engineer and scientist, Robert Hooke... 1676... As hangs the flexible line, so but inverted will stand the rigid arch. ...'Hooke's law of inversion', can be extended... and considered for shell structures of various geometries. In the context of shell structures, the term funicular means 'tension-only' or 'compression-only' for a given loading, typically considered... Unlike the case of the hanging cable with a single funicular form... hanging membranes have multiple possible forms. ...[T]he three dimensional shell can carry a wide range of different loadings through membrane behaviour without introducing bending. ...[A] three-dimensional model of intersecting chains could be... used to design a design a discrete shell, in which elements are connected at nodes, or the model could be used to help define a continuous surface. If hanging from a circular support, the model-builder could create a network of meridional chains and hoop chains. By adjusting the length of each chain, various tension-only solutions can be found... Once inverted, this geometry would represent a compression-only form. Such... would quickly illustrate that many different shell geometries can function in compression due to self-weight."

"Today, most engineers fear shells and domes: they are mysterious and difficult to assess and master. ...Historic arches, shells and vaults are too easily seen as risks instead of opportunities. Under the motto of 'safety', these structures are destroyed and replaced by common beam-column systems. This is regrettable: their great historic and aesthetical value is lost forever. A better understanding and assessment of their structural behaviour holds the key to their conservation. ...[S]hells and arches are highly efficient structures."

"A collander... contains holes for draining food, but these holes do not stop it from being a shell. A sieve... is made from a large number of initially straight wires which are woven into a flat sheet and then bent into a hemisphere. It is also a shell, a gridshell. ...The spider web is essentially flat and made up of straight elements and when the wind blows, it bows outward like a sail and becomes curved. ...We call this a 'form-active' structure. This feature is characteristic of tension structures. The sieve may be in tension, compression, or a mixture of the two, but appears rigid. It does not significantly adjust its shape to the applied loading and, therefore, we call this a 'form-passive' structure. Where it is in compression, deflections lead to a structure becoming less able to carry the load, possibly leading to buckling. Columns carry loads via axial forces, but bending stiffness is required to stop buckling, and so it is with shells, although with shells buckling is resisted by a combination of bending and in-plane action."

"The hyperbolic s are associated with nuclear and thermal power plants... they are also used... in some large chemical and other industrial plants. [T]hey are high rise structures in the form of doubly curved thin walled shells of complex geometry..."

"The... structure is made of high-strength Reinforced Cement Concrete (RCC) in the form of hyperbolic [thin shell standing on diagonal, meridional, or vertical supporting columns and radial supports. The shell is sufficiently stiffened by upper and lower edge members."

"The hyperbolic form of thin-walled towers provides optimum conditions for good aerodynamics, strength, and stability."

"[T]he first cooling tower shell [to be] analyzed by means of a shell bending theory [was in 1967]. ...Because of the complex geometry of the cooling towers and also the classical methods of analysis of shell structures, the most preferred method of the modeling and analysis of NDCT [natural draft cooling towers] is [the] (FEM)."

"Deformation response and ultimate strength of RC shell structures are governed predominantly by material response of concrete and reinforcing steel, tensile cracking of concrete, [and] bond between concrete and steel.... Softening response of concrete due to quasi-brittle cracking in tension also... influences the nonlinear response by inducing loss of strength and stiffness... Due to all [of] these, analysis requires attention for realistic modeling of the layer of shell concrete confined between the reinforcement layers. ...[O]ne of the most challenging areas... is the modeling techniques using the layered elements."

"The NDCT [natural draft cooling tower] shell structures are submitted to environmental loads such as wind, earthquake and thermal gradients that are in nature. The dead loads, settlement, and construction load are... common... and various accidental loads, e.g., explosion [are]... experience[d]... in their lifetime."

"The meridional directed forces developed in [a] tower shell due to the self-weight... may cause local (diamond-shaped) buckling or axisymmetric circular buckling... Overall buckling of the tower shell may [be] caused by combination[s] of wind load and self-weight..."

"[I]n 1967, closed-form expressions [were] derived by Gould and Lee... for determining the resultant stresses in the shell and corresponding deformations under static seismic design load."

"[A c]ooling tower is normally designed for stagnant ambient air condition, but experimental observation showed that cooling efficiency... might decrease to 75 percent in the range of moderate to high wind velocity..."

"Experimental and numerical observations identically showed that heat transfer capacity of the cooling tower proportionally increased with wind velocity up to 3 m/s, and then decreased for higher wind velocity..."

"Concrete shell structures, often referred to as ’thin shells’ are suitable structural elements for building spacious infrastructures. ...Loads acting on the surface of shell structures are mainly carried by the so called membrane action. This is a general state of stress [which] consists of the in-plane normal and resultants only. In comparison, other structural forms such as beams and plates carry loads acting on their surfaces by action, which can be said [to be] structurally less efficient. Usually the in-plane stresses in shells are low such that with a relatively small thickness it is possible to span over large distances."

"Compared to structural elements such as beams, slab and walls, the structural behaviour of shells in not easy to predict. Hence evaluating the accuracy of the results obtained from FEA of shell structures is a challenging task. Having the knowledge and understanding of the analytical solution method can provide the basis for this verification and... give ...much needed insight into the structural behaviour of shells. ...for some of the most commonly constructed concrete shell structures, a complete analytical solution procedure is available. The two types of concrete shell structures considered in this paper are axisymmetric shells and cylindrical shell roofs. ...[A]xissymetrical shells include structures such as containment buildings, tanks and silos. ...[C]ylindrical shell roofs are often preferred structural elements for large span concrete roof structures."

"A shell can be defined as a body that is bounded by two surfaces parallel to its middle surface, and is deformed in any arbitrary manner. This is true for shells of a constant thickness... considered in this study. ...One particular way of classifying shell surfaces is according to their Gaussian curvature. \kappa_g = \kappa_1 \cdot \kappa_2 = \frac{1}{r_1} \cdot \frac{1}{r_2}Another way of describing shell surfaces is according to how the surfaces are generated. Using this method, in 1980 classified shell surfaces into Geometric, Structural and Sculptural surfaces. Geometric shells are well defined mathematically and... easily calculated analytically. These type of shells were quite significant in the development of shell structures [when] computer[s]... were not available. ...geometrically shell surfaces can be classified as cylindrical... spherical... conical... paraboloidal... etc."

"[C]losed surfaces are more rigid than open surfaces. ...Therefore to achieve ...rigidity the openings [are] compensated."

"[U]sing concrete shells as roofing provides the possibility of constructing spacious columnless buildings... has enhanced this possibility."

"Concrete shells can be built by the assembly of several cast units, or cast in one piece (monolithic). Monolithic concrete shells are structurally stronger..."

"[D]evelopment of the theory employs (elastic material), equilibrium and compatibility. Hooke’s law relates strains with stresses, equilibrium relates stress resultants with external loading and compatibility relates strains with deformation/displacements. These three sets of equations together with appropriate boundary conditions make up the mathematical aspect of the problem."

"[T]he ratio [of] radii of curvature to thickness of the shell, \frac{R}{t}... greater than 20 can be characterized as thin shells... an egg shell has a ratio of around 55..."

"[W]e will mainly be dealing with uniform shells. The shells are uniform in the sense that the material properties do not vary through the thickness. (RC) is... regarded as sufficiently uniform... [since] the difference in between steel and concrete is not large..."

"The greatest of them all, in my opinion was Nervi. ...First of all, he did a tremendous volume of work. Now Torroja, from Spain, was very good, but the bulk of his work was quite small. ...Candela came along and... was very experimental and very creative, but he stuck almost entirely with the hyperbolic paraboloid form of the shells. ...[H]e did... a lot of great buildings, but they were... limited in that they were all this one type... Nervi stuck with all kinds of different stuff: precast... and Nervi had a laboratory in ... where he made experimental models. ...Torroja had a lab too and... finally became... just a professor... [so he] didn't do a great deal of volume. ...Nervi kept on doing these things his whole life... working with models, and working with whatever theory he could learn... [T]he great Lamella roof hangar he built before the war, that the Germans finally blew up when they had to retreat from Italy, was a magnificent... and a huge structure... [T]he other two... Torroja and Candela, were excellent engineers. Candela became a friend of mine later on... but they never had the tremendous variety and the huge buildings that Nervi did... Nervi's the guy that I really admire... most..."

"The first shell I did was in Honalulu, and there I worked with an architect, that I had worked with at the Navy yard, named Pete Wimberly... Wimberly's architectural firm went on to be one of the biggest in the world. ...Pete and I were good friends, and when I went to Honolulu I'd stay in his house, and we'd start barnstorming at night. ...A lot of our stuff was just crazy talk, but a lot of it was freeing ourselves of inhibitions that later on we remembered... Pete had a very good intuitive sense for structure. He could... guess a structure that would make sense. ...[T]he first shell I did was a bowling alley near Pearl Harbor... a single curvature shell, cylindrical shapes... a span of about 93 feet... I could not find any way that... other shells were engineered. If you tried... you'd always get some kind of double-talk... [T]he world didn't have translations of everything then, like it has now. If a guy did something behind the it stayed... [T]he way I finally did it, I figured out that it must behave an awful lot like a... simple beam, even though it was a... curved structure, and so largely I figured it that way and it worked fine, and it's still up, and it was quite thin, it was 2 1/2 inches thick. In that day that was pretty daring..."

"Now what got me into shells... was a building in South America... and it absolutely enchanted me. It was in ... a baseball stadium... doubly curved... I saw this thing, and all I'd ever known... the buildings that were being built in those days were boxes, very uninspired things, and here I see this picture, this gorgeous shell... and it just enchanted me. I thought, "My God, what a beautiful structure, but how on earth does it stand up? How did the guy do it?" ..[T]hat is what really made me decide, "I've got to get the answer to this. How is this done?" [T]hat's what set me off on years and years of searching before I finally found a way to do it. ...[W]hen I finally did a building... I searched around into the theory of shells until I understood the theory... [T]hen I started looking for ways of solving these things, and I found out that they did not exist in the... architectural structural engineering profession... [F]ortunately at that time... we had here a very huge aerospace industry, and I had friends at Lockheed... I got in touch with a guy at Lockheed... and they had ways of solving very difficult problems because they were building the rockets... and so I found this way of doing it... [I]t was a very tedious, complex way of doing it, but you would get an actual, true answer... [I]t was done... the same way that it's done today with computers... But you could do it my way... You took two guys... I was one of them... they go through it step by step, and then [periodically]... compare the answer... to make sure that they don't go off. ...You could get an answer. You don't get it down to the forth of fifth decimal... The smallest I could get, chunks of the shell to work with, would be about [a theoretical] 2 feet square... Today, with a computer, you can get down to 2/10 of an inch... But it was such a tedious, horrible way of working that I never used the system again. By then I learned enough that I knew ways of short-cutting that were not as accurate... but that were close enough... [B]y this time I had developed a pretty good feel... and so I'd cut shells in pieces in my mind, put them back together again, and put them in equilibrium... From this, I finally found my way of doing things. ...As far as I know, nobody had ever done it that way... They'd done aerospace stuff this way... but there they'd put ten guys on it, not two. ...Several times I did things that I thought were the first, but I just said that "It's not universally used, or known..." or something like that. ...You're doing something that you're not really aware of yourself, which is, you're developing a very sophisticated, intuitive way of working with these things, where you can just... take them and you can say it doesn't look right... which was the way architecture was done all through the Middle Ages... in fact, in Antiquity... they didn't have engineers, all they had were architects."

"Looking back to the past century, there were various visionary designers such as Isler, Otto, Candela and Shukhov using design methods comparable to today’s computational design, operating in a pre-computational parametric set-up. They applied mathematical algorithms and principles observed in nature to develop pioneering buildings... as milestones of architectural production. Vladimir Shukhov... was one of the first to embrace such an innovative approach."

"One of Shukhov’s most significant architectural inventions was the thin metal lattice (or ' shell') structure. This was developed after intense research into the most rational type of rafters which weighed and cost the least and which could be assembled quickly. Shukhov suggested a formula to define the proportional relationships between structural elements, which at first sight seemed senseless:α = e = c'where a- length of panels, e - minimal distance between frames, and с - distance between two purlins, dependent on the actual situation"

"According to the formula, the minimal covering weight could be achieved only if the construction had no s and if the distance between es was equal to the distance between the missing purlins. The answer to this riddle was the spatial lattice structure, where trusses and purlins were the same, and the distances between trusses and purlins were equal. In 1895 Shukhov obtained a patent for the invention. The new structures were first presented to the general public at the All-Russian Industrial Art Exhibition in Nizhniy Novgorod in 1896... where Shukhov designed a number of objects using three types of lattice structure: suspension, vaulted and rigid spatial shell."

"Suspension lattice structures... were based on tension, the most advantageous type of stress for metal constructions... designed according to Shukhov’s elaborate investigations of material properties. ...They were called ‘roofs without trusses’... and the clear, extremely simple suspension structure system and the easy-to-perform node conjunction made on-site construction fast and straightforward."

"Shukhov’s lattice-suspended and vaulted structures represented a carrying surface, which could be shaped in any form. ...The density of the grid made it possible to attach it to the shell without additional structures. ...[T]he grids were two to three times lighter than roofs with conventional frames..."

"In 2010, the journal Detail published an analysis of Shukhov’s constructions, calling his approach to design 'an early example of ’..."

"Galankin... writes that Shukhov used to make calculations in a unique way... so laconic... that other specialists found them difficult to understand. In spite their brevity... if Shukhov was asked about load, rod stress, rod profile and section, rivet quantity, material weight, temperature impact or any other specifications, he always had an answer, because his concise calculations covered all these aspects, but nothing that was irrelevant..."

"Like all great churches, that are not mere store-houses of theology, Chartres expressed, besides whatever else it meant, an emotion, the deepest man ever felt,— the struggle of his own littleness to grasp the infinite. You may, if you like, figure in it a mathematic formula of infinity,— the broken arch, our finite idea of space; the spire, pointing, with its converging lines, to Unity beyond space; the sleepless, restless thrust of the vaults, telling the unsatisfied, incomplete, overstrained effort of man to rival the energy, intelligence and purpose of God. Thomas Aquinas and the schoolmen tried to put it in words, but their church is another chapter. In act, all man's work ends there;— mathematics, physics, chemistry, dynamics, optics, every sort of machinery science may invent,— to this favor come at last, as religion and philosophy did before science was born."

"...we must go to the poets to see what they all meant by it; but the sum is an emotion — clear and strong as love and much clearer than logic,— whose charm lies in its unstable balance. The Transition is the equilibrium between the Love of God,— which is Faith, and the Logic of God,— which is Reason; between the round arch and the pointed. One may not be sure which pleases most, but one need not be harsh towards people who think that the moment of balance is exquisite. The last and highest moment is seen at Chartres where, in 1200, the charm depends on the constant doubt whether emotion or science is uppermost."

"Granted a Church, Saint Thomas's Church was the most expressive that man has made, and the great gothic Cathedrals were its most complete expression. Perhaps the best proof of it is their apparent instability. Of all the elaborate symbolism which has been suggested for the gothic Cathedral, the most vital and most perfect may be that the slender nervure, the springing motion of the broken arch, the leap downwards of the flying buttress,— the visible effort to throw off a visible strain,— never let us forget that Faith alone supports it, and that, if Faith fails, Heaven is lost. The equilibrium is visibly delicate beyond the line of safety; danger lurks in every stone. The peril of the heavy tower, of the restless vault, of the vagrant buttress; the uncertainty of logic, the inequalities of the syllogism, the irregularities of the mental mirror,— all these haunting nightmares of the Church are expressed as strongly by the gothic Cathedral as though it had been the cry of human suffering, and as no emotion had ever been expressed before or is likely to find expression again. The delight of its aspirations is flung up to the sky. The pathos of its self-distrust and anguish of doubt, is buried in the earth as its last secret. You can read out of it whatever else pleases your youth and confidence; to me, this is all."

"Gaudí was drawn not just to the aesthetics of the catenary but also to what it represented mathematically. His use of catenaries made the structural mechanics of a building a principal feature of its design. Gaudí realized that the entire architecture of a building could be drafted using a model of hanging chains... when he was commissioned to design a church the Colònia Güell... he made an upside-down skeleton of the project. Instead of using metal chains, he used string weighed down by hundreds of sachets containing lead shot. The weight of each sachet on the string created a mesh of 'transformed' catenary curves. The arches of these transformed catenaries were the most stable curves to withstand a corresponding weight at the same position (such as the roof, or building materials)."

"Why do you speak to me of the stones? It is only the arch that matters to me." Polo answers: "Without stones there is no arch."

"Wherefore a monk's whole attention should thus be fixed on one point, and the rise and circle of all his thoughts be vigorously restricted to it; viz., to the recollection of God, as when a man, who is anxious to raise on high a vault of a round arch, must constantly draw a line round from its exact centre, and in accordance with the sure standard it gives discover by the laws of building all the evenness and roundness required...."

"Centres, or centre-pieces of wood, are put by builders under an arch of stone while it is in the process of construction till the key-stone is put in. Just such is the use Satan makes of pleasures to construct evil habits upon; the pleasure lasts till the habit is fully formed; but that done, the habit may stand eternal. The pleasures are sent for firewood, and the hell begins in this life."

"Within a shed erected on the construction site of the church of the Sagrada family... Gaudí... made an upside-down model using lightweight cables to represent the structural lines of the future church—a model based on the structural notion of the inverted catenary. ...Analogically represented by little pouches filled with lead pellets the action of the stresses has been done ...The resulting chain configurations are used to determine the geometrical shapes and structural profiles of columns, pillars, arches, and vaults. ...Vicens Vilarrubias i Valls took photos of the model ...Gaudí used these photos upside-down to draw over them the external and internal elevations, studies of details and sections of the building."

"The exact shape of funicular (sometimes called linear or theoretical) arch[es] that carry all applied loads by axial compression only, may be developed by the same methods as used for finding the shape of cables. ...If the actual shape of the arch is different from funicular shape, the bending moment at any section of an arch is proportional to the ordinate or intercept between the given arch and funicular arch... This principle is called Eddy's Theorem."

"Corol. 6.—In a vertical plane, but in an inverted situation, the chain will preserve its figure without falling, and therefore will constitute a very thin arch or fornix: that is, infinitely small, rigid, polished spheres, disposed in an inverted curve of a catenaria, will form an arch no part of which will be thrust outwards or inwards by other parts, but, the lowest parts remaining firm, it will support itself by means of its figure... none but the catenaria is the figure of the true and legitimate arch or fornix. And when the arches of other figures is supported, it is because in their thickness some catenaria is included. ...From Corol. 5... it may be collected, by what force an arch or buttress presses a wall outwardly, to which it is applied. For this is the same with that part of the force sustaining the chain, which draws according to a horizontal direction. For the force which in the chain draws inwards, in an arch equal to the chain drives outwards. All other circumstances, concerning the strength of walls to which arches are applied, may be geometrically determined from this theory, which are the chief things in the construction of edifices."

"From all ages architects have made use of arches in public buildings, as well for strength as beauty. Yet what was the true geometrical figure of an arch was not known before my demonstrations came out."

"It was comparatively late that the theory of arches attracted the notice of mathematicians. Dr. Hooke gave the hint, that the figure of a perfectly flexible cord or chain, suspended from two points, was the proper form for an arch. Galileo considered the catenary as a parabolic curve, and John Bernouilli appears to have been the first who discovered its nature. Dr. Gregory (Phil. Trans. 1697) published an investigation of its properties, and observes that the inverted catenary is the best form for an arch on account of its lightness. This is true so long as it is not pressed by an extraneous weight. It is not, however, capable of bearing a load on any part, much less of being filled up on the spandrels, which must be the case in practice. Other considerations must be involved before it can be fitted to receive a roadway or other weight, either upon its crown or haunches."

"The flexible chain, hanging under the action of applied force, will assume a certain shape, namely the catenary if the chain is subjected only to its own weight, or a if the load is uniformly distributed horizontally. Whatever the load, there will be a corresponding shape, and the structural action in all cases is the same; purely tensile forces are transmitted along the centre line of the chain. As Hooke saw in 1675 with his ut pendet continuum flexile, sic stabit contiguum rigidum inversum, ...a hanging chain may be inverted to give a satisfactory arch to carry the same loads, but working in compression rather than tension. The compressive arch, however, if of vanishingly small thickness, would be in unstable equilibrium, and stability is conferred in practice by making the arch ring of finite depth. Now if purely compressive forces, without bending, are to be transmitted from one portion of the arch to the next (as purely tensile forces are transmitted in the chain), then the arch centre line can accept only a single type of loading. Thus a parabolic arch can carry only a uniformly distributed horizontal load (although the magnitude of the load is arbitrary). It is the depth in a real arch which enables the arch to carry wider ranges of loading; a large number of different idealized centre-line arches can be contained within a given practical profile. ...[T]his must be so, or no mediaeval bridge would have survived its decentering."

"The true Mathematical and Mechanical Form of all manner of es for building with the true butment necessary to each of them, a Problem which no Architectonick Writer hath ever yet attempted, much less perform'd. ...Ut pendet continaum flexile, sic stabit contiguum rigidum, which is the Linea Catenaria."

"History fades into fable; fact becomes clouded with doubt and controversy; the inscription moulders from the tablet: the statue falls from the pedestal. Columns, arches, pyramids, what are they but heaps of sand; and their epitaphs, but characters written in the dust?"

"I will begin with the subject of your bridge... and it is with great pleasure that I learn... that the execution of the arch of experiment exceeds your expectations. ...You hesitate between the catenary and portion of a circle. I have lately received from Italy a treatise on the equilibrium of arches, by the Abbé Mascheroni. It appears to be a very scientifical work. I have not yet had time to engage in it; but I find that the conclusions of his demonstrations are, that every part of the catenary is in perfect equilibrium. ...I would propose that you make your middle rail an exact catenary, and the interior and exterior rails parallels to that. It is true, they will not be exact catenaries, but they will depart very little from it; much less than portions of circles will."

"He talked to her endlessly about his love of horizontals: how they, the great levels of sky and land in , meant to him the eternality of the will, just as the bowed Norman arches of the church, repeating themselves, meant the dogged leaping forward of the persistent human soul, on and on, nobody knows where; in contradiction to the perpendicular lines and to the Gothic arch, which, he said, leapt up at heaven and touched the ecstasy and lost itself in the divine."

"Like two cathedral towers these stately pines Uplift their fretted summits tipped with cones; The arch beneath them is not built with stones, Not Art but Nature traced these lovely lines, And carved this graceful arabasque of vines; No organ but the wind here sighs and moans, No sepulchre conceals a martyr's bones, No marble bishop on his tomb reclines. Enter! the pavement, carpeted with leaves, Gives back a softened echo to thy tread! Listen! the choir is singing; all the birds, In leafy galleries beneath the eaves, Are singing! listen, ere the sound be fled, And learn there may be worship without words."

"There is [a].. type of structural behaviour which is not beam-like, truss-like or frame-like but funicular. ...from the Latin for rope - funis. ...the cable is flexible and can only have internal forces of axial tension. ...a cable is not a frame ...Like any spanning structure it has to carry the overall and s. ...If a cable is loaded with a uniformly distributed load, the cable will take up a parabolic shape. ...the funicular shape for this load pattern. ...Because... cables are in direct tension, if they were turned upside down they would be in direct compression. ...this would not be possible for a cable but if the structure could carry compression then the funicular shape obtained from the hanging cable gives the correct shape for an arch that is in direct compression everywhere. ...the idea of inverting cables to find arch shapes was only stated in 1675 by ...Robert Hooke... G. Poleni in 1748 as part of his investigation into the structural behaviour of the dome at St. Peter's... used a correctly loaded chain to determine the funicular shape... If...the loading changes or the arch is built to the wrong shape and the funicular line moves outside the arch, then the arch will have to maintain its shape by frame action or collapse."

"So counsel'd he, and both together went Into the thickest wood; there soon they chose The fig-tree, not that kind for fruit renowned, But such as at this day to Indians known In Malabar or Decan spreads her arms, Branching so broad and long, that in the ground The bended twigs take root, and daughters grow About the mother tree, a pillar'd shade High overarch'd, and echoing walks between."

"Arches form a distinct class of two-dimensional structural elements that resist external loads through their profile (form). Compared to a beam element of the same span and subjected to the same load, the B.M. in an arch will be much smaller because of the negative B.M. due to the horizontal thrust at the supports (abutments). Graphical solution of arches is much simpler than the analytical solution, and is of adequate accuracy for practical purposes. The solution is based on Eddy's theorem on B.M. in arches and the concept of pressure (thrust) lines. ...In case the structure has the profile of the force polygon, the B.M. at any section will be zero... The structure, in such a case, will be subjected only to axial compression. Such a profile along the length of a beam or frame is known as the pressure line or line of thrust. ...the profile for a given system of forces, which would induce only compressive forces. The profile of a pressure line resembles an arch with linear segments; the profile is sometimes known as a linear arch."

"The Romans were the first builders in Europe, perhaps the first in the world, fully to appreciate the advantages of the arch, the vault and the dome."

"The arch is one of those brilliant innovations... Spanning... with horizontal beams is a losing game. ...By converting all the stress that fractures the middle of... stone beams—technically tension—into compression on stone piers larger... spaces could be spanned. ...But shift the pressure even slightly off center, and the pillar is likely to collapse. ...In their early incarnations, the limitations of both arch and dome was the ability of craftsmen to shape the stones carefully enough to create blocks precisely in the wedge shapes needed for a particular arch. Despite their mathematical sophistication in most other respects, the architects of antiquity lacked a proper geometric solution to the ideal form of the arch. (It was not until 1675 that the English polymath Robert Hooke described mathematically the shape of an arch loaded in pure compression, that is, with no tension, by showing how it describes an upside-down version of the catenary curve of a hanging chain.) As a result, the only way they could design an arch, and its component stones, was completely by eye, and... such tolerances commanded high prices. Rome overcame this drawback with typical ingenuity, first replacing stones and mortar... and expensive stonecutters with relatively cheap bricklayers. Even more ingeniously, some anonymous Roman builder found how to combine the mortar—in Latin pulvis puteoli—with lime, sand, and gravel to make the first concrete. ...The concrete domes of Rome were not surpassed until the age of steel."

"Certainly the most striking contemporary example of a similar form [ arch] is to be found in St. Louis' ... In its incredible scale and construction out of metal plates this structure also serves as a convenient reminder of the important developments of the production of iron and steel that took place during the Industrial Revolution and that have so significantly affected arches as well as all other types of structural forms for the past 150 years."

"French architects and engineers in the 16th, 17th, and 18th centuries occupied themselves a good deal with roofs with curved ribs, and two systems of constructing the rib were worked out. In the most modern of them, that invented by Colonel Emy, the ribs were constructed of a series of thicknesses of bent timber, one on the back of another, and held together by bolts. In the older system that of Philibert de l'Orme, the ribs were also built up, but the pieces composing them are placed side by side, and either form a polygon approaching a semicircle or are cut to bring them to a curve.&bnsp;thumb|Bourse de commerce (dome of the Paris Corn Market)In fact, the ribs are very much such as... used for the great dome of the Paris Corn Market. There is, however, a great difference between a dome—the strongest of all forms—and one permitting the introduction of as many rings of ties as may be desired; and a roof over an ordinary oblong space, where no such binding together is admissible, and where straight rafters may have to be used, which loads the rib at certain points only. In the latter case, a good many precautions have, generally speaking, to be taken to prevent the rib from being unequally loaded, and so either spreading or losing its shape in some other way. The rib made of unbent timber, side by side, on De l'Orme's plan, is admitted to be stronger than the one made of bent timbers laid one on the back of the other; but both have been largely used, and good examples of both may be met with, even if we confine ourselves to English ones alone, and leave the French ones unnoticed. thumb|Chatsworth - Great Conservatory in the 19th centuryA very fine roof with ribs, one on which the load (though light) is borne without a rafter solely by the rib, is the one erected over the great conservatory built by His Grace the Duke of Devonshire, at Chatsworth. ...It consists of a wide and lofty central portion, with a kind of broad aisle at the sides, roofed at a lower level. The central roof here is of the section of a pointed arch and hipped at both ends, and is entirely covered with glass. It is carried by timber ribs, and the glazing is on the ridge and furrow principle. The low aisle referred to forms to some extent an abutment for the ribs, and the ridge-and-furrow glazing helps, no doubt, to fortify them, but still the greater part of the strength is derived from the ribs themselves."

"All building naturally divides into two classes, the architecture of the beam and that of the arch, which have been called trabeated and arcuated—according to the means which it uses for covering openings and spaces—the first being that which covers them by beams or s, the second that which uses arches. The logical development of the two classes leads in the one to flat ceilings and straight roofs, in the other to vaults and s."

"[A]long with the order, the architecture of Rome had inherited from the Etruscans the arch, despised and rejected by the Greeks... It was probably the child of the bricklayer, who has no other means of bridging an opening; at least we find it first in alluvial Mesopotamia, where the Chaldees, who had no stone to build with, raised their great pyramids and built their palaces of bricks, and where the Assyrian conquerors who appropriated their civilization and art, as the Romans did the Greek, adopted it from them and used it on a great scale. Born in the oriental brick-fields, it came to the Greeks with all the associations of ignoble material, profane uses, and hated sponsors. Every influence of religious association, conservatism, and respect for the Egyptian example, from which they had learned much, bound them to their trabeated style. Still more, the instinct for harmony of form which dominated both Egyptians and Greeks could but warn them that the use of the arch not only implied a change of their constructive system, but was at war with their whole architectural scheme of lines, proportions, and monumental effect. Even as late as the time of , after long subjection of Greece to Roman control, the arcaded conduit to the at Athens seems to show the persistent resistance of Greek workmen on their own soil to the very principle of the arch, for the arches are cut through solid slabs of stone instead of being built up in the fashion of the true arch."

"The recognized leading position of the author in this field of structural design and the extensive use of his system of arch construction in all parts of the world should be sufficient justification for presenting this book... The present work constitutes one of the most thorough treatments of reinforced concrete arches in any language. ...After a brief discussion of the fundamental principles of arches and a simple though comprehensive treatment of the stresses in reinforced concrete sections, there are presented analytic and graphic methods for the complete design of all types of concrete arches occurring in practice. The graphic methods which are given, permitting the use of influence lines, will be found very practical... The effects of temperature, of yielding abutments and of nonvertical loads are separately considered. ...In addition to the exact treatments, simple approximations and short cuts are introduced which will prove highly useful for preliminary and less exacting designs. Easily-applied formula are developed for determining in advance the best curve for an arch and the required dimensions and reinforcement. ...The principle of the Melan system of arch construction is fully explained and its inherent economy concretely demonstrated."

"On the arch strip... we have certain forces acting; usually... forces of gravity... vertical loading. ...the dead weight of the arch and superstructure together with the useful or live load. Now consider the archstrip (Fig 1) divided into separate segments or s by joint-planes or sections 1, 2, 3, ..., with the end planes A and B resting against fixed abutments. With the... assumption of no shears in the head planes, each voussoir, e.g., 1-2, is subjected to the action of three forces, namely, the given external load P2 and the two resultant pressures R1 and R2 in the abutting joints. These forces must hold each other in equilibrium and may therefore be represented by a force triangle 1-2-O; in this way either joint-pressure may be determined when the other is known. Consequently all of the joint-pressures may be found as soon as any one of these forces is given in its magnitude, direction, and point of application. The forces acting at the end planes A and B are the pressures, and their opposing forces are the abutment reactions K1 and K2. The application of these reactions takes the place of the abutments, so that the arch may be considered an independent system in equilibrium under the forces \sum P, K1 and K2."

"The action and reaction between adjacent voussoirs occur along the lines of the forces R, therefore the polygon composed of these forces is appropriately named the Line of Resistance. It may be obtained as the funicular polygon of the forces P with the end-reactions K as the terminal sides."

"[B]uilding stones and concrete exhibit the properties of elasticity, although not so perfectly as to permit a constant ratio between stress and strain... For compression within the limits of safe stress, however, such proportionality may be assumed without any considerable error so that a constant coefficient of elasticity may be used... The theory of the elastic arch may therefore be applied to arches of all classes of masonry, including monolithic arches of concrete, provided no tensile stresses or only very small tensile stresses are allowed to occur. The same theory also forms the basis for the design of reinforced concrete arches..."

"In the summer of 1884... the Syndics... placed in my hands the manuscript of the late Dr Todhunter's History of Elasticity, in order that it might be edited and completed..."

"[I]t was not till I had advanced... into the work that I felt convinced that... the... writer's terminology and notation must be abandoned and a uniform terminology and notation adopted for the whole book... to be available for easy reference, and not merely of interest to the historical student."

"[T]he notation and terminology will be found fully discussed in Notes B—D of the Appendix, which I would ask the reader to examine before passing to the text."

"[C]onsistency in [notation and terminology] will be found after the middle of the chapter devoted to Poisson."

"The symbols and terms used in the manuscript are occasionally those of the original memoirs, occasionally those of Lamé or of Saint-Venant... the memoirs being of historical rather than scientific interest, and their language often the most characteristic part of their historical value."

"Dr Todhunter's manuscript consists of two distinct parts, the first contains a purely mathematical treatise on the theory of the 'perfect' elastic solid; the second a history of the theory of elasticity. The treatise based principally on the works of Lamé, Saint-Venant and Clebsch is yet to a great extent historical, [i.e.,] many paragraphs are composed of analyses of important memoirs."

"The changes I have made in that manuscript are of the following character; the introduction of a uniform terminology and notation, the correction of clerical and other obvious errors, the insertion of cross-references, the occasional introduction of a remark or of a footnote. The remarks are inclosed in square brackets. With this exception any article in this volume the number of which is not included in square brackets is due entirely to Dr Todhunter."

"I... regret that I have not devoted special chapters to such elasticians as Hodgkinson, [Guillaume] Wertheim and F. E. Neumann; in the latter case the regret is deepened by the recent publication of his lectures on elasticity."

"I may appear to have exceeded the duty of an editor. For all the Articles in this volume whose numbers are enclosed in square brackets I am alone responsible, as well as for the corresponding footnotes, and the Appendix with which the volume concludes."

"The principle which has guided me throughout the additions I have made has been to make the work, so far as it lay in my power, a standard work of reference for its own branch of science."

"The use of a work of this kind is twofold. It forms on the one hand the history of a peculiar phase of intellectual development, worth studying for the many side lights it throws on general human progress. On the other hand it serves as a guide to the investigator in what has been done, and what ought to be done. In this latter respect the individualism of modern science has not infrequently led to a great waste of power; the same bit of work has been repeated in different countries at different times, owing to the absence of such histories as Dr Todhunter set himself to write. ...the various Jahrbücher and Fortschritte now reduce the possibility of this repetition, but besides their frequent insufficiency they are at best but indices to the work of the last few years; an enormous amount of matter is practically stored out of sight in the Transactions and Journals of the last century and of the first half of the present century."

"It would be a great aid to science, if, at any rate, the innumerable mathematical journals could be to a great extent specialised, so that we might look to any one of them for a special class of memoir. ...the would-be researcher either wastes much time in learning the history of his subject, or else works away regardless of earlier investigators. The latter course has been singularly prevalent with even some firstclass British and French mathematicians."

"Keeping the twofold object of this work in view I have endeavoured to give it completeness (1) as a history of developement, (2) as a guide to what has been accomplished."

"Taking the first chapter of this History the author has discussed the important memoirs of James Bernoulli and some of those due to Euler. The whole early history of our subject is however so intimately connected with the names of Galilei, Hooke, Mariotte and Leibniz, that I have introduced some account of their work."

"The labours of Lagrange and Riccati also required some recognition... [of] interest, whether judged from the special standpoint of the elastician or from the wider footing of insight into the growth of human ideas."

"With a similar aim I have introduced throughout the volume a number of memoirs having purely historical value which had escaped Dr Todhunter's notice."

"I have inserted... memoirs of mathematical value, omitted [by Todhunter] apparently by pure accident. For example all the memoirs of F. E. Neumann, the second memoir of Duhamel, those of Blanchet etc. I cannot hope that the work is complete in this respect even now, but I trust that nothing of equal importance has escaped..."

"My greatest difficulty arose with regard to the rigid line which Dr Todhunter had attempted to draw between mathematical and physical memoirs. Thus while including an account of Clausius' memoir of 1849, he had omitted Weber's of 1835, yet the consideration of the former demands the inclusion of the latter..."

"There has been far too much invention of 'solvable problems' by the mathematical elastician; far too much neglect of the physical and technical problems which have been crying out for solution. Much of the ingenuity which has been spent on the ideal body of 'perfect' elasticity ideally loaded, might I believe have wrought miracles in the fields of physical and technical elasticity, where pressing practical problems remain in abundance unsolved. I have endeavoured... to abrogate this divorce between mathematical elasticity on the one hand, and physical and technical elasticity on the other. With this aim in view I have introduced the general conclusions of a considerable body of physical and technical memoirs, in the hope that by doing so I may bring the mathematician closer to the physicist and both to the practical engineer. I trust that in doing so I have rendered this History of value to a wider range of readers, and so increased the usefulness of Dr Todhunter's many years of patient historical research on the more purely mathematical side of elasticity. In this matter I have kept before me the labours of M. de Saint-Venant as a true guide to the functions of the ideal elastician."

"To the late M. Barré de Saint-Venant I am indebted for the loan of several works, for a variety of references and facts bearing on the history of elasticity, as well as for a revision..."

"My colleague, Professor A. B. W. Kennedy, has continually placed at my disposal the results not only of special experiments, but of his wide practical experience. The curves figured in the Appendix, as well as a variety of practical and technical remarks scattered throughout the volume I owe entirely to him; beyond this it is difficult for me to fitly acknowledge what I have learnt from mere contact with a mind so thoroughly imbued with the concepts of physical and technical elasticity."

"The modern theory of elasticity may be considered to have its birth in 1821, when Navier first gave the equations for the equilibrium and motion of elastic solids, but some of the problems which belong to this theory had previously been solved or discussed on special principles, and to understand the growth of our modern conceptions it is needful to investigate the work of the seventeenth and eighteenth centuries."

"Galileo Galilei['s] second dialogue of the Discorsi e Dimostrazioni matematiche, Leiden 1638... both from its contents and form is of great historical interest. It not only gave the impulse but determined the direction of all the inquiries concerning the rupture and strength of beams, with which the physicists and mathematicians for the next century principally busied themselves."

"Galilei gives 17 propositions with regard to the fracture of rods, beams and hollow cylinders. ...[H]e supposed the fibres of a strained beam to be inextensible. There are two problems... discussed... which form the starting points of many later memoirs. They are the following:"

"A beam (ABCD) being built horizontally into a wall (at AB) and strained by its own or an applied weight (E), to find the breaking force upon a section perpendicular to its axis. This problem is always associated... with Galilei's name, and we shall call it... Galilei's Problem. The 'base of fracture' being defined as the section of the beam where it is built into the wall; we have the following results :— (i) The resistances of the bases of fracture of similar prismatic beams are as the squares of their corresponding dimensions. In this case the beams are supposed loaded at the free end till the base of fracture is ruptured; the weights of the beams are neglected. (ii) Among an infinite number of homogeneous and similar beams there is only one, of which the weight is exactly in equilibrium with the resistance of the base of fracture. All others, if of a greater length will break,—if of a less length will have a superfluous resistance in their base of fracture."

"The discovery apparently of the modern conception of elasticity seems due to Robert Hooke, who in his work De potentiâ restitutiva, London 1678, states that 18 years before... he had first found out the theory of springs, but had omitted to publish it because he was anxious to obtain a patent for a particular application of it. He continues:— About three years since His Majesty was pleased to see the Experiment that made out this theory tried at White-Hall, as also my Spring Watch. About two years since I printed this Theory in an Anagram at the end of my Book of the Descriptions of s, viz. ceiiinosssttuu, id est, Ut Tensio sic vis; That is, The Power of any spring is in the same proportion with the Tension thereof."

"By 'spring' Hooke does not merely denote a spiral wire, or a bent rod of metal or wood, but any "springy body" whatever. Thus after describing his experiments he writes: From all which it is very evident that the Rule or Law of Nature in every springing body is, that the force or power thereof to restore it self to its natural position is always proportionate to the Distance or space it is removed therefrom, whether it be by rarefaction, or separation of its parts the one from the other, or by a Condensation, or crowding of those parts nearer together. Nor is it observable in these bodies only, but in all other springy bodies whatsoever, whether Metal, Wood, Stones, baked Earths, Hair, Horns, Silk, Bones, Sinews, Glass and the like. Respect being had to the particular figures of the bodies bended, and to the advantageous or disadvantageous ways of bending them."

"The modern expression of the six components of stress as linear functions of the strain components may perhaps he physically regarded as a generalised form of ."

"Mariotte seems to have been the earliest investigator who applied anything corresponding to the elasticity of Hooke to the fibres of the beam in Galilei's problem. ...[H]is Traité du mouvement des eaux, Paris 1686... shows that Galilei's theory does not accord with experience. He remarks that some of the fibres of the beam extend before rupture, while others again are compressed. He assumes however without the least attempt at proof ("on peut concevoir" [we can conceive]) that half the fibres are compressed, half extended."

"G. W. Leibniz: Demonstrationes novae de Resistentiâ solidorum. Acta Eruditorum Lipsiae July 1684. The stir created by Mariotte's experiments... seem to have brought the German philosopher into the field. He treats the subject in a rather ex cathedrâ fashion, as if his opinion would finally settle the matter. He examines the hypotheses of Galilei and Mariotte, and finding that there is always flexure before rupture, he concludes that the fibres are really extensible. Their resistance is, he states, in proportion to their extension. ...[i.e.,] he applies " Hooke's Law" to the individual fibres. As to the application of his results to special problems, he will leave that to those who have leisure for such matters. The hypothesis... is usually termed by the writers of this period the Mariotte-Leibniz theory."

"Varignon: De la Résistance des Solides en général pour tout ce qu'on peut faire d'hypothèses touchant la force ou la ténacité des Fibres des Corps à rompre; Et en particulier pour les hypothèses de Galiée & de M. Mariotte. Memoires de l'Académie, Paris 1702... considers that it is possible to state a general formula which will include the hypotheses of both Galilei and Mariotte, but... it will [in most practical cases] be necessary to assume some definite relation between the extension and resistance of the fibres. ...Varignon's method ...[is] generally adopted by later writers (although in conjunction with either Galilei's or the Mariotte-Leibniz hypothesis), we shall briefly consider it here ..."

"Let ABCNML be a beam built into a vertical wall at the section ABC, and supposed to consist of a number of parallel fibres perpendicular to the wall... and equal to AN in length. Let H' be a point on the 'base of fracture,' and H'E [which is perpendicular to AC] = y, AE= x. Then if a weight Q be attached by means of a pulley to the extremity of the beam, and be supposed to produce a uniform horizontal force over the whole section NML, \; Q = r \cdot \int ydx where r is the resistance of a fibre of unit sectional area and the integration is to extend over the whole base of fracture. Q is by later writers termed the absolute resistance and is given by the above formula. Now suppose the beam to be acted upon at its extremity by a vertical force P instead of the horizontal force Q. All the fibres in a horizontal line through H' will have equal resistance, this may be measured by a line HK drawn through H in any fixed direction where H is the point of intersection of the horizontal line through H and the central vertical BD of the base. As H moves from B to D, K will trace out a curve GK which gives the resistance of the corresponding fibres. Take moments for the equilibrium of the beam about ACP \cdot l = \iint uydxdywhere l = length of the beam DT and u = HK."

"This quantity \iint uydxdy was termed the relative resistance of the beam or the resistance of the base of fracture. ...it is necessary to know u before we can make use of it. He then proceeds to apply it to Galilei's and the Mariotte-Leibniz hypotheses."

"In Galilei's hypothesis of inextensible fibres u is supposed constant = r and the resistance of the base of fracture becomesr \int ydxdy = \frac{r}{2} \cdot \int y^2dx.On the supposition that the fibres are extensible we ought to consider their extension by finding what is now termed the neutral line or surface. Varignon however, and he is followed by later writers, assumes that the fibres in the base ACLN are not extended; and that the extension of the fibre through H' varies as DH, in other words he makes the curve GK a straight line passing through D. Hence if r' be the resistance of the fibre at B, and DB = a, the resistance of the fibre at H = r'y/a or the resistance of the base of fracture on this hypothesis becomes\frac{r'}{3a}\int y^3dxThis resistance in the case of a rectangular beam of breadth b and height a becomes on the two hypotheses\frac{ra^2b}{2} and \frac{r'a^2b}{3}...his results are practically vitiated when applying the true ( Leibniz-Mariotte) theory by his assumption of the position of the neutral surface, but in this error he is followed by so great a mathematician as Euler himself."

"The first work of genuine mathematical value on our subject is clue to James Bernoulli... Véritable hypothèse de la résistance des Solides, avec la démonstration de la Courbure des Corps qui font ressort... 12th of March 1705... begins by brief notices of what had been already done with respect to the problem by Galilei, Leibniz, and Mariotte; James Bernoulli claims for himself that he first introduced the consideration of the compression of parts of the body, whereas previous writers had paid attention to the extension alone."

"Three Lemmas which present no difficulty are given and demonstrated [by James Bernoulli]: I. Des Fibres de même matière et de même largeur, ou épaisseur, tirées ou pressées par la même force, s'étendent ou se compriment proportionellement à leurs longueurs. [Fibers of the same material and of the same width, or thickness, drawn or pressed by the same force, extend or compress proportionally to their lengths.] II. Des Fibres homogènes et de même longueur, mais de différentes largeurs ou épaisseurs, s'étendent ou se compriment également par des forces proportionelles à leurs largeurs. [Fibers homogeneous and of the same length, but of different widths or thicknesses, extend or are also compressed by forces proportional to their widths.] III. Des Fibres homogènes de même longueur et largeur, mais chargées de différens poids, ne s'étendent ni se compriment pas proportionellement à ces poids; mais l'extension ou la compression causée par le plus grand poids, est à l'extension ou à la compression causée par le plus petit, en moindre raison que ce poids—là n'est à celui—ci. [Homogeneous fibers of the same length and width, but charged with different weights, neither extend nor compress proportionally to these weights; but the extension or the compression caused by the greatest weight, is to the extension or to the compression caused by the smaller, in less reason...]"

"The fourth Lemma... may be readily understood by reference to Varignon's memoir. ...Varignon supposed the neutral surface to pass through... the so-called 'axis of equilibrium'... James Bernoulli... recognises the difficulty of determining the fibres which are neither extended nor compressed, but he comes to the conclusion that the same force applied at the extremity of the same lever will produce the same effect, whether all the fibres are extended, all compressed or part extended and part compressed about the axis of equilibrium. In other words the position of the axis of equilibrium is indifferent. This result is expressed by the fourth Lemma and is of course inadmissible."

"Saint-Venant remarks in his memoir on the Flexure of Prisms in Liouville's Journal, 1856: On s'étonne de voir, vingt ans plus tard, un grand géomètre, auteur de la première théorie des courbes élastiques, Jacques Bernoulli tout en admettant aussi les compressions et présentant même leur considération comme étant de lui commettre sous une autre forme, précisement la même méprise du simple au double que Mariotte dans l'évaluation du moment des résistances ce qui le conduit même à affirmer que la position attribuée à l'axe de rotation est tout à fait indifférente. [It is surprising to see, twenty years later, a great geometer, author of the first theory of elastic curves, Jacques Bernoulli... commit precisely the same mistake of... Mariotte in the evaluation of moment of resistance which leads him... to assert that the position attributed to the axis of rotation is entirely indifferent.]"

"Bernoulli... rejects the Mariotte-Leibniz hypothesis or the application of Hooke's law to the extension of the fibres. He introduces rather an idle argument against [it], and quotes an experiment of his own which disagrees with Hooke's Ut tensio, sic vis."

"James Bernoulli next takes a problem which he enunciates thus: "Trouver combien il faut plus de force pour rompre une poutre directement, c'est-à-dire en la tirant suivant sa longueur, que pour la rompre transversalement." [Find out how much more force is needed to break a beam directly... by pulling it along its length in order to break it transversely.] The investigation depends on the fourth Lemma, and is consequently not satisfactory."

"The method of James Bernoulli with improvements, has been substantially adopted by other writers. The English reader may consult the earlier editions of Whewell's Mechanics. Poisson says in his Traité de Mécanique... Jacques Bernoulli a déterminé, le premier, la figure de la lame élastique en équilibre, d'après des considérations que nous allons développer, . . .[Jacques Bernoulli has determined, the first, the figure of the elastic blade in equilibrium, according to considerations that we will develop...]"

"Sir Isaac Newton : Optics or a Treatise of the Reflections, Refractions and Colours of Light. 1717. ...The Query [XXXIst, termed 'Elective Attractions,'] commences by suggesting that the attractive powers of small particles of bodies may be capable of producing the great part of the phenomena of nature:—For it is well known that bodies act one upon another by the attractions of gravity, magnetism and electricity; and these instances shew the tenor and course of nature, and make it not improbable, but that there may be more attractive powers than these. For nature is very consonant and conformable to herself. ... The parts of all homogeneal hard bodies, which fully touch one another, stick together very strongly. And for explaining how this may be, some have invented hooked atoms, which is begging the question; and others tell us, that bodies are glued together by Rest: that is, by an occult quality, or rather by nothing: and others, that they stick together by conspiring motions, that is by relative Rest among themselves. I had rather infer from their cohesion, that their particles attract one another by some force, which in immediate contact is exceeding strong, at small distances performs the chemical operations above-mentioned, and reaches not far from the particles with any sensible effect."

"Newton supposes all bodies to be composed of hard particles, and these are heaped up together and scarce touch in more than a few points.And how such very hard particles, which are only laid together, and touch only in a few points can stick together, and that so firmly as they do, without the assistance of something which causes them to be attracted or pressed towards one another, is very difficult to conceive."

"After using arguments from capillarity to confirm these remarks he continues:Now the small particles of matter may cohere by the strongest attractions, and compose bigger particles of weaker virtue; and many of these may cohere and compose bigger particles, whose virtue is still weaker; and so on for divers successions, until the progression end in the biggest particles, on which the operations in chemistry, and the colours of natural bodies depend; and which by adhering, compose bodies of a sensible magnitude. If the body is compact, and bends or yields inward to pression without any sliding of its parts, it is Hard and Elastick, returning to its figure with a force rising from the mutual attractions of its parts."

"The conception of repulsive forces is then introduced [by Newton] to explain the expansion of gases.Which vast contraction and expansion seems unintelligible, by feigning the particles of air to be springy and ramous, or rolled up like hoops, or by any other means than a Repulsive power. And thus Nature will be very conformable to herself, and very simple; performing all the great motions of the heavenly bodies by the attraction of gravity, which intercedes those bodies; and almost all the small ones of their particles, by some other Attractive and Repelling powers."

"A suggestive paragraph... occurs... which is sometimes not sufficiently remembered when gravitation is spoken of as a cause :—These principles—i.e. of attraction and repulsion—I consider not as occult qualities, supposed to result from the specifick forms of things, but as general laws of Nature, by which the things themselves are formed; their truth appearing to us by phenomena, though their causes be not yet discovered."

"This seems to be Newton's only contribution to the subject of Elasticity, beyond the paragraph of the Principia on the collision of elastic bodies."

"[W]hile the mathematicians were beginning to struggle with the problems of elasticity, a number of practical experiments were being made on the flexure and rupture of beams, the results of which were of material assistance to the theorists."

"Petris van Musschenbroek: Introductio ad cohaerentiam corporum firmorum.... commences at of the author's Physicae experimentales et geometricae Dissertationes. Lugduni 1729. It was held in high repute even to the end of the 18th century. ...[The] historical preface,... has been largely drawn upon by Girard. [Van Musschenbroek] describes the various theories which have been started to explain cohesion, and rejects successively that of the pressure of the air and that of a subtle medium. ...He laughs at Bacon 's explanation of elasticity, and another metaphysical hypothesis he terms abracadabra. ...[H]e falls back... upon Newton's thirty-first Query... and would explain the matter by vires internae [internal forces]. Musschenbroek assumes... we may determine them in each case by experiment. ...The source of elasticity is a vis interna attrahens... drawn directly from Newton's Optics."

"Musschenbroek... treats of the extension (cohaerentia vel resistentia absoluta) and of the flexure (cohaerentia respectiva aut transversa) of beams, but does not seem to have considered their compression. His experiments are... on wood, with a few... on metals. ...Anything of value in his work is however reproduced by Girard."

"Musschenbroek discovered by experiment that the resistance of beams compressed by forces parallel to their length is... in the inverse ratio of the squares of their lengths; a result afterwards deduced theoretically by Euler."

"Pere Maziere: Les Loix du choc des corps à ressort parfait ou imparfait, déduites d'une explication probable de la cause physique du ressort. Paris, 1727... carried off the prize of the Acadimie Royale des Sciences... 1726. Pere Maziere, Pretre de I'Oratoire... brings out clearly the union of those theological and metaphysical tendencies of the time, which so checked the true or experimental basis of physical research. It shews us the evil as well as the good which the Cartesian ideas brought to science. It is startling to find the French Academy awarding their prize to an essay of this type, almost in the age of the Bernoullis and Euler. Finally it more than justifies Riccati' s remarks as to the absurdities of these metaphysical mathematicians. Pere Maziere finds a probable explanation of the physical cause of spring in that favorite hypothesis of a 'subtile matter' or étherée. ...Mazière ...applies the Cartesian theory of vortices to the aether ..."

"G. B. Bülfinger: De solidorum Resistentia Specimen, Commentarii Academiae Petropolitanae... is a memoir of August 1729... first published... 1735. [It] commences with a reference to the labours of Galilei, Leibniz, Wurtz, Mariotte, Varignon, James Bernoulli and Parent... [His following] sections are concerned with the breaking force on a beam when it is applied longitudinally and transversally. Galilei's and the Mariotte-Leibniz hypotheses are considered. It is shewn that the latter is the more consonant with... fact, but... is not exact because it neglects the compression (i.e. places the neutral line in the lowest horizontal fibre of the beam)."

"Bülfinger... suggests a parabolic relation of the formtension ∝ (distance from the neutral line) m, where the [exponent m] power is a constant to be determined by experiment."

"[On] the question of extension and compression of the fibres of the beam under flexure... [Bülfinger] cites the two theories... that of Mariotte, that the neutral line is the 'middle fibre' of the beam, and that of Bernoulli that its position is indifferent. He... rejects both theories, and gives... sufficient reasons... [N]ot having accepted Hooke's principle... he holds that till the laws of compression are formulated, the position of the neutral line must be found by experiment."

". ...first is a memoir entitled Verae et germanae virium elasticarum leges ex phaeiwmenis demonstratae, 1731... printed in the De Bononiensi scientiarum Academia Commentarii, 1747. ...[I]t marks the first attempt since Hooke to ascertain by experiment the laws which govern elastic bodies."

"[T]he state of physical investigation with regard to elasticity in Riccati's time... [is indicated by the] remark of Bernoulli... in the corollary to his third lemma: "Au reste, il est probable que cette courbe" (ligne de tension et de compression) "est différente de différens corps, à cause de la différente structure de leurs fibres." [Moreover, it is probable that this curve (line of tension and compression) is different for different bodies, because of the different structure of their fibers.] It struck Riccati... to consider the acoustic properties of bodies. For, he remarks, the harmonic properties of vibrating bodies are well known and must undoubtedly be connected with the elastic properties—("canoni virium elasticarum" canon elastic forces])."

"Riccati... has no clear conception of , nor does [his] theory... of acoustic experiments lead him to discover that law. In his third canon he states that the 'sounds' of a given length of stretched string are in the sub-duplicate ratios of the stretching weights. The 'sounds' are to be measured by the inverse times of oscillation. ...from this ...he deduces ...that, if u be a weight which stretches a string to length x and u receive a small increment \partial u corresponding to an increment \partial x of x, then the law of elastic force is that \frac{\partial u}{u} is proportional to \frac{\partial x}{x^2}. Hence according to Riccati we should have instead of Hooke's Law: \boldsymbol{u = Ce^{-\frac{1}{x}}}, where C is constant. For compression the law is obtained by changing the sign of x. Riccati points out that James Bernoulli's statements... do not agree with this result...He notes that the equation du/u = \pm dx/x^2 has been obtained by Taylor and Varignon for the determination of the density of an elastic fluid compressed by its own weight"

"Riccati... attempt[s]... a general explanation of the character of elasticity... in his Sistema dell' Universo [System of the Universe]... written before 1754... [and] first published in the Opere del Oonte Jacopo Riccati... 1761. [Two chapters] are respectively entitled: Delle forze elastiche and Da quali primi principi derivi la forza elastica... display... dislike... of any semi-metaphysical hypothesis introduced into physics; and desire to discover a purely dynamical theory for physical phenomena."

"[Riccatti states that] the physicists of his time had troubled themselves much with the consideration of elasticity: E si può dire, che tante sono le teste, quante le opinioni, fra cui qual sia la vera non si sa, se pure non son tutte false, e quale la più verisimile, tuttavia con calore si disputa. [And it can be said that so many are the thinkers, how many opinions, among which the true is not known, even if they are not all false, and which is the most verisimilar, nevertheless, it is hotly disputed.]"

"Riccati... sketches briefly some [current] theories... Descartes... supposed [that] elasticity to be produced by a subtle matter (aether) which penetrates the pores of bodies and keeps the particles at due distances; this aether is driven out by a compressing force and rushes in again with great energy on the removal of the compression. ...John Bernoulli... supposes the aether enclosed in cells in the elastic body and unable to escape. In this captive aether float other larger aether atoms describing orbits. When a compressing force is applied the cells become smaller, and the orbits of these atoms are restricted, hence their centrifugal force is increased; when the compressing force is removed the cells increase and the centrifugal forces diminish. Such is... how the forza viva [live force] absorbed by an elastic body can be retained for a time as forza morta [dead force]. (This theory of captive aether was at a later date adopted by Euler although in a slightly more reasonable form...)"

"Riccati gives a characteristic paragraph with regard to the English theorists:...Non ci ha fenomeno in Natura, ch' eglino non ascrivano alle favorite attrazioni, da cui derivano la durezza, la fluidità, ed altre proprietà de' composti, e spezialmente la forza elastica ... [There is no phenomenon in Nature, which is not ascribed to the favorite attractions, from which is derived hardness, fluidity, and other properties of the compounds, and especially the elastic force. ...]"

"Riccati... will not enter into these disputes [as to current hypotheses as to the nature of elasticity]... For [in] his own theory he will not call to his assistance the aether of Descartes or the attractions of Newton. ...[H]e ...seems ignorant of and quotes Gravesande [Physices elementa mathematica experimentis confirmata, 1720.] to shew that the relation of extension to force is quite unknown... curious as he elsewhere cites Hooke..."

"Riccati states la mia novella sentenza [my new sentence]... Every deformation is produced by forza viva and this force is proportional to the deformation produced. ...The forza viva spent in producing a deformation remains in the strained body in the form of forza morta; it is stored up in the compressed fibres. Riccati comes to this conclusion after asking whether the forza viva so applied could be destroyed? That... he denies, making use strangely enough of the argument from design, a metaphysical conception such as he has told us ought not to be introduced into physics!La Natura anderebbe successivamente languendo, e la materia diverrebbe col lungo girare de' secoli una massa pigra, ed informe fornita soltanto d' impenetrabilità, e d' inerzia, e spogliata passo passo di quella forza (conciossiachè in ogni tempo una notabil porzione se ne distrugge) la quale in quantità, ed in misura era stata dal sommo Facitore sin dall' origine delle cose ad essa addostata per ridurre il presente Universo ad un ben concertato Sistema. [Nature would then be languishing, and matter would become a lazy, unformed mass with the long passage of centuries, and only provided impenetrability, and inertia, and stripped step by step of that force (because at any time a notable portion destroys it) which in quantity, and to an extent had been from the supreme Authority since the origin of the things, subjected to, in order to reduce the present Universe to a well-organized System.]"

"This paragraph... unit[es] the old theologico-mathematical standpoint, with the first struggling towards the modern conception of the . It is this principle of energy which la mia novella sentenza endeavours so vaguely to express, namely that the mechanical work stored up in a state of strain, must be equivalent to the energy spent in producing that state."

"Riccati... tells us that the forza viva must be measured by the square of the velocity. The consideration of the impact of bodies is more suggestive; the forza viva existing before impact is converted at the moment into forza morta and this re-converted into forza viva partly in the motion of either body as a whole, and partly in the vibratory motion of their parts, which we perceive in the sound vibrations they give rise to in the air."

"The importance of Riccati's work lies not in his practical results, which are valueless, but in his statement of method, and his desire to replace by a dynamical theory semi-metaphysical hypotheses. ...[H]is writings remind us... of Bacon, who in like fashion failed to obtain valuable results, although he was capable of discovering a new method. Euler's return to the semi-metaphysical hypothesis... is a distinct retrogression on Riccati's attempt, which had to wait till George Green's day before it was again broached."

"Gravesande in his Physices Elementa Mathematica [Vol.1; Vol. 2], 1720, explains elasticity by Newtonian attractions and repulsions. The... chapter... entitled De legibus elasticitatis [The laws of elasticity].... is of opinion that within the limits of elasticity, the force required to produce any extension is a subject for experiment only. ...he considers elastic cords, laminae and spheres (supposed built up of laminae), and finds the deflection of the beam in Galilei's problem proportional to the weight. He makes... no attempt to discuss the elastic curve."

"The direct impulse to investigate elastic problems... came to Euler from the Bernoullis."

"Galilei's problem had determined the direction of later researches... while James Bernoulli solved the problem of the elastic curve his nephew Daniel first obtained a differential equation which really does present itself in the consideration of the transverse vibrations of a bar."

"[In an Oct. 20, 1742 letter, Daniel Bernoulli] suggests for Euler's consideration the case of a beam with clamped ends, but states that the only manner in which he has himself found a solution of this "idea generalissima elasticarum" is "per methodum isoperimetricorum." He assumes the "vis viva potentialis laminae elasticae insita" must be a minimum, and thus obtains a differential equation of the fourth order, which he has not solved, and so cannot yet shew that this "aequatio ordinaria elasticae" is general.Ew. reflectiren ein wenig darauf ob man nicht konne sine interventu vectis die curvaturam immediate ex principiis mechanicis deduciren. Sonsten exprimire ich die vim vivam potentialem laminae elasticae naturaliter rectae et incurvatae durch \int ds/R^2, sumendo elementum ds pro constante et indicando radium osculi per R. Da Niemand die methodum isoperimetricorum so weit perfectionniret als Sie, werden Sic dieses problema, quo requiritur ut \int ds/R^2 faciat minimum, gar leicht solviren. [Ew. reflect a little on whether one can not deduce the curvature of the bar directly from the principles of mechanics. In the first place I express the actual elastic laminar potential, naturally right and yet curving, by \int ds/R^2, summing the element ds per constant radius of curvature R. Since no one has perfected the isoperimetric method as much as You, So this problem, which requires that \int ds/R^2 be minimum, might be easily solved.]"

"Bernoulli writes... to Euler... Sept. 1743 [and] extends his principle of the 'vis viva potentialis laminae elasticae' to laminae of unequal elasticity, in which case \int E ds/R^2 is to be made a minimum. The... letter...in... April or May 1744... expresses his pleasure that Euler's results on the oscillations of laminae agree with his own."

"The celebrated work of Euler relating to... the Calculus of Variations appeared in 1744 under the title of Methodus inveniendi lineas curvas maximi minimive proprietate gaudentes. ...an appendix called Additamentum I. De Curvis Elasticis ...commences with a statement... shewing the theologico-metaphysical tendency... so characteristic of mathematical investigations in the 17th and 18th centuries. It was assumed that the universe was the most perfect conceivable, and hence arose the conception that its processes involved no waste, its 'action' was always the least required to effect a given purpose. ...Thus we find Maupertuis' extremely eccentric attempt at a principle of Least Action. ...[I]t is... probable that physicists have to thank this theological tendency in great part for the discovery of the modern principles of Least Action, of Least Constraint, and perhaps even of the Conservation of Energy."

"[S]tating that Daniel Bernoulli... had discovered... that the vis potentialis represented by \int ds/R^2 was a minimum for the elastic curve, Euler proceeds to discuss the inverse problem... The curve is to have a given length between two fixed points, to have given tangents at those points, and to render \int ds/R^2 a minimum... No attempt is made to shew why... By the aid of the principles of his book Euler arrives at the following equations where a, \alpha, \beta, \gamma are constants,dy = \frac{(\alpha + \beta x + \gamma x^2)}{\sqrt{a^4 - (\alpha + \beta x + \gamma x^2)^2}}from this we obtainds = \frac{a^2 dx}{\sqrt{a^4 - (\alpha + \beta x + \gamma x^2)^2}}"

"Euler gives... his investigation of the elastic curve in what he has just called an a priori manner. But this method is far inferior to that of James Bernoulli; for Euler does not attempt to estimate the forces of elasticity, but assumes that the moment of them at any point is inversely proportional to the radius of curvature: thus he... writes... an equation like... Poisson's Traite de Mecanique, Vol. I., without giving any of the reasoning by which Poisson obtains the equation."

"Euler... has hitherto considered the elasticity constant, but he will now suppose that it is variable... S, which is supposed a function of the arc s; \rho is the radius of curvature. He proceeds to find the curve which makes \int S ds/\rho^2 a minimum; and... finds for the differential equation of the required curve\alpha + \beta x -\gamma y = S/\rho where \alpha, \beta, \gamma are constants."

"Euler takes the case in which forces act at every point of the elastic curve; and he obtains an equation like the first volume of Poisson's Traiti de Mecanique."

"Euler devotes his attention to the oscillations of an elastic lamina; the investigation is some what obscure for the science of dynamics had not yet been placed on the firm foundation of : nevertheless the results obtained by Euler will be found in substantial agreement with those in Poisson's Traite de Mecanique, Vol. II."

"1757. Sur la force des colonnes, Mémoires de l'Académie de Berlin, Tom. XIII. 1759... is one of Euler's most important contributions to the theory of elasticity. The problem... is the discovery of the least force which will suffice to give any the least curvature to a column, when applied at one extremity parallel to its axis, the other extremity being fixed. Euler finds that the force must be at least = \pi^2 \cdot \frac{Ek^2}{a^2}, where a is the length of the column and Ek^2 is the 'moment of the spring' or the 'moment of stiffness of the column' (moment du ressort or moment de roideur)."

"If we consider a force F perpendicular to the axis of a beam (or lamina) so as to displace it from the position AC to AD, and \delta be the projection of D parallel to AC on a line through C perpendicular to AC, Euler finds by easy analysis D \delta = \frac{F\cdot a^3}{3\cdot Ek^2}, supposing the displacement to be small. This suggests to him a method of determining the 'moment of stiffness' Ek^2, and he makes various remarks on proposed experimental investigations. He then notes the curious distinction between forces acting parallel and perpendicular to a built-in rod at its free end; the latter, however small, produce a deflection, the former only when they exceed a certain magnitude. It is shewn that the force required to give curvature to a beam acting parallel to its axis would give it an immense deflection if acting perpendicularly."

"Euler deduces the equation for the curve assumed by the beam AC fixed but not built in at one end A and acted upon by a force P parallel to its axis. If RM be perpendicular to AC and y=RM, x = AM, he finds\frac{y}{\theta}\cdot \sqrt{\frac{P}{Ek^2}} = sin(x \sqrt{\frac{P}{Ek^2}}),where \theta = \angle RCM. Hence since y = 0, when x = a the length of the beam, a \sqrt{\frac{P}{Ek^2}} must at least = \pi, whence it follows that P must be at least = \pi^2 \cdot \frac{Ek^2}{a^2}. This paradox Euler seems unable to explain."

"If Q be the total weight of the beam the differential equationEk^2 ad^3 y + Pa (dx)^2 dy + Qx(dx)^2 dy = 0is obtained... This is reduced by a simple transformation to a special case of Riccati's equation, which is then solved on the supposition that \frac{Q}{P} is small. Euler obtains finally for the force P, for which the rod begins to bend, the expressionP = \pi^2 \cdot Ek^2/a^2 - Q \cdot (\pi^2 - 8)/2\pi^2;which shews that the minimum force is slightly reduced by taking the weight of the beam into consideration."

"Determinatio onerum quae columnae gestare valent. Examen insignis paradoxi in theoria columnarum occurrentis. De altitudine columnarum sub proprio pondere corruentium. [all in] Acta Academiae Petropolitanae [1778, 1780]. The first memoir... points out that vertical columns do not break under vertical pressure by mere crushing, but that flexure of the column will be found to precede rupture. ...[Euler] proposes to deduce a result which is now commonly in use... to find an expression connecting Ek^2 with the dimensions of the transverse section of the column. Euler finds Ek^2 = h \cdot \int x^2 ydx, where x and y... Euler appears however to treat the unaltered fibre or 'neutral line' without remark as the extreme fibre on the concave side of the section of the column made by the central plane of flexure. Thus for a column of rectangular section of dimensions b [with]in, and c perpendicular to the plane of flexure, he finds...Ek^2 = \frac{1}{3} b^3 ch, and the like method is used in the case of a circular section."

"Euler... calculate[s] the flexure which may be produced in a column by its own weight. If y be the horizontal displacement of a point on the column at a distance x from its vertex, the equation Ek^2 \cdot \frac{d^2y}{dx^2} + b^2 \int_0^y xdy = 0 is found, where the weight of unit volume of the column is unity and its section a square of side b. ...[I]f a be the altitude of the column and m = Ek^2/b^2, it is found that the least altitude for which the column will bend from its own weight is the least root of the equation,0 = \frac{1 \cdot a^3}{4! m} + \frac{1 \cdot 4 \cdot a^6}{7! m^2} - \frac{1 \cdot 4 \cdot 7 \cdot a^9}{10! m^2} + \frac{1 \cdot 4 \cdot 7 \cdot 10 \cdot a^{12}}{13! m^2} - \mathrm{etc.}Euler finds that this equation has no real root, and thus arrives at the paradoxical result, that however high a column may be it cannot be ruptured by its own weight. <!--(77-78.)p.45"

"P. S. Girard. Traite Analytique de la Resistance des solides, et des solides d'e'gale Resistance, Auquel on a joint une suite de nouvelles Experiences sur la force, et Velasticite specifique des Bois de Chine et de Sapin. Paris, 1798. ...This work very fitly closes the labours of the 18th century. It is the first practical treatise on Elasticity; and one of the first attempts to make searching experiments on the elastic properties of beams. It is not only valuable as containing the total knowledge of that day on the subject, but also by reason of an admirable historical introduction... The work appears to have been begun in 1787 and portions of it presented to the Academie in 1792. Its final publication was delayed till the experiments on elastic bodies, the results of which are here tabulated, were concluded at Havre. ...We are... considering the period of the French Revolution."

"The book... introduction is occupied with an historical retrospect of the work already accomplished in the field of elasticity... [and] concludes with an analysis of Girard's own work."

"The first section of Girard's treatise is concerned with the resistance of solids according to the hypotheses of Galilei, Leibniz and Mariotte. He notes Bernoulli's objections to the Mariotte-Leibniz theory; but remarks that physicists and geometricians have accepted this theory... [H]e thinks it probable that Galilei's hypothesis of non-extension of the fibres may hold for some bodies—stones and minerals—while the Mariotte-Leibniz theory is true for sinews, wood and all vegetable matters (cf. p. 6). As to Bernoulli's doubt with regard to the position of the neutral surface, Girard accepts Bernoulli's statement that the position of the axis of equilibrium is indifferent, and supposes accordingly that all the fibres extend themselves about the axis AC..."

"[Girard's] book forms... a most characteristic picture of the state of mathematical knowledge on the subject of elasticity at the time and marks the arrival of an epoch when science was to free itself from the tendency to introduce theologico-metaphysical theory in the place of the physical axiom deduced from the results of organised experience."

"General summary. As the general result of the work... previous to 1800... while a considerable number of particular problems had been solved by means of hypotheses more or less adapted to the individual case, there had as yet been no attempt to form general equations for the motion or equilibrium of an elastic solid. Of these problems the consideration of the elastic lamina by James Bernoulli, of the vibrating rod by Daniel Bernoulli and Euler, and of the equilibrium of springs and columns by Lagrange and Euler are the most important. The problem of a vibrating plate had been attempted, but with results which cannot be considered satisfactory."

"A semi-metaphysical hypothesis as to the nature of Elasticity was started by Descartes and extended by John Bernoulli and Euler. It is extremely unsatisfactory, but the attempt to found a valid dynamical theory by did not lead to any more definite results."

"In the appendix Mr. Pearson has carefully analysed the conflicting notations of different writers, and proposed a very convenient terminology and notation, which would save great trouble if universally adopted. He has also given an account of experiments carried out by Prof. Kennedy in his mechanical laboratory, which have an important bearing on the limitations of the truth of Hooke's law, or in the language of elasticity, the constancy of the ratio of stress to corresponding strain. The present volume is an indispensable hand-book of reference for the mathematician and the engineer, and in the editing and printing must be considered a very fitting tribute to the wonderful industry and application of its projector, the late Dr. Todhunter."

"At Mr Webb's suggestion, the exposition of the theory is preceded by an historical sketch of its origin and development. Anything like an exhaustive history has been rendered unnecessary by the work of the late Dr Todhunter as edited by Prof. Karl Pearson, but it is hoped that the brief account given will at once facilitate the comprehension of the theory and add to its interest."

"Mining is a uniquely political enterprise. It requires permits and capital, as well as legal and moral defenses strong enough to withstand inevitable litigation."

"Bad ventilation, deep excavation, defective supports, etc., etc., annually bring death to thousands of miners, but this system of operation saves expenses, therefore augments the gains, and gives the mine owners no occasion to be sorry. Neither does the factory-pasha care how many of "his" laborers are torn and rent apart by machinery, poisoned by chemicals, or slowly suffocated by dirt and dust. Profit is the main thing."

"All minerals are limited and especially limited at an affordable rate. Since a techno-industrial civilisation needs minerals, any such civilisation is bound to reach a point where it can’t continue."

"My invention shows a new product which helps to replace timber where it is endangered by wetness, as in wood flooring, water containers, plant pots, etc. The new substance consists of a metal net of wire or sticks which are connected or formed like a flexible woven mat. I give this net a form which looks in the best possible way, similar to the articles I want to create. Then I put in hydraulic cement or similar bitumen tar or mix, to fill up the joints."

"[W]elded wire reinforcement (WWR) [was] formerly known as welded wire mesh or fabric. Welded steel wire reinforcement is the predominant form... A grid of orthogonal longitudinal and transverse cold-drawn steel wires is welded together at every wire intersection... The size and spacing of the wires can vary... based on the requirements... Welded wire reinforcement can be epoxy coated or zinc coated (galvanized). ...Plain and deformed welded wire reinforcement is covered in... ASTM A1064... Stainless steel wires are specified according to ASTM A1022... Epoxy-coated WWR... in accordance with ASTM A884... Galvanized WWR... with ASTM A1060... Even plain wire used in welded wire reinforcement has both chemical bond and mechanical bond to the concrete. The mechanical bond results from bearing of the welded cross wires against the concrete in the grid of reinforcement."

"A thin shell is a special kind of vault whose geometry may include many shapes. ...a three-dimensional form made thicker than a membrane, so that it can not only resist tension as membranes do, but also compression. On the other hand, a thin shell is made thinner than a slab, which makes it unable to resist bending, as a slab does. In short, thin shells are structures thicker than membranes, but thinner than slabs. Thin shells are made possible by the use of materials that work well under tension and compression. Masonry has no tensile strength... Only the availability of and made a thin shell possible."

"RECOMMENDATION 6: Ferrocement in Disaster Relief. After fires, floods, droughts, and earthquakes... [t]ransportation is often disrupted... Supplies of bulky conventional building materials may be stranded outside the disaster area, whereas the basic ingredients of ferrocement may be available on the site or easily transported. The versatility of ferrocement also reduces logistical supply problems: wire mesh, cement, sand, and water can be substituted for the metal used for roofing, woods or plastic for shelters and clinics, asphalt for helipads, steel for bridges, and so on. Moreover, most ferrocement structures, though built for an emergency, will last long after the emergency is over. ...[F]errocement could be used at a disaster site for many purposes: Transport facilities, from simple boats to barges, docks, marinas, helipads, and simple floating bridges or short footbridges as well as road repairs. ...Food-storage facilities, quickly designed to local needs and quickly built, to preserve emergency food supplies. ...Emergency shelters such as, for example, the quonset type of roof, which is easy to erect and highly efficient. ..Public health facilities, such as latrines and clinics, built with ferrocement roofs and stucco-type walls of the same wire mesh and mortar. ...[C]adres of ferrocement workers could be trained in emergency applications and the supervision of local laborers at the disaster site."

"[Ferrocement defined:] A thin walled construction, consisting of rich cement mortar with uniformly distributed and closely spaced layers of continuous and relatively small diameter mesh (metallic or other suitable material)."

"The construction method chosen was the inverted wooden mold. For hulls up to 50 feet in length, and for utilizing unskilled labor, this method has been shown to be most efficient. ...The shape and fairness of the hull is first established and checked with the quick and easy-to-build wooden mold. ..The use of air-powered staple guns to fasten mesh and rods to the hull mold is a quick and efficient method and can be performed with unskilled labor. ..Lamination of the concrete skin is eliminated as the mortar is applied from one side only and vibrated through the hull shell reinforcing. ...Sagging of large unsupported areas is avoided. The men work from the outside of the hull and downwards."

"One inch (25 mm), 21 gauge, hexagonal galvanized mesh was used. This mesh was the type manufacturers describe as "reverse twist," galvanized after weaving. Ten layers were applied... Four layers of mesh were stapled to the mold over 4-mil plastic sheathing. Two more layers of mesh were stapled over 1/4-inch (6.4 mm) diameter vertical reinforcing bars which had been stapled on at 6-inch (152 mm) centers. 1/4-inch (6.4 mm) diameter reinforcing bars were then stapled longitudinally over this second layer of mesh. This layer of reinforcing bar was spot-welded to the first layer at approximately every second joint. This second layer of horizontal rods was applied on 3-inch (76 mm) centers. The last four layers of mesh were hogring fastened to the outside of this last layer of rods."

"Clear plastic 4-millimeter sheathing was hand-stapled to the mold for two reasons: ...To stop the moist mortar from falling through the joints and gaps between the wooden battens planking the mold. ...To form a barrier between the wooden mold and the fresh mortar. If no barrier were placed the wood would draw moisture from the new mortar and reduce its final strength."

"The first four layers of mesh were stapled to the mold over the plastic sheeting. Each length of mesh, already folded double, formed two layers. This first layer of mesh strips, 1-1/2 feet (457 mm) wide, was butted together. The second layer of mesh strips was laid out so as to cover the joints where the first layer was butted together, making a total of four layers of mesh."

"The vertical rods were stapled firmly to the hull. An air-powered staple gun was used..."

"Two more layers of mesh were stapled over the mold. Again 1" x 2" (25.4 mm x 51 mm) wide staples were used. The folded mesh was not lapped but just butted."

"The horizontal rods were welded on. Where a rod terminated on the hull it was lapped for six inches (152.4 mm) with another rod and spotwelded. All the rod joints were treated in this same way. The rods were stapled at approximately three-inch (76 mm) centers. Every second intersection of horizontal with vertical rods was spot welded. As there were two layers of mesh between the vertical and horizontal rods, the mesh was faired smooth in this small area. Care was taken not to burn too large a hole in the plastic sheeting where the rod welding took place."

"Wooden plugs of the same diameter as each through-hull fitting were cut out and placed on the mold in the exact position where the future through-hull fitting was to be installed later. These were cut from doweling and made one inch (25.4 mm) deep. A hole was drilled in the center of the doweling to ensure that the plug did not split when nailed to the mold. The mesh was cut away under the plug and trimmed neatly at the edges. Some attempt was made to place the doweling in a position clear of the intersecting rods."

"Starter rods for the stem, webs, bulkheads, bilge stringers, and engine beds were welded in place. These starter rods were placed at approximately six-inch (152 mm) centers. They were six inches (152 mm) long where they extended through the hull. Quarter-inch (6.4 mm) holes were drilled for these... The starter rods were lap-welded to either the vertical rods or the horizontals, depending on their position."

"One-inch (25.4 mm) chain links were welded to the hull reinforcing cage where scuppers were to be placed. These links were aligned and welded in at deck level. ...[E]xposed steel pieces such as scuppers or screeds which require welding... should always be cleaned and protectively coated."

"The last four layers of mesh were stapled to the hull mold. They were laid in the same way as the first layers. The mesh was fastened... as smoothly and as tightly as possible. It was clipped onto the horizontal rods with 3/4-inch (19 mm) hog rings. ...One-half inch (12.7 mm) hog ring staples which do a neater job could not be located ...All edges of the mesh were stapled down tightly so that no stray ends of mesh would penetrate later through the fresh mortar and thus interfere with the plasterers' work... Mesh over the chain link scuppers was clipped away and the ends fastened down neatly."

"The mortar used for the hulls was a mixture of clean, graded silica sand, ...Portland Cement Type II, and drinking-type water. This silica sand, of the grading and particle shape used in high-strength structures... The sand content used was... one 50-pound (22 Kg) bag of coarse grade, one 100-pound (44 Kg) bag of medium grade and one 50-pound (22 Kg) bag of fine grade. To this graded sand was added two 80-pound (31 Kg) bags of Portland Cement Type II and just sufficient water to make the mortar workable into the hull mesh reinforcing. ...There was one plasterer for roughly every 100 square feet (9 m2) ...Retarders or additives were not used. The sun shelters were moved into place ..."

"First a heavy coat was applied all over the hull. Men stationed inside the hull mold began systematically vibrating the mold planking and checking the gaps between the planking for mortar penetration. Once the mortar had all been applied to the satisfaction of the men vibrating and checking, the excess mortar was then scraped back to the mesh. ...A new thin coat was troweled over the hull and allowed to start setting. When it started to set the hull was sponge troweled, the sponge trowel being used in a circular motion to smooth out surface irregularities. As soon as the sponge troweling was finished, the final steel troweling began. This was carried on until the hull surface had set up too hard to be worked on any further, and was as smooth and fair as the plasterers could make it."

"The hulls were steam cured for 24 hours at a temperature of 150°F (66° C). A steam pipe, perforated for its entire length, was placed under the inverted hull and a rubberized canvas steam tent drawn completely over. The temperature was carefully brought up to 150°F (66°C) in a period of four hours. Twenty-four hours were then maintained at this prescribed temperature until, finally, it was allowed to drop slowly to ambient temperature of 85° F (30°C)."

"The hull was left untouched for 18 hours after the plaster finishing work had ceased. This allowed the hull to set-up hard enough for the men to drag the steam tent over it. It is not advisable to start steam curing too soon, as the jets of hot water from the steam pipe may wash some of the mortar off the hull while it is still green. Before steam curing began the wooden screeds were removed from around the hull sheer."

"[These] low cost, easily built, high quality ferrocement roofings... offer an innovative solution to the serious dwelling problem affecting large numbers of people, especially in the marginal urban areas and rural zones of developing countries..."

"Ferrocement was chosen as the material for the proposed roofing because of its physical properties (strength in compression and tension, impact, permeability, etc.) and because it is cheap and easy to build."

"[I]t was decided to develop a type of roofing based on prefabricated sections. ...With the partial results obtained in this stage, another part of the study could be initiated, i.e. to build this same type of element "in situ"... thus providing solutions for situations in which prefabrication is not appropriate..."

"The adaption of ferrocement precast roofings in self-help construction projects... permits the use of standard components which are easily erected without sophisticated equipment."

"The construction of the mold simply consists of making a dome of well compacted earth, covered by a layer of well-finished concrete having a thickness of 8 cm [3.15 inches], with the shape defined by the trusses... used to [shape] the mold."

"The reinforcement consists of two no. 2 bars along the edges, one of them straight and the other one with the necessary bends to provide the handles to lift and fix the dome to the structure. ...[T]wo layers of galvanized chicken wire, guage 22 with a separation of 13 mm are attached to the bars and directly mounted over the mold, one perpendicular to the other. ...[E]nsure a minimum overlap of 5 cm... and... ensure that these are stretched... to achieve the thinnest section possible."

"The mortar used for the mix is made (using a mixture) of normal or ic cement and sand in a proportion of 1:1.5 by volume and with a water-cement ratio of 0.55."

"After a couple of hours, the desired finish is applied (polishing or brushing), with the object of sealing the cracks or faults that may appear on the surface of the dome."

"The curing of the shell is achieved by covering the surface with wet sand for a period of 72 hours."

"An alternative construction method was also developed which did not require the use of any type of mold or form."

"The best solution found was to form a double curvature surface... The curvature does not necessarily follow a pre-determined law, so that it may be checked roughly "with the naked eye"."

"[T]he smaller the thickness of the cover, the better will be its quality, which is why at the time of pouring, the meshes of the wire should be well stretched. Care should be taken that only enough mortar to cover the reinforcement is used."

"One worker on one of the supports... either manually or with a trowel distributes the mortar over the chicken wire... Simultaneously, another worker from within the room... holds the mortar which is applied from the outside with a metal float or trowel in order that the mortar does not fall. Once this operation is completed, the required finish is applied both from the outside and the inside."

"The central part remains [bare wire] and will be completed after 72 hours. ...[T]he worker can [then] climb on the previously cast portion, carrying out the same process ...[S]upport the dome until the mortar has cured in order to avoid deformations caused by the weight of the mortar and to guarantee curvature of the shell."

"As eight of the shells tested failed as a result of the failure of the supporting concrete ties on the walls, it was decided to build samples which were very well reinforced... The ultimate load increased by 1.7 times for these shells..."

"The domes were very easily repaired by replacing the damaged mortar or mesh..."

"[T]he ferrocement roofings are practically waterproof and that they do not need any special treatment."

"[T]o increase the load capacity of the domes and to avoid excessive deformations, it is necessary to provide the best possible anchoring at the edges."

"[A] dome of any shape will amply comply with safety requirements. Because of this it is believed that it is possible to build domes in situ without specifying the shape of the dome, which makes skilled labor unnecessary."

"Chicken wire mesh was recommended because of its ductility. It shows no oxidation problems as it is made with galvanized wire. It has reliable properties and is low in cost."

"The purpose of this book is to match an existing resource with an existing need. The need is shelter... simpler structures... that can be assembled quickly in the wake of a hurricane or flood... that can be built economically in undeveloped countries... that... provides pleasure in the form of self-made personal retreats..."

"This highly specialized, but by no means highly complicated building technique had been almost forgotten after its first use... in the middle of the nineteenth century until it was virtually reinvented in the 1940s by... ."

"Ferrocement is used relatively little in the housing field because it is regarded as a labor-intensive... building technique. ...It is true that considerable labor is required to put together... sand, cement, and wire mesh... However, the elaborate temporary framework which consumes most of the labor in conventional work is often entirely eliminated... Even if we concede that ferrocement is impractical where labor is expensive... its use requires only time, not skill..."

"All ferrocement can be said to be , but all types of reinforced concrete are not ferrocement."

"[F]erroconcrete would be a more accurate term for our material, but that term is already in common use to describe... reinforced concrete work."

"[F]errocement ...uses wire mesh, rather than heavy rods or bars, as the primary part of its metal reinforcement and which uses sand [in a mortar mixture] rather than a mixture of sand and stone ...as the aggregate in its concrete mix. ...The resultant product can be a shell of surprising thinness, durability, resilience, and, when properly shaped, strength."

"The structural effectiveness of any reinforced concrete, including ferrocement, depends on the almost miraculously fortuitous fact (first discovered in 1870 by ) that steel and concrete have close to identical coefficients of expansion, swelling at exactly the same rate when heated, shrinking at exactly the same rate when cooled. Thus they may be permanently bonded together as a single material, utilizing the best structural characteristics of each: steel has the tensile strength... while concrete has the ..."

"Ferrocement... often acts more like steel than like a standard reinforced concrete. Hit with a hammer, it rings like a bell."

"[F]errocement... may eliminate the need for separate layers of waterproofing."

"[A]t the new ... [the] famous sail-shaped roofs (built of conventional reinforced concrete) have been covered with tile-surfaced panels of ferrocement which serve as waterproofing..."

"[B]ecause of its intrinsic hardening process which continues indefinitely, good concrete gets better and better, imperfect concrete (with flaws that invite erosion and corrosion) gets worse and worse."

"[B]efore... crude beginnings of work with conventional reinforced concrete, work with ferrocement had already begun. ...The ferrocement technique seems to have been first used by ... and, apparently... independently, by ...Jean-Louis Lambot. ...Lambot called his invention "ferciment" and used it to build boats... He constructed his first boat in 1848..."

"Although... two of the first patents for reinforced concrete of any type... were for ferrocement, that particular type of reinforced concrete was generally underutilized—in fact, forgotten—until 's work of the 1940s. ...The turning to ferrocement... was based on the logical use of a known fact: the structural behavior of reinforced concrete is most effective near the points of its reinforcement. ...Nervi was first to ask the question... why not distribute the metal reinforcement so evenly that all the concrete is in immediate proximity to it? On this theoretical foundation Nervi performed the experiments which led to his establishment of ferrocement building technique as we know it today."

"[B]y the end of 1943 Nervi's firm was at work on three 150-ton transport boats, their hulls completely of ferrocement, and one 400-ton vessel, largely of ferrocement. The first construction was interrupted by the war, and it was not until 1945 that Nervi's method resulted in... [t]he Irene... a motor boat with a 165-ton displacement. On a supporting frame of 1/4" steel rods spaced about 4" apart, Nervi spread eight layers of wire mesh, four on each side of the rods, which were tied tightly together and plastered by hand with a rich cement mortar. The resultant ferrocement was 1 3/8" thick (about the same thickness as Lambot's boat). Other than the rods sandwiched into the mesh, no formwork was needed."

"In 1947 [Nervi] built his first ferrocement structure on land, a storage warehouse... 35' x 70' and all four... walls [and] roof were of ferrocement 1 3/16" thick, their thinness made structurally feasible by their corrugated shapes."

"The following year Nervi designed and built a 41' ... the Nennele... the hull's total thickness was less than 1/2"."

"Nervi's first used of ferrocement in an important public structure was in the 1948 Exposition Hall in Turin. ...The great corrugated roof is... ferrocement panels 1 1/2" thick tied together by ribs of conventional poured concrete..."

"In the 1953 Milan Fair building and in the 1959 Flaminio stadium... Nervi used ferrocement corrugations... in strikingly cantilered roofs. A further use by Nervi of the material has been in... smooth, lightweight forms into which conventional poured concrete could be molded..."

"Most of the more recent use of ferrocement have been by others, but it is to the insight and pioneering work of that they owe their successes."

"Ferrocement is a form of reinforced concrete... [utilizing] closely spaced multiple layers of mesh or fine rods completely embedded in cement mortar. It can be formed into thin panels or sections, mostly less than 1 in. (25 mm) thick... Unlike conventional concrete, ferrocement reinforcement can be assembled into its final desired shape and the mortar... plastered directly in place without the use of a form."

"[T]he early work of Lambot... was one of the first applications of , but [was] also... a form of . His patent on wire-reinforced boats that was issued in 1847... This was the birth of reinforced concrete, but subsequent development differed from Lambot’s concept. The technology of the period could not accommodate the time and effort needed to make mesh of thousands of wires. Instead, large rods were used to make what is now called conventional reinforced concrete, and the concept of ferrocement was almost forgotten for 100 years."

"Portland cement is generally used, sometimes blended with a . The filler... is usually a well-graded sand capable of passing a 2.36 mm (No. 8) sieve. However, depending upon the... reinforcing material (mesh opening, distribution, etc.), a mortar containing some small-size gravel may be used. ...Addition of short and discrete fibers of different types favorably affects the control of cracking and the capacity... to resist tensile loads. ...[R]elatively short and slender (l/d = 100) steel fibers may be randomly distributed in hydraulic cement mortars... the overall effect being to increase tensile strength and improve the shear resistance..."

"“There’s a dream that in the future, we’ll be sitting in our home and hit a button to print our prosthetics from scratch,” Sadler says. “That might be a further out vision.” But some people think we’re already there. Sadler agrees with Kuniholn about the difficulty of attaching printed prosthetics, saying, “The fitting is a whole other black art. 3-D printing only gets you part of the way.” Of course, that’s for high-end prosthetics, the kind you hope to have. In some parts of the world, the choice is between having a mediocrely-fitting prosthetic and not having one at all. This is the situation that spurred Summit to action, as well as Patrice Johnson, who, according to Sadler, is, “the only person to have successfully designed and sold [a] functional upper limb prosthesis that used 3-D printing.”"

"“Right on the border of Burma and Thailand, there are landmines like you wouldn’t believe,” he says. These landmines leave many residents as amputees, residents who “would typically never see a prosthesis because of [the] fitting and time it would take.” Armed with Physionetics’ technology and good will, Johnson went to Burma and fitted two amputees with the printed arms. “We donated them,” he says. “All I had to do is go out there, show them how it was fit, and within an hour and a half, we had them on these two guys.” Stories like this are what drive Summit to continue his quest for a “self-use viral app for developing countries” that can create prosthetics. “There will simply never be enough prosthetists to meet their needs.” This isn’t his dream for the future; he thinks it’s a scientific possibility now. And he strongly disagrees that the materials 3-D printing can handle aren’t strong enough to work as limbs. He points out that, “the [human] bones that we have are not as strong as titanium,” a material used in many prosthetic limbs. “When you have great flexibility of geometry, as we do with 3-D printing, you can overcome what strength you don’t have,” Summit says. He says he’s found a way to overcome this strength barrier by creating a hollow prosthetic, then filling it with a lattice structure, similar to the construction of a bird’s bone. “Nature’s been doing this for a long time,” he says."

"An effective prosthesis delivers renewed functionality and is cosmetically pleasing, but it also serves to complete the wearer’s sense of wholeness. A prosthesis then, is as much medical device as it is an emotional comfort, and so the history of prosthetics is not only a scientific history, but the story of human beings since the dawn of civilization who by birth, wound, or accident were left with something missing."

"The earliest example of a prosthesis ever discovered is not a leg, arm, or even a fake eye, it’s a toe. A big toe, belonging to a noblewoman, was found in Egypt and dated to between 950-710 B.C.E. We all know that toes are important, but it’s interesting that our earliest physical example of the history of prosthetics is a toe and not something that might seem more important, like a leg or an arm."

"Stories of lives devastated by conflict or disease are all too common across low-income countries. Lack of an arm or leg can be tough anywhere, but for people in poorer parts of the planet, with so much less support and more rickety infrastructure, it is especially challenging. Some are victims of conflict, others were born with congenitall conditions. Many more are injured on roads, the casualty toll soaring in low-income nations even as it plummets in wealthier ones. Every minute, 20 people are seriously injured worldwide in road crashes. In Kenya, half the patients on surgical wards have road injuries. The World Health Organization (WHO) estimates there are about 30 million people like Nhial and Lam who require prosthetic limbs, braces, or other mobility devices. These can be simple to make and inexpensive. As one veteran prosthetist told me, his specialism is among the most instantly gratifying areas of medicine. “A patient comes in on Monday on crutches that leave them unable to carry anything. By Wednesday they are walking on a new leg and on Friday they leave with their life transformed.” Yet more than eight in 10 of those people needing mobility devices do not have them. They take a lot of work and expertise to produce and fit, and the WHO says there is a shortage of 40,000 trained prosthetists in poorer countries. There is also the time and cost to patients, who may have to travel long distances for treatment that can take five days—to assess need, produce a prosthesis and fit it to the residual limb. The result is that unglamorous items such as braces and artificial limbs are among the most-needed devices to assist lives. Yet, as in so many other areas, technology may be hurtling to the rescue, this time in the shape of 3-D printing."

"Yet for all the agonies and difficulties associated with arm loss, the bigger problem in low-income countries is when lower limb disability leads to loss of mobility. Wheelchairs are expensive and can be difficult to use when roads are pot-holed, streets are muddy and pavements are non-existent. Without a prosthetic limb, people struggle to fetch water, to prepare food and, above all, to work. This throws them back on their families and communities, intensifying any hardship and poverty."

"“If you wear a prosthesis you are disabled for about ten minutes in the morning while you have a shower, then you put your leg on and go to work. If you do not have one, then your hands are out of use with crutches so you can’t even take drinks to the table,” said Carson Harte, a 59-year-old prosthetist and chief executive of Exceed. “Without a prosthesis there are no expectations. You just go back and rely on the goodwill of your family.”"

"Traditionally, a prosthetist would wrap a stump with plaster of Paris bandages to make a reverse mold and let it dry, then fill it with more plaster that must harden. From this a socket can be forged that fits, with more modifications for precision, to the bone on the stump. Great care must be taken to avoid nerves and tender areas that are not tolerant of pressure. The key for the technician is to understand the pathology of a stump, which differs for each person. This is a cumbersome process that can take a week, especially with gait training for new patients that lasts three days. It can also be messy work, mixing up and molding the plaster, while a prosthetist visiting a rural area must cart around 20-kilo packs of plaster. But with a 3-D scanner, a digital image can be made in half an hour and sent by email, and there is no mess."

"For Wright, the prosthetic had to have a purpose. She wasn’t interested in something that made her look “normal” if it wasn’t going to help her actually do anything better. And she isn’t alone. More and more amputees, engineers, and prospective cyborgs are rejecting the idea that the “average” human body is a necessary blueprint for their devices. “We have this strong picture of us as human beings with two legs, two hands, and one head in the middle,” says Stefan Greiner, the founder of Cyborgs eV, a Berlin-based group of body hackers. “But there’s actually no reason that the human body has to look like as it has looked like for thousands of years.” Greiner himself has magnetic implants in his fingers and an RFID chip in his skin. “We actually already live in a cyborg society,” he said."

"For a long time the history of prosthetics has been inextricably linked with the history of war, and thus of men. After World War II, when soldiers were returning from the battlefield, there was a collective anxiety about whether they’d be able to re-enter their families and workplaces. Many people wanted soldiers to come back, and for everything to go back to normal. But an amputation was a physical reminder that things were not the same. “Physicians, therapists, psychologists, and ordinary citizens alike often regarded veterans as men whose recent amputation was physical proof of emasculation or general incompetence, or else a kind of monstrous de-familiarization of the 'normal' male body,” writes the professor David Serlin in the book Artificial Parts, Practical Lives. Serlin describes the ways in which the media and the military talked about these soldiers, pushing for them to be seen as “normal” in the eyes of the public. In 1946, the comic Gasoline Alley featured a man named Bix whose prosthetic lets him be a “normal American guy.” The comic shows Bix stocking shelves, and features a very surprised boss who exclaims, “I didn’t expect he’d be perfectly normal”—before hiring the man on the spot. Professional photographs taken at Walter Reed Army hospital depicted men with prosthetic devices doing “normal” male activities like lighting a cigarette and reading the sports page, their prosthetic legs adorned with “tattoos” of pinup girls."

"In a 2013 interview with The New York Times, De Oliveira Barata described her work on prosthetics as outside of engineering or medicine—the industries with which artificial limb-making are typically associated. “Making an alternative limb is like entering a child’s imagination and playing with their alter ego,” she said. “You’re trying to find the essence of the person.” She works with clients to figure out how they want to look. “It’s their choice of how to complete their body—whether that means having a realistic match or something from an unexplored imagination,” she told The Times. These sculptures aren’t accessible to everyone. Wright says she would love a custom leg, but it’s out of reach for her. “I’ve inquired about getting one,” she told me, “but it’s very ex-pensive! Crazy expensive.” Depending on what the limbs are made of, they can cost anywhere from $4,600 to $21,000. But even if not every amputee gets or wants a spike leg or a feathery suit of armor or even the curved cheetah leg, the fact that people see these alternative bodies out in the world seems to have helped push a cultural shift in how people think about normalcy. That is, at least, in Western nations. In many countries, the stigma against disability and amputation remains. In the United States, Mullins says that today’s kids don’t question her normalcy the way her peers once did, they don’t see her as disabled at all. “They see a rebuilt body as something powerful. If I’m walking around in carbon fiber or titanium or bionics, standing on a street corner, and some little kid is walking by, they presume power. They want to know if I can fly, how fast I can run.”"

"The earliest known prosthesis, dating possibly as far back as 950 B.C., was discovered in Cairo on the mummified body of an ancient Egyptian noblewoman. The prosthesis is made largely of wood, molded and stained, its components bound together with leather thread. It is, as prostheses go, tiny. Because it is a toe. The prosthetic digit—the oldest little piggy in the world—is extraordinarily lifelike, its curved nail sunken into a similarly curved bed. Which is, in its way, remarkable. A toe! One that is several thousand years old! And it's not just a toe-sized peg—a little device that would have made mobility more manageable for someone who was, by reasons of birth or amputation, missing her big toe. The prosthesis is, as much as it possibly could be, humanoid: maximally lifelike and maximally toe-like. The "Cairo Toe," as it's been dubbed, is prosthetic and cosmetic at once—evidence not just of ancient manufacturing stepping in where biology was limited, but of manufacturing engaging in an ancient form of biomimcry. Compare the Cairo Toe to today's prostheses, many of which—especially those that dominate the public imagination—seem to be inspired less by "man," and more by the Bionic Man. The blades. The hooks. The exoskeletons. This week alone has brought news of a roboticized prosthetic hand that, possibly inspired by the workings of the claw crane, foregoes five fingers for three. It has brought news of a woman who created her own prosthetic leg ... out of LEGOs. Those stories come as part of a flood of coverage of the next generation of prostheses, in which technologies from adjacent fields—3D-printing, robotics, chemistry—are helping humans to transcend nature's narrow definition of humanity."

"One of the earliest written references to prosthetics is found in a book published in France in 1579. That year, French surgeon Ambrose Pare (1510–1590) published his complete works, part of which described some of the artificial limbs he fitted on his amputees. As a military surgeon, Paré had re-moved many a soldier's shattered arm or leg, and he eventually began designing and building artificial limbs to help the men who had been maimed. Ambroise Paré was the official royal surgeon to four successive kings, and earned his position by practicing medicine on the battlefield, attempting to save, or at least treat, wounded soldiers. As a doctor, he was most disturbed by the reaction of some of the people whom he had saved. He found that some soldiers took their own lives rather than live without limbs, or with terrible wounds. To try to combat this problem, Paré began crafting artificial limbs. This was not new. There is evidence for the use of prostheses from the times of the ancient Egyptians. Prostheses were developed for function, cosmetic appearance and a psycho-spiritual sense of wholeness. Amputation was often feared more than death in some cultures. It was believed that it not only affected the amputee on earth, but also in the afterlife. The ablated limbs were buried and then disinterred and reburied at the time of the amputee’s death so the amputee could be whole for eternal life. One of the earliest examples comes from the 18th dynasty of ancient Egypt in the reign of Amenhotep II in the fifteenth century B.C. A mummy in the Cairo Museum has clearly had the great toe of the right foot amputated and replaced with a prosthesis manufactured from leather and wood. The first true rehabilitation aids that could be recognised as prostheses were made during the civilisations of Greece and Rome. During this period, prostheses for battle and hiding deformity were heavy, crude devices made of available materials—wood, metal and leather. Records of ancient prosthesis can be found all over the world."

"In China, King-his Tse, invented in the 500 b. C. a flying magpie of wood and bam-boo, and a wooden horse able to jump. Around year 200 B.C., Philo of Byzantium, inventor of the repetitive catapult, constructed an aquatic robot. In 206 B.C., the first Han Emperor found the Chin Shih Hueng Ti's treasure. It included a mechanical toy orchestra that moved independently. In old Greece, Archytas of Tarento (referenced in [English]] as Archytas of Tarentum, and in some references in Spanish as Architas de Tarento), philosopher, mathematician and contemporary politician of Plato, considered the father of mechanical engineering and precursory of the robotics, in-vented the [w:Screw|screw]] and the pulley, among other many devices. The materials used for the construction of robots were wood (parts with form), iron (fixed structure, supports, hinges), copper (which is mouldable and allowed the construction of thinner parts), leather (cables, footwear) and fabrics. The first models used the application of direct force to make movements, facilitated with sets of pulleys, gears and handles. In this phase the robots were replicas of the human being that made a series of simple movements. The machines began assuming tasks of aid to the man and ended up repelling their conception of the world and animated beings. The mechanics affected the study of nature, spreading to the anatomy science; of which agreed models with that conception were elaborated, such as “De Humani Corporis Fabrica” (On the workings of the human body) from Andreas Vesalius (1514–1564) who conceived the man as a complex mechanical structure."

"People have used all sorts of artificial devices probably from the beginnings of human history to help them compensate for the loss of a limb. Thus in very ancient times, the first and simplest prosthesis may have been a forked tree that was used as a crutch to help someone walk whose leg may have been badly damaged or lost in an accident or to a disease. What began as a modified crutch with a wooden or leather cup and progressed through many metamorphoses has now developed into a highly sophisticated prosthetic limb made of space-age materials."

"A 3000-year-old mummy was recently discovered sporting a prosthetic big toe. The wooden toe had been meticulously fit to the woman’s foot, with attachment straps designed for comfort. The craftsmanship was extraordinary; the toe could even flex. The toe is one of the oldest examples, but from pirates’ peg legs to Tycho Brahe’s metal nose, replacement body parts have a long and inventive history. Even before the toe’s discovery, prosthetics were known to be ancient technology. Replacement body parts are mentioned prominently in the classical literature of multiple cultures. The mythical Greek hero Pelops, accidentally ingested by the Gods, sported an ivory shoulder after his reconstruction. Herodotus mentions warriors with wooden feet, and there are examples from Asia and Rome as well."

"In France and Switzerland, from the late fifteenth through the nineteenth centuries, a variety of custom-designed limbs were built. Made of combinations of wood, metal, Leather|leather, and other materials, some of these designs were truly fantastic. Controlled by cables, gears, cranks, and springs, these limbs could be rotated and bent. There were prosthetic fingers made to grip objects. The limbs were not completely practical, as they had to be operated by a different hand, but they had their uses. For example, a hand could be cranked shut around a pen or fork. Flexing, spring-loaded legs were also available. These fantastic objects were ahead of their time: cable control was a precursor to the standard post-World War II design. Following those early designs, prosthetic limbs improved by leaps and bounds. World Wars I and II, as well as other large-scale conflicts, such as Vietnam, unfortunately increased demand for prosthetics, leading to improvements."

"There is a moment when each ultra-realistic prosthetic limb crafted by Sophie de Oliveira Barata transitions from a hunk of silicon into something more. “It happens around this point,” the artist explained, gesturing to a half-finished leg jutting mid-kick from her work bench. “I’ll know it’s happened when I handle a limb a bit roughly, and I find myself apologizing to it: ‘Oh, sorry!’” It’s an easy mistake to make. With precision molding, hand-painted veins, and real human hairs, the limbs scattered around Sophie’s studio look uncannily real: legs on the verge of dancing and hands ready to burst into applause. With these prostheses, Sophie enables her customers to conceal their absences and blend in. But the artist also caters to another kind of clientele: amputees wanting to stand out. She works with these clients to imagine the missing parts of their bodies as fantastical works of art: an arm housing a motorized coiling snake, a jewel-studded leg with embedded stereo, a bird-wing arm with a metal hook for a talon. “Instead of seeing what’s missing,” she remarked, “you see what’s there.”"

"Q: Do the clients always know what they want?"

"Q: Being so focused on other people’s limbs all the time, I wonder, what’s your relationship with your own limbs like?"

"[H]uge number of casualties in the American Civil War caused demand for artificial limbs to skyrocket. Many veterans turned to designing their own prosthetics as a response to the limiting capabilities of the limbs on offer."

"For the first time, artificial limbs were being mass-produced in response to the enormous number of casualties in World War One. In the US, the Walter Reed Army Hospital produced a large number of artificial limbs for the returning veterans. This example is of a welding attachment and other tools integrated into the limbs for amputees to return to work after the war. It wasn’t all work, however. Also in the collection of the National Museum of Health and Medicine, USA, is an attachment for playing baseball. The Walter Reed Army Hospital is still a centre for artificial limb production in the US, 100 years later. The technology continued to develop after WW1. DW Dorrance invented the split hook artificial hand shortly before World War I. It became popular with labourers after the war who were able to return to work using the attachment because of its ability to grip and manipulate objects. It’s one of the few designs that have remained relatively unchanged over the past century. Dorrance demonstrated its multi-functionality in the 1930s by driving a car using the arm. In the UK, Queen Mary’s Hospital, Roehampton, became a centre for manufacturing artificial limbs in the World War Two. It opened in 1939. In its first year, 10,987 war pensioners attended the centre, with an additional 16,251 limbs being sent by post. At the outbreak of war, the factory was expanded because of the realisation that 40,000 UK servicemen had lost limbs in WW1. However in WW2 there was around half the number of amputees. As Leon Gillis, QMH Consultant Surgeon from 1943-1967, observed, advances in surgical techniques, treatment of infections and the availability of blood transfusion after WW1 all reduced the need for amputation."

"At a lab at Johns Hopkins University, researchers are building a prosthetic hand unlike any other: It can sense pain. It’s easy to understand why you might want a prosthesis that can feel the squishiness of a grape or the warmth of another person’s hand. But pain? Well, pain could be useful, too. “If you think about how we humans use pain, it’s to protect our bodies, to prevent damage,” says Luke Osborn, a graduate student in Nitish Thakor’s lab at Hopkins, who co-authored a new paper on the pain-sensitive hand. People born without the ability to feel pain stumble through life with dangerous freedom. Babies who do not feel pain are known to chew their fingers raw; children without pain will plunge their hands into boiling water. Pain is a signal that says, Hey, watch out. “People do damage their prosthetic limbs a lot. They use them as tools they weren’t designed to be used as,” says Levi Hargrove, a bioengineer at the Shirley Ryan AbilityLab, who was not involved in the study. It’s easy, for example, to bang an unfeeling piece of plastic and metal against a table. Pain could make a prosthesis feel more real, more lifelike—less a tool and more like a natural part of the body."

"The concept of an ‘automatic’ body-powered upper limb prosthesis was pioneered by German dentist Peter Baliff in 1818. Using transmission of tension through leather straps, Baliff’s device enabled the intact muscles of the trunk and shoulder girdle to elicit motion in a terminal device attached to the amputation stump. For the first time, an amputee was able to operate his prosthesis with fluid body motions, rather than as a distinct foreign object. In the 1860s, the Comte de Beaufort in France adapted the design for use by wounded soldiers. A shoulder harness with a strap buttoned to the trousers was passed through a loop to the contralateral axilla and missing limb, allowing an amputee to manipulate the strap tension to open and close a double spring hook, or flex and extend the thumb on a simple hand with fused fingers. In 1916, German surgeon Dr Ferdinand Sauerbruch described his prosthetic design with digits controlled by transmission of upper arm muscle movements. Video captures from the era show amputees effectively using the prosthesis to drink from a teacup and even to remove a match from a box to light a cigarette. Unfortunately, due to the high cost of production, few individuals were able to afford the device."

"World War I (1914 to 1918) resulted in casualties in numbers previously unimagined. In the United States (US), amputee rehabilitation programs were created to help the >4400 amputees, of which the majority (54%) were upper limb, to regain some ability to work on farms or in factories. The distribution of prosthetics with sockets and a universal terminal device allowed the attachment of various work tools. In 1917, the Surgeon General of the US Army is-sued a landmark invitation for limb makers to meet in Washington, DC. The result was the creation of the Association of Limb Manufacturers of America, today the American Orthotic & Prosthetic Association. In Canada, a national charter in 1920 recognized the need to provide support to amputees, leading to the creation of the Amputations Association of The Great War, today known as the War Amps."

"During World War II (1939 to 1945), improved shock management and antibiotics saved lives but resulted in 3475 upper limb amputees in the US (9). The huge demand for artificial limbs led to the creation of a US Committee on Prosthetics Research and Development in 1945 and the Canadian Association of Prosthetics and Orthotics in 1955. The thalidomide tragedy (1958 to 1962) resulted in the birth of many children with shortened limbs, further driving demand and investment for improved prosthetics. In 1948, the Bowden cable body-powered prosthesis was introduced, replacing bulky straps with a sleek, sturdy cable. Despite new materials and improved craftsmanship, today’s body-powered prostheses are essentially adaptations of the Bowden design. Durable, portable and relatively affordable, body-powered prostheses allow the user an impressive range of motion, speed and force in operating a terminal device – most commonly a two-pronged hook – by changing the tension in a cable via preserved shoulder and body movements. The ability to use both hands simultaneously, rather than requiring a healthy hand to control the prosthesis, permits the user to complete tasks more efficiently. Furthermore, by sensing cable tension, the amputee is able to predict and adjust the position of the prosthesis without visual feedback. Although prolonged wearing can be uncomfortable, complicated motor tasks are limited and appearance is not human-like, body-powered prostheses are widely used"

"In 1919, a German book titled Ersatzglieder und Arbeitshilfen (Limb Substitutes and Work Aids) contained conceptual designs for the first externally powered prostheses, using pneumatic and electric power sources. Unfortunately, these revolutionary designs were too complex to be feasible with contemporary technology."

"In 1948, Reinhold Reiter, a physics student at Munich University (Munich, Germany), created the first myoelectric prosthesis, a device that amplifies surface electromyography (EMG) potentials to power motorized parts. Although Reiter published his work, it was not widely appreciated, and this potentially ground-breaking invention did not gain commercial or clinical acceptance."

"Wavelets are everywhere nowadays. Whether in signal or image processing, in astronomy, in fluid dynamics (turbulence), or in condensed matter physics, wavelets have found applications in almost every corner of physics. Furthermore, wavelet methods have become standard fare in applied mathematics, numerical analysis, and approximation theory."

"On the one hand, the concept of wavelets can be viewed as a synthesis of ideas which originated during the last twenty or thirty years in engineering (subbing coding), physics (coherent states, renormalization group), and pure mathematics (study of Calderón-Zygmund operators). As a conseuqence of these interdiscplinary origins, wavelets appeal to scientists and engineers of many different backgrounds. On the other hand, wavelets are a fairly simple mathematical tool with a great variety of possible applications."

"Wavelets were developed independently by mathematicians, quantum physicists, electrical engineers and geologists, but collaborations among these fields during the last decade have led to new and varied applications. What are wavelets, and why might they be useful to you? The fundamental idea behind wavelets is to analyze according to scale. Indeed, some researchers feel that using wavelets means adopting a whole new mind-set or perspective in processing data. Wavelets are functions that satisfy certain mathematical requirements and are used in representing data or other functions."

"Wavelet theory is nowadays a very active field of approximation theory with a wide impact on signal analysis, high-performance imaging applications, and adaptive transversal filter theory. It is concerned with the modeling of univariate and multivariate signals with a set of specific signals. The specific signals are just the wavelets. Families of wavelets are used to approximate a given signal (with respect to the L2 norm, say), and each element in the wavelet set is constructed from the same original window, the mother wavelet."

"Wavelets were introduced at the beginning of the 'eighties by J. Morlet, a French geophysicist at Elf-Aquitaine, as a tool for signal analysis in view of applications for the analysis of seismic data. The numerical success of Morlet prompted A. Grossmann to make a more detailed study of the wavelet transform, which resulted in a paper giving the mathematical foundations (see Grossmann & Morlet ..., where the title of the paper still shows the name wavelets of constant shape. In 1985, the harmonic analyst Y. Meyer became aware of this theory and he recognised many classical results inside it. Meyer pointed out to Grossmann and Morlet that there was a connection between their signal analysis methods and existing, powerful techniques in the mathematical study of singular integral operators. Then Ingrid Daubechies became involved, and all this resulted in the first construction of a special type of frames (see Daubechies, Grossmann & Meyer ..), (the concept frame generalizes the concept basis in a Hilbert space). It was also the start of a cross-fertilization between the signal analysis applications and the purely mathematical aspects of techniques based on dilations and translations."

"A Haar wavelet is the simplest type of wavelet. In discrete form, Haar wavelets are related to a mathematical operation called the Haar transform. The Haar transform serves as a prototype for all other wavelet transforms."

"The military played a significant role in the application of line telegraphy, not only in providing funds for development but also in testing the new ideas in the rigorous environment of military campaigns."

"Let me remind you that this great country was virtually created one hundred years ago by two inventions. Without them, the United States was impossible, with them, it was inevitable. Those inventions were, of course, the railroad and the electric telegraph. Today we are seeing, on a global scale, an almost exact parallel to that situation. What the railroads and the telegraph did here a century ago, the jets and communication satellites are doing now to all the world."

"... Few persons, probably, even among ornithologists realize what an enormous number of birds are killed by flying against these wires, which now form a murderous net-work over the greater part of the country. Until recently, I had myself no adequate idea of the destruction that is so quietly, insidiously, and uninterruptedly accomplished. My observations do not enable me to form even an approximate estimate of the annual mortality, and I suppose we shall never possess accurate data; but I am satisfied that many hundred thousand birds are yearly killed by the telegraph."

"Sir James Anderson and his crew on the ship Great Eastern attempted to lay down the second transatlantic cable in 1865, starting in the Irish island of Valentia. After about 1,062 miles of cable were laid down under the ocean, the cable snapped at the stern of the ship, halting the mission A second attempt was successfully made by the Great Eastern in the following year. On this journey, the crew also retrieved the lost end of the first cable and reconnected it to its original end. By the end of 1866, North America and Europe had two operating cables for telegraphic communications. Telegrams could be transmitted between North America and Europe at the average rate of 0.1 words per minute and at the cost of 10 dollars per page."

"In August 1858 President Buchanan exchanged greetings with Queen Victoria by means of the newly completed Atlantic cable. Commemorating that happy occasion, it is a pleasure to send best wishes to you on the one hundredth anniversary of the completion of the first Trans-Atlantic Cable. The development of international communications has brought the peoples of the world into close neighborhood. It is our hope that these means of communication will serve increasingly as a carrier of the message of peace for which we both work and pray."

"Outwards from London, Glasgow, Amsterdam and Hamburg there radiated the lines - shipping lines, railway lines, telegraph lines - that were the sinews of Western imperial power. Regular steamships connected the great commercial centres to every corner of the globe. They criss-crossed the oceans; they plied its great lakes; they chugged up and down its navigable rivers. At the ports where they loaded and unloaded their passengers and cargoes, there were railway stations, and from these emanated the second great network of the Victorian age: the iron rails, along which ran rhythmically, in accordance with scrupulously detailed timetables, a clunking cavalcade of steam trains. A third network, of copper and rubber rather than iron, enabled the rapid telegraphic communication of orders of all kinds: orders to be obeyed by imperial functionaries, orders to be filled by overseas merchants - even holy orders could use the telegraph to communicate with the thousands of missionaries earnestly disseminating West European creeds and ancillary beneficial knowledge to the heathen. These networks bound the world together as never before, seeming to 'annihilate distance' and thereby creating truly global markets for commodities, manufactures, labour and capital. In turn, it was these markets that peopled the prairies of the American Mid-West and the steppe of Siberia, grew rubber in Malaya and tea in Ceylon, bred sheep in Queensland and cattle in the pampas, dug diamonds from the pipes of Kimberley and gold from the rich seams of the Rand."

"Edison exhibited at the International Electrical Exhibition of Philadelphia an automatic telegraph for fac-simile transmission of despatches in Roman letters."

"If it be asked what telegraphic system is specifically announced as the most developed and extended throughout the world, the answer would seem to be definitely and summarily given in the proceedings of the International Telegraphic Convention held in Paris in March, 1865, composed of the representatives of twenty of the principal nations of Europe, assembled for the special purpose of examining the various projects, in order to adopt a uniform system, and to regulate international telegraphy for their common benefit. They thus decree in their third article; "L'appareil Morse reste provisoirement adopté pour le service des fils internationaux." Concise as is this announcement, as the result of their deliberations, it proclaims that the Morse system—an American system—is preferred for special international service throughout Europe."

"... Gauss and Weber developed an electrical two wires telegraph in 1833 for the synchronisation of observations and tested the transmission of words through an elaborate code (Stevens et al. 1838). Their scientific breakthrough led to the first commercial patent by Wheatstone in 1837 for a five wires telegraph leading immediately to the exploitation of lines between London, Liverpool, Manchester and Birmingham along the new railroad network. This telegraph was using a code able to transmit 20 letters, the other ones having to be omitted. The continental testing of this system in 1840 involved the Director of the Royal Observatory of Belgium, Quetelet and Gauss. The scientific objective being network science coordinating magnetic observatories (Quetelet, 1840). Similar developments in the United States led Morse to design a stable telegraph with a coding system able to transmit many more characters which the US Supreme Court recognized in 1854 as the only patented telegraph system."

"During the voyage of the packet ship Sully from Havre to New York, in October, 1832, a conversation arose one day in the cabin upon electricity and magnetism. Dr. Charles T. Jackson, of Boston, described an experiment recently made in Paris with an electro-magnet, by means of which elec­tricity had been transmitted through a great length of wire, arranged in circles around the walls of a large apartment. The transmission had been instantaneous, and it seemed as though the flight of electricity was too rapid to be measured. Among the group of passengers no one listened more attentively to Dr. Jackson's recital than a New York artist, named Samuel Finley Breece Morse, who was returning from a three years' residence in Europe, whither he had gone for improve­ment in his art. ... "Why," said he, when the doctor had finished, "if that is so, and the presence of electricity could be made visible in any desired part of the circuit, I see no reason why intelli­gence might not be transmitted instantaneously by electric­ity." "How convenient it would be," added one of the passen­gers, "if we could send news in that manner." "Why can't we?" asked Morse, fascinated by the idea. From that hour the subject occupied his thoughts, and he began to exercise his Yankee ingenuity in devising the requisite apparatus."

"Every day the telegraph lines over the whole country cease work for a short time for the passage of a signal which is sent out from the Observatory at Greenwich exactly at 9 a.m. At the Observatory there is a Standard Clock, and that Standard Clock is the Earth itself. The sky is the dial. Its figures are the stars, and the line of sight of a telescope is the hand which points the hours."

"At this time ambassadors remained essential due to the slowness of communications. It could take a month for a letter to travel from London to St. Petersburg; in 1822 the record for an urgent dispatch to Vienna was one week. But in the 1840s and 1850s railways started to spread across the Continent, while steamships dramatically reduced the duration of sea voyages. After the introduction of the electric telegraph in the 1870s, ciphered telegrams replaced written dispatches for urgent business. Now that messages could be sent and answered within hours, the embassies in far-flung capitals could be subject to daily supervision. In 1904 the British diplomat Sir Francis Bertie complained that an ambassador had been reduced to the status of a “damned marionette,” with the Foreign Office pulling the wires."

"Tous ceux qui se sont occupés de l'application pratique de la télégraphie électrique s'accordent facilement sur ce point, savoir, que l'immense majorité des perturbations sont sujets aux télégraphes électriques proviennent des variations dans l'intensité des courants employés. La cause des variations réside, soit dans la source des courants, soit dans les conditions variables du circuit conducteur. La première de ces causes peut être éliminée en faisant usage de sources constantes. Je me contente d'observer à cet égard que je donne la préférence à la pile de Daniell."

"(All those who have been concerned with the practical application of electrical telegraphy readily agree on this point, namely, that the immense majority of the disturbances which affect electrical telegraphs arise from variations in the intensity of the currents employed. The cause of the variations lies either in the source of the currents or in the varying conditions of the conductor circuit. The first of these causes can be eliminated by making use of constant sources. I am content, in this regard, to observe that I give preference to the Daniell cell.)"

"... once, after I came to Fort Sedgwick, the wires were said to be "down," and no communication could be had with other posts in the upper country. It was feared that the Indians had been tampering with the wires, and torn them down. But the operators went out under an escort of soldiers to see what the difficulty was. They came back again in a couple of days, and reported that the Indians had not meddled with the wires at all. But it seemed that some buffaloes in a large drove had taken the privilege of scratching their rumps against the poles, and thus tore them down; and getting their horns entangled in the wires, the wild creatures had carried off about four miles of telegraph-wire!"

"This study aims to assess the properties of foamed concrete with a density of around 500, 700, 800 and 1000 kg/m³ formed by using a synthetic polymer-based foaming agent. The distribution of pores, wet and dry density and compressive strengths were evaluated. In addition, the creep deformations... were measured."

"Foamed concrete with higher densities (700 and 800 kg/m³) showed similar characteristics of pores, which were different from those of samples with a density of 500 kg/m³."

"equal to 5.9... 5.1... 3.8... and 1.4... MPa was obtained for foamed concrete with a density of [1000, 800, 700 and 500] kg/m3, respectively. The obtained compressive strengths were higher than those found in the literature..."

"Due to sustainable development and the related reduction in energy consumption and CO2 emission... lightweight concrete, aerated concrete and foamed concrete are increasingly used..."

"Foamed concrete (FC) is classified as lightweight concrete with a density ranging from 280 to 1800 kg/m³... and with a minimum of 20% of air pore volume in the cementitious mix..."

"Foamed concrete was made using the pre-foaming method with physical foaming or mixing and the foaming method with chemical foaming..."

"Foamed concrete is characterized by its ability to flow, self-compact and self-level as well excellent thermal and acoustic insulation..."

"The compressive strength ranges from 0.21 to 10.34 MPa for a density of 300 to 1600 kg/m³ ...[in] typical application."

"Amran et al... Fadila et al... Kang... Fernando et al... and Portal et al... produced foamed concrete for use in wall panels. Rum et al... used foamed concrete as a component in a profiled composite slab. Kadela et al.., Drusa et al.., Tian et al... and Lee at al... used foamed concrete in a pavement or floor structure to transmit a load on a subsoil, including weak soil. Moreover, foamed concrete has been used in building foundations..."

"[F]oamed concrete has the potential to become a mainstream material that uses waste material successfully as a replacement for cement or fine aggregate..."

"The components of foamed concrete (type of cement... water... water/binder ratio... additives... and admixtures...) have a significant effect on its properties..."

"Even foamed concrete with a compressive strength of 70 MPa can be made by the addition of polypropylene fiber and fine and used in high-performance cement..."

"Foamed concrete (FC) is a high-quality building material with densities from 300 to 1850 kg/m3, which can have potential use in civil engineering, both as insulation from heat and sound, and for load-bearing structures. However, due to the nature of the cement material and its high porosity, FC is very weak in withstanding tensile loads; therefore, it often cracks in a plastic state, during shrinkage while drying, and also in a solid state."

"Several factors... affect the mechanical properties of FRFC, namely: fresh and hardened densities, particle size distribution, percentage of ic material... and volume of chemical foam agent. ...rheological properties ...are influenced by the properties of both fibres and foam; therefore, it is necessary to apply an additional dosage of a foam agent to enhance the adhesion and cohesion between the foam agent and the cementitious filler in comparison with materials without fibres."

"Various types of fibres allow the reduction of... autogenous shrinkage [by] a factor of 1.2–1.8 and drying shrinkage by a factor of 1.3–1.8."

"Incorporation of fibres leads to only a slight increase in the compressive strength of foamed concrete; however, it can significantly improve the (up to 4 times), tensile strength (up to 3 times) and impact strength (up to 6 times)."

"[T]he addition of fibres leads to practically no change in the heat and sound insulation characteristics of foamed concrete..."

"FRFC... has applications in various areas of construction, both in the construction of load-bearing and enclosing structures."

"Foamed concrete (FC) has recently become widespread building material for thermal insulation and structural purposes..."

"At its core, FC is made from a concrete mixture into which pre-prepared foam is introduced, creating a system of closed voids within the hardened composite..."

"FC, which is one of the varieties of cellular concrete[,] attracts... builders worldwide... has nice workability... can be used for thermal and sound isolation, flame protection as well as blast viscosity; nevertheless, low mechanical and physical characteristics... limit the scope of its application in concrete structures."

"[A]ttributable to a large amount of entrained air, the hardening mixture is subject to shrinkage to a large extent."

"The utilization of different fibres... reduce[s] shrinkage cracks and improve[s] mechanical properties, particularly tensile and flexural..."

"FC... reduces construction expenses and allows for sustainable designs with low weight..."

"To increase the target at least up to 25 MPa [3,626 psi], engineers have applied various modern approaches... In the making of high strength [cement], low water to binder ratio (w/b) and the inclusion of , , and ultrafine silica powder are recommended as a substitute to sand..."

"To increase FC’s mechanical characteristics, the water-binding ratio w/b is usually maximally reduced, as well as the use of finely dispersed ic raw materials as a replacement for fine aggregate..."

"Incorporation of randomly oriented fibres into foamed concrete can improve load transfer in different directions, and increases due to the creation of an elastoplastic composite... in load-bearing structures..."

"Considering that fibreglass also increases mechanical strength, this is an important factor in FC’s stability... High-strength foamed concrete is obtained by introducing (PP) fibre into the raw mix... Many of the currently used fibres have been investigated, including PP... blend of polypropylene with glass... ... ... steel... palm oil, coconut... and other fibres... introduced in an amount of 0.2–1.5% volume of the concrete mixture; however, in this article, the fibre content ranges upper limit has been extended to 5%. As an alternative to traditional reinforcement, one strategy with composite mesh and mesh combined with fibre has also been studied for lightweight foamed concrete (LWFC)..."

"Using synthetic and natural fibres (glass and carbon ones) in FRFC has shown excellent durability properties with reduced drying shrinkage, high modulus of elasticity and increased mechanical strength..."

"Except for some papers... the developed FRFC has a 28-day tensile and compressive strength not even more than 2.5 MPa and 50 MPa, respectively."

"[T]he use of fibres (e.g., synthetic, metallic and natural fibres) as reinforcement is reported as an effcient material added into the fibre-reinforced FC (FRFC) matrix... to bridge the cracks... [reduce] shrinkage crack[s], to enhance load transfer and to improve the hardened properties by altering the characteristic brittle behavior [in]to elastic–plastic behavior, particularly, the flexural and tensile properties."

"The fibre matrix interface and matrix densification can deliver a greater load carrying capacity of FC reliant on the toughness of the fibres. The FRFC prolongs post-crack ductility even... [with] repeating loading cycles."

"This paper reviews the production of FC, type of foam agents, method of foaming generation, type of fibres used and factors affecting the mechanical properties of FRFC. [It also provides] a critical review on the properties and behaviors of FRFC as well as... research development trends to generate... insights into the potential applications of FRFC as suitable concrete materials... robust FRFC composites, for modern buildings and civil engineering applications... to draw a more complete picture of the current state-of-the-art."

"Axel Erikson was the first to patent -based FC technology in the year 1923... The characteristics, behaviour and structural applications of FC have been widely investigated..."

"FC is reportedly proved to be superior to conventional concrete mainly due to its lower density, which helps in reducing the static construction loads, foundation volume, labour, transportation, and exploitation expenses..."

"Many countries like the United Kingdom, Germany, Philippines, Turkey, and Thailand have made the use of FC in many construction applications..."

"The bubbles’ volume varies from 6% to 35% of the total final mixture in most of FC applications..."

"Foam agents are inorganic and organic compounds... in pellet or powder foam. Organic agents are , hydrazocarbonamide, benzenesulfonyl hydrazide, dinitrosopentamethylene tetramine, toluenesulfonyl hydrazide, benzene sulfonyl , and barium azodicarboxylate. While inorganic agents are NaHCO3, NH4HCO3, (NH4)2CO3, and Ca(N3)2... foams are used as insulation spray for air-sealing buildings. stabilizer is added to enhance its slurry viscosity which consists of 20% of 40% of and 40% of hydroxypropyl methyl cellulose... [T]he various foam agents are available in E-markets worldwide."

"The chemical foamer is ordinarily protein-based, hydrolysed protein, detergents, synthetic, , soaps of resin, and glue resins... The protein foamers form in a more grounded and enclosed cell of air-void structure, which allows the incorporation of a more prominent volume of bubble and gives a higher steady bubble network. In contrast, the synthetic ones abdicate more prominent extension and hence lower density... [T]he extreme use of chemical foam volume causes a decrease in flow, density and mechanical properties of FC... However, FC’s flow is considerably influenced by the time of mixing, showing that the lengthy mixing can result in the damage of the enclosed cell of air-voids by plummeting the air content..."

"Reportedly, FC’s mechanical properties are commonly dependent on the volume of foam content instead of its dependence over the proportion of water and cement..."

"Fibre-reinforced concrete (FRC) is one containing fibrous material that improves its structural solidity..."

"Basalt fibre is cut from a continuous basalt fibre with a diameter of 17 μm, 2.5 times superior in tensile strength to superior steel. Average fibre length: 6 to 24 mm. Recommendations for the dosage of basalt fibre: 1 kilogram per 1 cubic meter of mortar or concrete. It is necessary to introduce it into the mix with water, after stirring the fibre until it is evenly distributed in the water, it is necessary to slightly increase the mixing time (up to 5–10 min) for uniform distribution in volume."

"For fibreglass concrete, an alkali-resistant (AR) fibre should be used."

"PVA fibres have a higher tensile strength [1300 MPa] than [other] synthetic[s] and are relatively economical... Due to its low density... the fibre is ideal for foamed concrete... the is 25 GPa..."

"[P]olypropylene fibre, despite the low modulus of elasticity (1.5–10 GPa), has relatively high durability... an even lower density than PVA... [and is] ideal for foam concrete. The... tensile strength is 240–760 MPa and the ultimate elongation is 15–80%..."

"[F]ibres content should be controlled within 5% to achieve optimum concrete behaviour where excessive fibres may reduce the concrete strength."

"As claimed by Lim et al... finer... aggregate size may increase the strength of FC... As the particle size grading decreased, from passing through 2.36 mm sieve to 0.60 mm and 0.10 mm sieve, the strength has an increasing trend... With finer aggregate, the workability also increases and reduces the use of compaction that potentially bursts the bubble inside concrete paste."

"Silica fume has been found to benefit concrete properties [145], especially compressive strength and durability. It was added to FRFC and was found to have a 25% increment, at most, in compressive strength..."

"With the same quantity of addition, and specimens have higher compressive strength than silica fume... [N]ano-silica also have been investigated... The 4% nano-silica was found to have more excellent mechanical properties, durability and microstructure than plain FC and 15% silica fume... Silica fume was eFFectively enhanced the flexural, compressive and tensile strength and durability with a combination of waste marble material... [T]o enhance LWFC properties, apart from traditional materials, such as FA or SF... the recycled components like the slag of various types... or glass... have also been included in the LWFC concrete matrix... [T]he pozzolans may increase the concrete strength and its durability..."

"FC is obtained from mixing base mix (normally mortar) with preformed foam (diluted foam agent with high pressure). ...FC consists of cement as binders, sand as aggregates, water, and foams. As a consideration of economic and performance enhancements, many researchers... [introduced] additives or replacements to the FC, such as fly ash... silica fume... superplasticizer... fibres, and others. There is no specific method to determine the mixing proportions. However, Kearley... proposed the calculation of mixing the proportions by the target density method, and other researchers have practiced this."

"Fibre-reinforced foam concrete mixture is poured into molds without mechanical compaction, so it must have self-sealing ."

"For optimization various performances such as consistency, rheology and workability, segregation and bleeding should be considered... These parameters mainly depend on the water/cement ratio, supplementary cementitious materials, aggregates, s, foam agents, and the type and concentration of fibre."

"[T]he mixture’s components must be precisely calculated to improve the rheology and consistency of FRFCC, attain self-sealing behaviors, and enhance the adhesion and cohesion between the foaming agent and the cementitious filler. One of the main features influencing the rheology and texture of fresh FRFCC is the mixture’s water content. Another main factor is the fibre density... the adding of light fibre negatively influences the constancy of the mixture. Besides, the rheology of FRFC worsens with excess foam due to the higher air volume, while the incorporation of SP improved the flow rate. ...[T]he "Portland cement—silica-containing additive-complex modifiers" system can significantly reduce and create easily compacted fibre-reinforced foamed concrete mixtures."

"The introduction of fibre somewhat reduces workability. The fibres large specific surface absorbs more of the cementitious mortar around the fibres and, consequently, increases the viscosity of concrete, which contributes to a slight reduction in... spreadability. However, with proper FRFC mix... improvement in workability can be achieved by introducing the optimum fibre amount."

"The principle of the segregation and bleeding (water separation) test is that after sampling, the concrete mixture is left for 15 min... After that, the upper part of the sample is poured onto a sieve with a mesh size of 5 mm. After two minutes... [t]he stratification coefficient is calculated as the mixture ratio above the sieve to [that below it]."

"[[w:Superplasticizer|[S]uperplasticizers]], if used to reduce w/c, do not cause separation or water separation. The use of a clogging micro filler (for example, finely ground limestone or quartz sand) helps to reduce... water separation... [T]he micro filler [may create] an additional "stability framework," which increases... resistance to segregation..."

"[I]nclusion of fibres [having] more than one type or more than one size... [has been] recognized as hybrid fibres."

"[C]ompressive strength decreases exponentially when concrete’s density decreases... FC’s compressive strength commonly decreases gradually as the entrapped bubbles increased; however, its strength may be enhanced by adding fibres... [F]ibres can enhance its hardened [physical] properties (including... toughness and elasticity)..."

"[O]verall strengths were mainly influenced by the factor of combined water/cement and air/cement ratio..."

"The objective of this study is to develop structural fibered foamed concrete by the addition of polypropylene fiber, , and . Foamed concrete was obtained by replacing sand with fly ash. The properties of the foamed concrete were enhanced with polypropylene fiber and fine silica fume."

"Structural fibered foamed concrete with dissimilar densities of foamed concrete (1000, 1300, 1600, and 1900 kg/m³) [62, 81, 100, 119 lb/ft³] is essential for examining compressive, flexural and splitting tensile strengths, drying shrinkage and creep."

"Fine silica fume and polypropylene fiber considerably promoted the hardened strength... [P]olypropylene fiber significantly enhanced the tensile strength and increased the creep resistance and drying shrinkage."

"[S]tructural fibered foamed concrete can be used as a substitute lightweight concrete material for the production of structural concrete applications... today."

"The neat cement with fine sand was used in the fabrication of a lightweight FC with uniformly distributed micro- or macroscopic discrete air cells..."

"FC provides unique advantages, such as thermal and acoustic insulation and resistance to fire and termite attack, lowers cost in construction, and produces... eco-friendly structures..."

"Generally, FC is designed to achieve a low compressive strength around 1–10 MPa [150 to 1,500 psi] and can be applicable in filling voids and restoring trenches but cannot be used in the construction of any structural member... To achieve the desired strength of at least 25 MPa [3,600 psi]... different innovative solutions... are economically and environmentally admissible..."

"[S]mall water-to-binder (w/b) ratio and the inclusion of (SF), ultrafine powder of silica and (FA) as an alternative of sand is recommended in the production of high-strengths FC..."

"A number of studies produced FC with compressive strength of around 50 MPa [7,300 psi] by applying special curing condition and described the relationships among strength, density, and porosity..."

"The present paper attempts to develop structural fibered foamed concrete (SFFC) with 10–70 MPa [1,500-7,300 psi] compressive strength and 1000–1900 kg/m³ [62-119 lb/ft³] density."

"Ordinary (OPC)... was used to prepare the specimens... Dry and un-compacted SF with a SiO2 content of 91.9% was used... A residue of approximately 1.56% was obtained after sieving the residue through a 45 Am sieve. ...Class F FA was used in accordance with ASTM C 618... PP fiber with a 100 μm (dia.) and 10 mm (length) was used... A [protein-based] foam agent... with an aerated density of 80 kg/m³... after diluting... [with] water... in a ratio of 1∶40 [by volume] was used... A -based super-plasticizer was applied... The dosage of the super-plasticizer and the flow of premix paste were low... [A] cohesive state was observed in the final FC mixture, in which the cementitious particle appeared... wrapped by the foam. ...[O]nly one type of middle-east sand [ 1.72] was used... spherical and smooth-surfaced..."

"Practically, a sufficient flow range in a premixed paste is a proof of the effective production of FC. When the value of flow seen was lesser than the limit, the mixes of the developed premixed paste and foam was considered in-cohesive. The binders seemed to be covered by air bubbles, which collapsed afterwards. [W]hen the value of flow was greater than the limit, seclusion happened and foam bubbles inclined to collapse."

"[A]fter 7 days of curing, the concrete without SF attained approximately 65%–80% of [compressive] strength at 28-day[s]... the specimens encompassing SF gained approximately 80%–95%... [I]n FC without SF, the 90-day strength was approximately 75%–90% of the conforming... strength. [S]pecimens encompassing SF gained around 80%–95% of the equivalent 90-day strength. Therefore, the FC with FA can gain strength over a long period."

"[L]ightweight FC material can develop strength of equal to 60 MPa [8,700 psi] with a density of approximately 60%–70% of the traditional concrete density."

"For a specified volume of foam, the PP fiber significantly improved the hardened strength. ...This advantage was also observed in the FC specimens with SF. Nevertheless... addition of PP fiber condensed the flowability of mix. Thus, we increased dosage... 0.8% fiber content was the best... level on the basis of a swap between performance enhancement and flowability loss."

"FC is a type of cement mortar containing cement, water, and stable and homogeneous foam introduced using a suitable foaming agent... regarded as self-compacting materials..."

"Other academic terms describing this material are lightweight cellular concrete, low-density foam concrete, or cellular lightweight concrete, etc..."

"The textural surface and microstructural cells make it widely used in the fields of the thermal insulation... sound absorbance... and fire resistance..."

"A great number of environmentally friendly buildings using FC as nonstructural members have been built in recent years... It is also used for bridge filling to eliminate differential settlement... In addition, the applications for prefabricated components production... building foundation... and airport buffer system are also reported..."

"Foam concrete has been commonly used in construction applications in different countries such as Germany, USA, Brazil, UK, and Canada..."

"This material has renewed interests in terms of underground engineering. This is the requirement of underground structure to control the overlying dead load... whereas the controllable density and low self-weight... could be effectively used for reducing the dead load. Other properties, such as seismic resistance, ideal coordinated deformation capacity, and easy pumping...enhance the popularity of this material..."

"FC has been quickly promoted as construction materials for tunnels and underground works. Its excellent self-flowing capacity can be used to fill voids, sink holes, disused sewage pipes, abandoned subways, and so on. The low and controlled self-weight makes it capable for load reduction or liner elements in tunnel and metro systems..."

"Tan et al.... performed an investigation on compression deformation properties of FC used as liner element for the purpose of further explaining stress and strain response. The experimental results indicated that the of FC increases with density and confining pressure, whereas the modulus of elasticity has a positive correlation only with densities regardless of confining pressure. And no notable correlation was observed between peak strain and density, but peak strain increases with confining pressure."

"Tikalsky et al.... studied the freeze-thaw durability of cellular concrete and proposed an improved freeze-thaw test method. They reported that depth of absorption was considered as a critical predictor in developing freeze-thaw-resistant concrete, which will contribute to promote effectiveness in terms of using FC as insulation material for tunnels in cold regions."

"Sun et al... explored the influence of different foaming agents on compressive strength, drying shrinkage, and workability of FC, which will be helpful to determine specification and implementation details."

"Amran et al... reviewed the composition, preparation process, and properties of FC..."

"[T]he focus of... Ramamurthy et al... is to classify literatures on foaming materials, foaming agents, cement, fillers, mix proportion, production methods, fresh and hardened properties of FC, etc."

"The objective of this review is to highlight engineering properties, material properties, and the practical applications in tunnel and underground engineering."

"There is a confusion... between FC and similar materials in early literatures, i.e., aerated concrete and air-entrained concrete... However, one definition (i.e., FC is defined as a cementing material with the minimum of 20% foams by volume in the mixed plastic mortar) introduced by Van Dijk... clearly distinguish the FC from aerated concrete... and air-entrained concrete... The closed air-voids system in FC notably reduces its density and weight and at the same time produces efficient insulation and fire resistance capacity..."

"The first Portland cement-based FC was patented by Axel Eriksson in 1923, and then, small-scale commercial production activities were launched... Valora carried out the first comprehensive investigation in the 1950s..."

"Rudnai... and Short and Kinniburgh... [in 1963] systematically reported the composition, properties, and applications of the FC..."

"FC was initially envisaged as a void filling, stabilization, and insulation material..."

"The booming development of this new constituent material in buildings and constructions was enhanced in the late 1970s... A government-oriented assessment on FC could be seen as a milestone event to further widening FC applications."

"Over the past 30 years, FC are widely used for the bulk filling... ditch repair, retaining wall...bridge backfill... slab structure of concrete floor... and housing insulation... etc. ...Currently, people are increasingly interested in using it as a nonstructure or semistructure member for underground engineering, such as grouting works for tunnels, damage treatment, and liner structures."

"The basic components of FC consist of (1) water, (2) binder, (3) foaming agent, (4) filler, (5) additive, and (6) fiber."

"The water requirement for constituent material depends on composition, consistency and stability of the mortar body..."

"[L]ower water content leads to a hard mixture... easily resulting in bubble bursting..."

"[H]igher water content causes mixture too thin to accommodate bubbles... causing bubbles separating from the mixture..."

"The (ACI) recommends that mixed water should be fresh, clean, and drinkable..."

"Cement is the most commonly used binder. The ordinary , rapid hardening Portland cement, calcium sulphoaluminate cement, and high-alumina can be used in ranges between 25% and 100% of the binder content..."

"The determines FC density by controlling generation rate of the bubbles in cement paste. The resin-based was one of the earliest used... [S]ynthetic, protein-based, composite and synthetic s have been derived and developed... the most frequently used are synthetic and protein-based..."

"Various fillers such as , , powder, granulated blast furnace , and fly-ash ceramicite... have been widely adopted... to enrich FC mechanical performances... Addition of these fillers is helpful to improve mix proportion design, long-term strength, and reduce costs. In addition, some fine aggregates such as fine sand... recycled glass powder... and surface modified chip... are commonly used for production of high-density FC."

"Commonly used additive includes the water reducer, water-proofing additive, retarder, coagulation accelerator, etc. s are... considered to enhance compatibility... [T]hey are defined as water reducers to improve performance of fresh concrete... and there is no notable impact on concrete segregation..."

"A variety of fibers are added into FC so as to improve strength and reduce shrinkage. They are mainly ... glass and polypropylene... red ... palm oil, steel... coconut... waste paper ... [and] carbon... which usually introduced in ranges between 0.2% and 1.5% of the mixture volume."

"Foamed concrete differentiates from (a) gas or aerated concrete, where the bubbles are chemically formed through the reaction of powder with calcium hydro oxide and other alkalies released by cement hydration and (b) air entrained concrete, which has a much lower volume of entrained air... for durability."

"28 days strength and dry ... vary according to its composition, largely its air voids content, but usually... range... 1.0 to 25.00 N/mm2 and 400 to 1800 kg/m3. The plastic density... is about 150 to 200 kg/m3 higher than... dry density."

"Foamed light weight concrete... bricks, blocks or poured in-situ is used for over flat roofs... cold storage walls or... s for low-rise buildings."

"Fire rating of foamed concrete is far superior to... brick work or dense concrete."

"[D]ry ingredients like cement, sand, sand + fly ash or fly ash alone shall be... thoroughly mixed to ensure even distribution... [B]locks may be de-moulded after 24 hours"

"[F]oam... shall be added in measured amount to the slurry of cement, sand, fly ash and water in the batch mixer... mixing to get uniform consistency... of desired wet unit weight..."

"After curing [per IS: 456-2000], the blocks shall be allowed to dry under shade for a period 2 to 3 weeks... to complete their initial shrinkage..."

"Sample [first trial] mix proportions [by weight of water (W), ordinary Portland cement grade 53 (OPC 53 grade or (C) in Note below), fly ash (FA), and fine sand (FS) passing 4 mm IS sieve] ... are given in table- 1, 2 & 3. However, conclusive... proportions by actual trials may be worked out... for required workability, plastic density and compressive strength."

"If [used,] ... dosage should not be more than 0.2[% by weight of cement] bwc."

"Ignore the amount of water... in the foam in the mix design calculation."

"Determine the amount of air (kg/m3) in the mix from... the target density of the foam."

"Usually... cement content lie[s] between 300 to 500 kg/m3. ...[G]ain in strength is small above... 500 kg/m3."

"Fly ash is added... up to 100% of the [ordinary Portland cement] OPC content, to enhance workability and increase long-term strength... Because of greater surface area... [these] mixes have a greater water demand... [F]ly ash... leads to a more uniform bubble structure... which... improve[s] some... engineering properties..."

"Fly ash can be used as a total replacement for sand to produce... a dry density of up to 1400 kg/m3."

"[T]rial mixes should be done... to determine workability... plastic density... [and compressive strength.] Specimens shall be cast and tested for... compliance of required specifications."

"To minimize shrinkage... [water] ratio[s] should be kept as low as possible."

"This CPAR project was undertaken to test, demonstrate, and commercialize a new construction system... [which] employs stay-in-place forms made from fiberglass-reinforced cement boards."

"Foamed concrete is also referred to as aerated or cellular concrete. Foamed concretes are lightweight concretes [typically... with densities ranging from 320 to 1,920 kg/m3 (20 to 120 lb/ft3)] that are prepared by adding air cells... typically... from 0.1 to 1 mm (0.004 to 0.04 in.) in diameter (Aldrich and Mitchell 1976)."

"The foamed concrete used in this investigation was a 500- to 880-kg/m3 (31-to 55-lb/ft3) mixture that did not contain aggregate. Admixture materials, dispersing agents, chopped synthetic fiber, and s were added to the foamed concrete to improve the strength and toughness and produce a more uniform material. The particular type of foamed concrete prepared for this research program would be classed as a neat-cement cellular concrete modified with admixtures (Legatski 1994)."

"Foamed concrete is a desirable material... because of its durability, thermal-insulating, and fire-retarding properties. The low density of foamed concretes produces a substantial reduction in the dead weight of the structures in which it is used."

"Foamed-concrete panels are... an economical component in construction because they are not subject to attack by insects or fungi. Foamed concrete will not degrade or depolymerize because of oxidation or photolytic reactions. In the event of fire, foamed concrete will slow the spread of the fire and will not emit smoke or toxic fumes (Short and Kinniburgh 1981, 1978)."

"As the density of foamed concrete decreases, the strength properties and thermal conductivity decrease... Foamed concretes are generally used in nonstructural applications such as roof decks over metal formwork, void-filling grouts, and shock-absorbing materials for special applications."

"Foamed-concrete blocks or panels are produced as cast-in-place (or cast-onsite) or precast units. Precast blocks or panels are generally manufactured by using chemical additives to generate gas bubbles in the concrete mixture. ...[C]uring is typically done under high-pressure steam."

"Cast-onsite operations typically use rotating drum or paddle mixers. The cellular structure is produced by introducing a preformed, aqueous-based foam similar to a fire-fighting foam."

"The new method of using cast-in-place foamed concrete with stay-in-place forms... offers several advantages. ...[It] can be adapted to a variety of requirements, and the new construction system... [a]llows hollow spaces to be blocked out in the walls for the installation of utilities or for steel-reinforced concrete pilasters that are integral with the wall."

"The strength of foamed concrete made with conventional portland cement can be maximized by combining the mixture design that offers the highest paste strength with the optimum mixing techniques. Previous engineering studies (Pier and Pahl 1994) show that for a given density of foamed concrete, the strength... increases as the strength of the cured paste increases..."

"High-strength concretes designed with conventional materials typically improve the strength of the cured concrete by reducing the water/cement ratio (w/c) using a high-range water-reducing admixture (HRWRA) and by replacing up to 15 percent of the mass of cement with . ...The addition of silica fume... allows the formed by the hydration of the cement to react and form additional calcium silicate hydrate gel that increases the strength of the paste. The design strategy used in this study involved investigating a silica-fume replacement of up to 15 percent and the use of high-range water reducers that allowed samples with w/c's as low as 0.44 to be prepared."

"Pier and Pahl (1994) also found that the strongest foamed concretes were made without using any fine aggregate. The fine-aggregate particles acted as stress concentrators, and samples made with any fine aggregate were weaker than the neat-cement formulations."

"An organic fiber (nylon) was used in the mixture in quantities that are approximately 1 percent by volume of the mixture... to increase the fracture toughness of the mixture."

"The character of the foaming agent (synthetic organic or various types of hydrolyzed protein) can produce significant changes in strength (Pier and Pahl 1994). Animal protein-based foaming agents and synthetic foaming agents were both evaluated in this study."

"[I]nvestigators examined several different types of mixers and developed a technique for mixing that involved the use of a high-shear mixer to make a paste and a paddle mixer to blend foam and fiber with the paste."

"Three important variables, the proportion of silica-fume replacement, the type of HRWRA, and the w/c, were evaluated... A methocellulose thickening agent (Methocel F4M, Dow Chemical Co...) was added to each batch to reduce the rate of settling of the cement particles. The mixing operation... involved dry blending the Methocel with portland cement in a 7-to-l by volume mixture prior to adding the cement to the water in the high-shear mixer. The paste was prepared by combining the water, HRWRA, dispersing agent, cement, and silica fume in a 0.36-m3 (12-ft3) capacity high-speed shear mixer. The addition of foam adds water to the mixture, and the quantity of the water depends on the density of the foam. ...[I]t was necessary to add sufficient water to the high-shear mixer to get the cement paste to mix efficiently and to flow out of the mixer."

"[P]aste was removed from the high-shear mixer and placed in a Stone Model 1265PM paddle mixer... Litecrete R11937 foaming agent... was used... diluted 39 to 1 by volume, and the diluted solution was foamed using a Cellufoam Systems Model 620 Foam Generator... Foam was added to adjust the density to the target level, and fiber was added to the foamed concrete. The foamed concrete was then removed from the paddle mixer and placed in the form..."

"Silica-fume replacement above 20 percent presents problems with regard to water demand even when HRWRA is used. ...In two of the three attempts to place foamed concrete with a 20-percent silica-fume replacement, the foamed concrete collapsed."

"The most successful placements and highest strengths were obtained with 10-percent silica-fume replacement. The best flow characteristics and best strengths were obtained with a mixture that contained 10-percent silica-fume replacement and at w/c = 0.62."

"The HRWRA ingredient that performed best was Sikament S-10 ESL (Sika Corp...) ...a synthetic HRWRA formulated around a vinyl co-polymer. The manufacturer recommends this HRWRA for use in concretes containing silica fume or other micro-silica products. The manufacturer's recommended addition rate is 390 to 1,300 ml/100 kg of cement. Additions of... 1,200 ml/100 kg of combined cement and silica fume were used..."

"Typically, the samples from the lowest part of the column were 16 to 32 kg/m3 (1 to 2 lb/ft3) denser than the samples from the top of the column. In extreme cases, variations as high as 320 kg/m3 (20 lb/ft3) were noted. Denser samples are stronger. In these low-density concretes, a 16- to 32-kg/m3 (1- to 2-lb/ft3) density difference can increase the unconfined compressive strength by 100 kPa (14.5 psi) or more."

"The target densities for the panels were set at 480 to 560 kg/m3 (30 to 35 lb/ft3) with target unconfined compressive strengths (28 days) of over 895 kPa (130 psi)."

"A high temperature can cause the foam to collapse because it expands the gas bubbles in the concrete and lowers the surface tension in the foam. Based on the results of the temperature measurements, a synthetic foaming agent that was considered to have better tolerance at high temperatures was substituted for the animal protein-based foam that had been used... where the foamed concrete had collapsed."

"The goal was to produce materials that had an air-dried density under 640 kg/m3 (40 lb/ft3) and an unconfined compressive strength of over 690 kPa (100 psi) after curing for 28 days..."

"The composition used in the optimum mixture proportion is presented in Table 6."

"The peak interior temperatures in the panels reached approximately 30°C above ambient... The temperature changes did not produce any thermal or shrinkage cracking. The foam collapse observed stopped when the synthetic foaming agent was used. No problems with regard to flash setting or loss of workability were noted in the temperature ranges observed... [N]o special procedures (such as cooling the ingredients) or the use of low-heat cements are needed in foamed-cement panel production for the panel sizes used in this investigation when ambient temperatures are on the order of 20 to 25 °C."

"Basically there is only one method for making concrete light i.e., by the inclusion of air in concrete. This is achieved in actual practice by three different ways. (a) By replacing the usual mineral aggregate by cellular porous or light-weight aggregate. (b) By introducing gas or air bubbles in mortar. This is known as aerated concrete. (c) By omitting sand fraction from the aggregate. This is called 'no-fines' concrete."

"[S]tructural light-weight concrete is... strong enough to be used for structural purposes. Light-weight concrete can... be classified on the purpose for which it is used, such as structural light weight concrete, non-load bearing concrete and insulating concrete. The aerated concrete which was mainly used for insulating purposes is now being used for structural purposes sometimes in conjunction with steel reinforcement. The aerated concrete is more widely manufactured and used in the Scandinavian countries; whereas in U.K., France, Germany and U.S.A. owing to the production of large scale artificial industrial light-weight aggregate, light-weight aggregates concrete is widely used."

"There are several ways in which aerated concrete can be manufactured. (a) By the formation of gas by chemical reaction within the mass during liquid or plastic state. (b) By mixing preformed stable foam with the slurry. (c) By using finely powdered metal (usually powder) with the slurry and made to react with the liberated during the hydration process, to give out large quantity of gas. This hydrogen gas when contained in the slurry mix, gives the cellular structure. Powdered may also be added in place of aluminum powder. and bleaching powder have also been used instead of metal powder. But this practice is not widely followed at present."

"Gasification method is of the most widely adopted methods using aluminium powder or such other similar material. This method is adopted in the large scale manufacture of aerated concrete in the factory wherein the whole process is mechanised and the product is subjected to high pressure steam curing i.e... the products are autoclaved. Such products will suffer neither retrogression of strength nor dimensional instability."

"The practice of using preformed foam with slurry is limited to small scale production and in situ work where small change in the dimensional stability can be tolerated. But... any density desired... can be made in this method."

"[T]he addition of a moderate amount of air to any concrete mix will bring a marked increase in resistance to the disintegrating effects of freezing and thawing."

"The application of air-entrainment to the concrete mix, for the improvement of its durability, workability and uniformity, is one of the most important developments in concrete technology."

"The improvement in durability with the use of proper amounts of entrained air in concrete is so great that variations in the , within the usual working range, do not have the same significance as formerly."

"The deliberate addition of air to concrete seemed, from a superficial examination, to be contradictory to the principle that high density is a pre-requisite of high quality. But the concept of density of concrete actually means: freedom from honeycombing and large voids resulting from inadequate consolidation or from segre­gation. Air entrainment, by enabling some reduction in water-cement ratio, tends to improve the quality of the concrete paste, and by improving workability tends to reduce segregation and improves con­solidation of the concrete."

"First experiments proved that, to obtain desirable properties of air-entrained concretes, entrained air must be approximately three percent above that which is normally present in the concrete, this brings the total amount of air to between four and five percent..."

"There are various air entraining admixtures for concrete that can be either interground with the cement during the manufacturing process or added separately at the mixer. Many of them are essentially saponifying agents, they react with the alkaline constituents of the cement to form soap and from the soap, form minute air bubbles."

"[A]ir-entrainment adds to the fluidity or slump of concrete and it is possible to restore the initial degree of stiffness by adding solids or subtracting water. Air cannot be added to a mixture without introducing unbalances in consistency and yield of the plastic concrete. ...[T]he strength of the hardened concrete depends on the consistency of the plastic concrete. Experiments have shown that for the same workability, less water is required than for ordinary concrete."

"The chief ways of producing aerated or gas concrete are by mixing air entraining agents with cement or cement and sand in special high speed or whisking mixers, by adding a given quantity of pre-formed foam to a cement or a cement sand mortar in an ordinary mixer and by adding aluminum or powder to a cement mortar."

"Aerated concrete has a very high drying shrinkage but this can be reduced by high pressure steam curing in which case or natural can with advantage be introduced to the mix."

"Owing to its high drying shrinkage... [lightweight concretes] use for cast in situ should be restricted to cases where shrinkage cracks are not of much importance."

"Lightweight concrete is normally accepted as that having a density range between 25 and 110 lb per cu ft, but even lower densities can be used when it is required solely for insulating purposes."

"Lightweight concrete can be produced in three ways: 1. By omitting the fine aggregate. This is called a 'no-fines' concrete. 2. By using lightweight aggragate. 3. By using lightweight aggregate and producing what is generall known variously as 'aerated concrete', 'cellular concrete', 'gas concrete', 'porous concrete', and 'foamed concrete'. This should not be confused with air entrained concrete which has a weight nearly equal to that of ordinary concrete and in which the proportion of air is limited to about 9 per cent."

"Aerated, cellular or gas concrete can be made in weights ranging from about 25 lb per cu ft or even less, to 110 lb per cu ft. Its most useful range is perhaps between 40 and 60 lb per cu ft. It can produced in the following ways: 1. By mixing air entraining agents with cement or cement and sand in special high speed or whisking mixers. If an ordinary mixer is used it is doubtful if sufficient air would be entrained to obtain a density as low as 90 lb per cu ft. The Cheecol process belongs to this class. 2. By making foam and and adding a given quantity of this to a cement or cement and sand mortar in the mixer. An ordinary mixer is suitable for this method. The Pyrene process belongs to this class. 3. By adding hydrogen peroxide (H2O2) to the concrete. 4. By the use of calcium carbide (Ca2C2). 5. By adding aluminum powder or powder to a cement mortar."

"Very careful mixing of the mortar with the air entraining or other agent is essential in all cases if a uniform result is to be obtained."

"If the lightest concretes (25 lb per cu ft and under) are required a neat cement mortar is used, but for heavier weights (40 lb per cu ft and above) sand, preferably very fine, may be added up to a cement/sand ratio... of 1 to 4. A higher strength/weight ratio can be obtained if cement only is used, but the addition of sand cheapens the product."

"The Use of Air Entraining Agents... The normal density produced from this system ranges from 60 to 100 lb per cu ft and the proportion of air entraining agent may be about 0.25 per cent of the mix. The quantity of air entraining agent, the cement/sand ratio, the speed of the mixer and the time of mixing are the chief factors..."

"The Use of Preformed Foam... [A]lmost any desired density of concrete can be produced... dependent almost entirely on the amount of foam added. About two per cent by volume of a foaming agent is added to the water and mixed with compressed air in a mixing tube. ...The foam is delivered ... direct into the mixer in which the cement or cement sand mortar has previously been prepared. The product can be cast in situ or used for making precast blocks."

"The effects of the incorporation of each of nine different air-entraining admixtures in concrete were investigated by the making of a large number of batches of concrete under carefully controlled laboratory conditions. The results of tests on the plastic and hardened concrete specimens from batches made in parallel with and without each admixture are presented and discussed."

"Different air entraining agents produce different amounts of air entrainment, depending upon the elasticity of the film of the bubble produced, and the extent to which the surface tension is reduced. Similarly, different quantities of air entraining agents will result in different amounts of air entrainment."

"Water/cement ratio is one of the important factors affecting the quantity of air. At very low water/cement ratio, water films on the cement will be insufficient to produce adequate foaming action. At intermediate water/cement ratio (viz. 0.4 to 0.6) abundant air bubbles will be produced. But at a higher water/cement ratio although to start with, a large amount of air entrainment is produced, a large proportion of the bubbles will be lost progressively with time."

"The grading of aggregate has shown good influence on the quantity of air entrainment. It was established that the quantity of air increased from the lowest of sand to a peak at about F.M. of 2.5, and, thereafter, decreased sharply. The sand fraction of 300 and 150 microns showed a significant effect on the quantity of air entrainment. The higher quantity of these fractions resulted in more air entrainment."

"The amount of air entrainment is found to increase with the mixing time up to a certain time and thereafter with prolonged mixing the air entrainment gets reduced."

"The temperature of concrete at the time of mixing was found to have a significant effect on the amount of air entrainment. The amount of air entrainment decreases as the temperature of concrete increases."

"The constituents of the cement especially the alkali content plays an important part in the entrainment of air in concrete. Similarly, the fineness of cement is also a factor."

"Air content is... reduced by the process of compaction, on account of the movement of air bubbles to the surface... [A]s much as 50 per cent of the entrained air may be lost after vibration for 2 1/2 minutes and as much as 80 per cent may be lost by vibration for 9 minutes."

"[A]dmixtures used in conjunction with air entraining agents will... significantly affect the amount of air entrained. The use of in concrete will reduce the amount of air entrained. Similarly, the use of calcium chloride also has the tendency to reduce and limit air entrainment."

"I interrupted the old man in midsentence and stood straight up from the rocker. It felt as if a pulse of energy ran up my spine, compressing my lungs, electrifying my skin, bringing the hairs on the back of my neck to full alert. I moved closer to the fireplace, unable to absorb its heat. "Are you saying what I think you're saying?" My brain was taking on too much knowledge. There was overflow and I needed to shake off the excess. The old man looked at nothing and said, "We are God's debris.""

"Gwell eo beroù war an oaled / Eget e ti marc'h rous ar pried (Better skewers on the fireplace than in the spouse's russet horse shed.)"

"In another moment Alice was through the glass, and had jumped lightly down into the Looking-glass room. The very first thing she did was to look whether there was a fire in the fireplace, and she was quite pleased to find that there was a real one, blazing away as brightly as the one she had left behind. "So I shall be as warm here as I was in the old room," thought Alice: "warmer, in fact, because there'll be no one here to scold me away from the fire. Oh, what fun it'll be, when they see me through the glass in here, and can't get at me!""

"In the winter on a Sunday afternoon, I can spend six hours in front of the fireplace, just looking at the flames and thinking. In the evening, I’m drunk with beautiful thoughts. My wife says to me, ‘What are you looking at?’ I say, ‘The fire.’ We have to take a step backward."

"There is nothing of greater interest connected with the Durham furnace than the manufacture of iron stove plates and their artistic embellishments. ...[T]he manufacture of iron stoves, for heating of buildings, was begun at the furnace about 1741, when controlled by George Taylor, James Logan and James Morgan, father of General , iron master. These were called the "Adam and Eve" stoves from the figures, cast on them. ...In 1745, the furnace began casting the famous "Franklin Stove," or fire-place, and continued until it blew out, 1793. They were favorably received and with minor improvements, extensively manufactured. It was the first stove made that could be utilized for baking and cooking, having an extra door above the fuel door, a plate the whole length of the stove and a descending flue the same as the Prince Rupert stove, 1678, cast in England. It was improved, 1754, by a door on one side. This was known as the Philadelphia pattern, though smaller in size. The Franklin sold at £4. 6s, each at the furnace, and at Philadelphia £18 per ton, the price varying with the metal. About 1775, a stove pattern, artistically decorated with a bony skeleton inscribed on the center of the side plates, grasping a bone in one hand in the act of striking a man, near the end of the plate, while another figure on rear end of plate is standing in a frightened attitude looking on the unequal battle. Beneath the figures is the following inscription:HIR. FEIT. MIT. MIR. DER. BITER. TOTER. BRINCT. MICH.INTOTS. NO.A free translation of this Swedish-German is "Here (man) presumes to fight with me, bitter death, but he cannot overcome death.""

""Do not repine, my friends," said Mr. Pecksniff, tenderly. "Do not weep for me. It is chronic." And with these words, after making a futile attempt to pull off his shoes, he fell into the fireplace."

"Announced by all the trumpets of the sky, Arrives the snow, and, driving o'er the fields, Seems nowhere to alight: the whited air Hides hills and woods, the river, and the heaven, And veils the farmhouse at the garden's end. The sled and traveller stopped, the courier's feet Delayed, all friends shut out, the housemates sit Around the radiant fireplace, enclosed In a tumultuous privacy of storm."

"Here's a list of Dutch paintings intended for the Salon: - Israëls, ...https://philamuseum.org/collection/object/102868 Old Friends (Silent Conversation) an old man sits in a hut by the fireplace in which a small piece of peat barely glows in the twilight. For it's a dark hut... His dog, who's grown old with him, sits beside him–those two old creatures look at each other, they look each other in the eye, the dog and the old man. ...Nothing else – the twilight, the quiet, the loneliness of those two old creatures, man and dog... that old man thinking... that face – a melancholy, satisfied, submissive expression.. .I definitely know of no other painting than this Israëls that can stand up to Millet's 'Death and the Woodcutter'... on the other hand I know of no other painting that could stand up to this Israëls than Millet's Death and the woodcutter... Moreover, I feel in my mind an irresistible desire to bring together that painting by Israëls and that other by Millet and make them complement each other.."

"It happened because one day I was sitting one side of the fireplace, and my wife was sitting on the other, and I suddenly said to her, "Wouldn’t it be a good idea to write a story about some boys on an island, showing how they would really behave, being boys and not little saints as they usually are in children’s books.” And she said, "That’s a first-class idea! You write it!" So I went ahead and wrote it."

"Lele liilii ka lehu o kapuahi (He is scattering the ashes of the fireplace)."

"The prisoner was no longer fastened to the bed save by one leg. Before the seven men had had time to recover themselves and spring upon him, he had bent over to the fireplace, reached his hand towards the furnace, then rose up, and now Thenardier, the Thenardiess, and the bandits, thrown by the shock into the back part of the room, beheld him with stupefaction, holding above his head the glowing chisel, from which fell an ominous light, almost free and in a formidable attitude."

"The grate had been removed from the wide overwhelming fireplace, to make way for a fire of wood, in the midst of which was an enormous log glowing and blazing, and sending forth a vast volume of light and heat; this I understood was the Yule-log, which the Squire was particular in having brought in and illumined on a Christmas eve, according to ancient custom."

"Our society, it turns out, can use modern art. A restaurant, today, will order a mural by Míro in as easy and matter-of-fact a spirit as, twenty-five years ago, it would have ordered one by Maxfield Parrish. The president of a paint factory goes home, sits down by his fireplace — it looks like a chromium aquarium set into the wall by a wall-safe company that has branched out into interior decorating, but there is a log burning in it, he calls it a fireplace, let’s call it a fireplace too — the president sits down, folds his hands on his stomach, and stares at two paintings by Jackson Pollock that he has hung on the wall opposite him. He feels at home with them; in fact, as he looks at them he not only feels at home, he feels as if he were back at the paint factory."

"A good night for the fireplace to be crackling with flames - or so he figured, Crumpling the papers he could only see As testimonials to long plateaus of emptiness."

"A woman who taught at Berkeley dropped in on me once and saw a book burning in the fireplace. She pointed at it in terror, and I explained that it was a crummy ghostwritten life of a movie star and that it was an act of sanitation to burn it rather than sending it out into the world which was already clogged with too many copies of it. But she said, "You shouldn’t burn books" and began to cry."

"And I live with the dead – my mother, my sister, my grandfather, my father... .Every day is the same – my friends have stopped coming – their laughter disturbs me, tortures me.. ..my daily walk round the old castle becomes shorter and shorter, it tires me more and more to take walks. The fire in the fireplace is my only friend – the time I spend sitting in front of the fireplace gets longer and longer.. ..at its worst I lean my head against the fireplace overwhelmed by the sudden urge – Kill yourself and then it’s all over. Why live? I light the candle – my huge shadow springs across half the wall, clear up to the ceiling and in the mirror over the fireplace I see the face of my own ghost."

"All these people come to see the White House and they see practically nothing that dates back before 1948. Every boy who comes here should see things that develop his sense of history. For the girls, the house should look beautiful and lived-in. They should see what a fire in the fireplace and pretty flowers can do for a house; the White House rooms should give them a sense of all that. Everything in the White House must have a reason for being there. It would be sacrilege merely to "redecorate" it—a word I hate. It must be restored—and that has nothing to do with decoration. That is a question of scholarship."

"There is one great thing that you men will all be able to say after this war is over and you are home once again. You may be thankful that twenty years from now when you are sitting by the fireplace with your grandson on your knee and he asks you what you did in the great World War II, you won't have to cough, shift him to the other knee and say, "Well, your Granddaddy shoveled shit in Louisiana." No, Sir, you can look him straight in the eye and say, "Son, your Granddaddy rode with the Great Third Army and a Son-of-a-Goddamned-Bitch named Georgie Patton!"

"In small rooms... the chimney often smokes unless the door or window be open, not only because the fire devours and carries off a large quantity of the air of the room, but also because the fire requires a continual supply of air for its support; so that, if a proportional quantity of air which the fire consumes and sends up the chimney does not enter the room (which it cannot do in small rooms with a large fire), the fire languishes, and the smoke increases, since flame is nothing more than a kindled smoke, and smoke is only an extinguished flame, or, at least, not yet kindled."

"I don't approve of open fires. You can't think, or talk or even make love in front of a fireplace. All you can do is stare at it."

"Take a look at the simplest of objects. Let's take, for example, an old chair. It seems like nothing. But think of the universe comprised within it: the sweaty hands cutting the wood that used to be a robust tree, full of energy, in the middle of a luxuriant forest by some high mountains. The loving work that built it, the joyful anticipation of the one who bought it, the tired bodies it has helped, the pains and the joys it must have endured, whether in fancy halls or in a humble dining room in your neighbourhood. Everything, everything shares life and has its importance! Even the most worn down of chair carries inside the initial force of the sap climbing from the earth, out there in the forest, and will still be useful the day when, broken into kindling, it burns in some fireplace."

"Lyndon's gone and dragged Nasser away from the fireplace and onto the balcony again. Once you get him out there, it's a helluva job to get him back to the fireplace again."

"Till more effectual methods can take place, it would be of great service, to oblige all those Trades who make use of large Fires, to carry their Chimnies much higher into the air than they are at present..."

"Workmen should be consulted, and encouraged to make experiments, whether a particular construction of the Chimnies would not assist in conveying off the Smoke, and in fending it higher into the air before it is dispersed."

"[N]ear half the children that are born and bred in London die under two years of age. ...[T]he constant and unremitting Poison is communicated by the foul Air, which, as the Town still grows larger, has made regular and steady advances in its fatal influence. ...[W]e are accustomed to read with great composure of the deaths of thosands of infants, suffocated every Year by Smoke and Stenches which good policy might in a great measure remove."

"And what is all this, but that Hellish and dismall Cloud of SEA-COALE? which is not onely perpetually imminent over her head... so universally mixed with the otherwise wholsome and excellent Aer, that her Inhabitants breathe nothing but an impure and thick Mist, accompanied with a fuliginous and filthy vapour, which renders them obnoxious to a thousand inconveniences, corrupting the Lungs, and disordering the entire habit of their Bodies; so that Catharrs, Phthisicks, Coughs and Consumptions, rage more in this one City, than in the whole Earth besides."

"[N]ot from the Culinary fires, which for being weak, and lesse often fed below, is with such ease dispelled and scattered above, as it is hardly at all discernible, but from some few particular Tunnells and Issues, belonging only to Brewers, Diers, Lime-burners, Salt, and Sope-boylers, and some other private Trades, One of whose Spiracles alone, does manifestly infest the Aer, more than all the Chimnies of London put together besides."

"Whilst these are belching it forth their sooty jaws, the City of London resembles the face rather of Mount Ætna, the Court of Vulcan, , or the Suburbs of Hell, than an Assembly of Rational Creatures... For when in all other places the Aer is most Serene and Pure, it is here Ecclipsed with such a Cloud of Sulphure, as the Sun itself... is hardly able to penetrate... and the weary Traveller, at many Miles distance, sooner smells, than sees the City to which he repairs."

"It seems that those who have hitherto built or caused chimneys to be erected, have only taken care to contrive in the chambers certain places where wood may be burnt, without making a due reflection that the wood in burning ought to warm those chambers, and the persons who are in them; at least, it is certain that but a very little heat is felt of the fire made in the ordinary chimneys, and that they might be ordered so as to send forth a great deal more, only by changing the disposition of their jambs and wings."

"A plate of iron or copper bowed or bended after such a manner as is not at all disagreeable to the sight; a void behind, divided by certain small iron bands or partition plates, forming several spaces that have a communication one with another; a little vent hole in the middle of the hearth, a register plate in the upper part of the funnel; and for some shafts, a capital on the top, make up the whole construction and workmanship of our modern chimney. Now, can there be anything more simple or plain, or more easy to execute?"

"To be able to kindle a fire speedily, and make it, if you please, flame continually, whatever wood is burning, without the use of bellows; to give heat to a spacious room, and even to another adjoining, with a little fire; to warm one's self at the same time on all sides, be the weather ever so cold, without scorching; to breathe a pure air always fresh, and to such a degree of warmth as is thought fit; to be never annoyed with smoke in one's apartment, nor have any moisture therein; to quench by one's self, and in an instant, any fire that may catch in the tunnel of a chimney; all these are but a few of the effects and properties of these wonderful machines, not withstanding their apparent simplicity. Since I used this sort of chimney, I have not been troubled one moment with smoke, in a lodging which it rendered before untenable as soon as a fire was lighted; I have always inhaled, even during the sharpest seasons, a fresh air like that of the spring. In 1709, water that froze hard everywhere else very near the hearth, did not congeal at night in my chamber, though the fire was put out before midnight; and all that was brought thither in the day soon thawed; neither did I ever perceive the least moisture in winter, not even during thaws."

"In an edition of the author's writings on electrical and philosophical subjects, published in London in the year 1769, the following note is appended to this tract. "Soon after the foregoing piece was published, some persons in England, in imitation of Mr. Franklin's invention, made what they call Pennsylvanian Fire-places, with improvements; the principal of which pretended improvements is, a contraction of the passages in the air-box, originally designed for admitting a quantity of fresh air, and warming it as it entered the room. The contracting [of] these passages gains indeed more room for the grate, but in a great measure defeats their intention. For, if the passages in the air-box do not greatly exceed in dimensions the amount of all the crevices by which cold air can enter the room, they will not considerably prevent, as they were intended, the entry of cold air through the crevices.""

"[A]ny new proposal for saving the wood, and for lessening the charge and augmenting the benefit of fire, by some particular method of making and managing it, may at least be thought worth consideration."

"1. Air is rarefied by heat, and condensed by cold, that is, the same quantity of air takes up more space when warm than when cold. This may be shown... Take any clear glass bottle (a stript of the straw is best), place it before the fire, and, as the air within is warmed and rarefied, part of it will be driven out of the bottle; turn it up, place its mouth in a vessel of water, and remove it from the fire; then, as the air within cools and contracts, you will see the water rise in the neck of the bottle, supplying the place of just so much air as was driven out. Hold a large hot coal near the side of the bottle, and, as the air within feels the heat, it will again distend and force out the water. Or, fill a bladder not quite full of air, tie the neck tight, and lay it before a fire as near as may be without scorching the bladder; as the air within heats, you will perceive it to swell and fill the bladder, till it becomes tight, as if full blown; remove it to a cool place, and you will see it fall gradually, till it becomes as lank as at first."

"2. Air rarefied and distended by heat is specifically lighter than it was before, and will rise in other air of greater density. As wood, oil, or any other matter specifically lighter than water, if placed at the bottom of a vessel of water will rise till it comes to the top; so rarefied air will rise in common air, till it either comes to air of equal weight, or is by cold reduced to its former density."

"[I]n any chimney, the air over the fire is rarefied by the heat, becomes lighter, and therefore immediately rises in the funnel, and goes out; the other air in the room (flowing towards the chimney) supplies its place, is rarefied in its turn, and rises likewise; the place of the air thus carried out of the room, is supplied by fresh air coming in through doors and windows, or, if they be shut, through every crevice with violence, as may be seen by holding a candle to a key-hole."

"If the room be so tight as that all the crevices together will not supply so much air as is continually carried off, then, in a little time, the current up the funnel must flag, and the smoke, being no longer driven up, must come into the room."

"1. Fire... throws out light, heat, and smoke (or fume.) The [first] two... move in right lines, and with great swiftness; the latter is but just separated from the fuel, and then moves only as it is carried by the stream of rarefied air; and without a continual accession and recession of air, to carry off the smoky fumes, they would remain crowded about the fire, and stifle it."

"2. Heat may be separated from the smoke as well as from the light, by means of a plate of iron, which will suffer heat to pass through it without the others."

"3. Fire sends out its rays of heat, as well as rays of light, equally every way; but the greatest sensible heat is over the fire, where there is, besides the rays of heat shot upwards, a continual rising stream of hot air, heated by the rays shot round on every side."

"[C]onsider the fire-places heretofore in use, viz. 1. The large open fire-places used in the days of our fathers, and still generally in the country, and in kitchens. 2. The newer-fashioned fire-places, with low breasts and narrow hearths. 3. Fire-places with hollow backs, hearths and jambs of iron, (described by M. Gauger, in his tract entitled La Méchanique de Feu,) for warming the air as it comes into the room. 4. The Holland stoves, with iron doors opening into the room. 5. The German stoves, which have no opening in the room where they are used, but the fire is put in from some other room, or from without. 6. Iron pots, with open charcoal fires, placed in the middle of a room."

"1. The first of these methods has generally the conveniency of two warm seats, one in each corner; but they are sometimes too hot to abide in, and, at other times, incommoded with the smoke; there is likewise good room for the cook to move, to hang on pots, &c. Their inconveniences are, that they almost always smoke, if the door be not left open; that they require a large funnel, and a large funnel carries off a great quantity of air, which occasions what is called a strong draft to the chimney, without which strong draft the smoke would come out of some part or other of so large an opening, so that the door can seldom be shut; and the cold air so nips the backs and heels of those that sit before the fire, that they have no comfort till either screens or settles are provided (at a considerable expense) to keep it off, which both cumber the room, and darken the fire-side. A moderate quantity of wood on the fire, in so large a hearth, seems but little; and, in so strong and cold a draft, warms but little; so that people are continually laying on more. In short, it is next to impossible to warm a room with such a fire place; and I suppose our ancestors never thought of warming rooms to sit in; all they purposed was, to have a place to make a fire in, by which they might warm themselves when cold."

"2. Most of these old-fashioned chimneys in towns and cities have been, of late years, reduced to the second sort mentioned, by building jambs within them, narrowing the hearth, and making a low arch or breast. It is strange, methinks, that though chimneys have been so long in use, their construction should be so little understood till lately, that no workman pretended to make one which should always carry off all smoke, but a chimney-cloth was looked upon as essential to a chimney. This improvement, however, by small openings and low breasts, has been made in our days; and success in the first experiments has brought it into general use in cities, so that almost all new chimneys are now made of that sort, and much fewer bricks will make a stack of chimneys now than formerly. An improvement so lately made may give us room to believe, that still farther improvements may be found to remedy the inconveniences yet remaining. For these new chimneys, though they keep rooms generally free from smoke, and, the opening being contracted, will allow the [house] door to be shut, yet, the funnel still requiring a considerable quantity of air, it rushes in at every crevice so strongly, as to make a continual whistling or howling; and it is very uncomfortable, as well as dangerous, to sit against any such crevice. Many colds are caught from this cause only, it being safer to sit in the open street; for then the pores do all close together, and the air does not strike so sharply against any particular part of the body."

"[M]any of the diseases proceeding from colds, as fevers, pleurisies, &c., fatal to very great numbers of people, may be ascribed to strong-drawing chimneys, whereby, in severe weather, a man is scorched before, while he is froze behind."

"In the mean time, very little is done by these chimneys towards warming the room; for the air round the fire-place, which is warmed by the direct rays from the fire, does not continue in the room, but is continually crowded and gathered into the chimney by the current of cold air coming behind it, and so is presently carried off."

"In both these sorts of fire-places, the greatest part of the heat from the fire is lost; for, as fire naturally darts heat every way, the back, the two jambs, and the hearth drink up almost all that is given them, very little being reflected from bodies so dark, porous, and unpolished; and the upright heat, which is by far the greatest, flies directly up the chimney. Thus five sixths at least of the heat (and consequently of the fuel) is wasted, and contributes nothing towards warming the room."

"3. To remedy this, the Sieur Gauger gives, in his book, entitled La Méchanique de Feu, published in 1709, seven different constructions of the third sort of chimneys mentioned above, in which there are hollow cavities made by iron plates in the back, jambs, and hearths, through which plates the heat passing warms the air in those cavities, which is continually coming into the room fresh and warm. The invention was very ingenious, and had many conveniences; the room was warmed in all parts, by the air flowing into it through the heated cavities; cold air was prevented rushing through the crevices, the funnel being sufficiently supplied by those cavities; much less fuel would serve, &c. But the first expense, which was very great, the intricacy of the design, and the difficulty of the execution, especially in old chimneys, discouraged the propagation of the invention; so that there are, I suppose, very few such chimneys now in use. The upright heat, too, was almost all lost in these, as in the common chimneys."

"4. The Holland iron stove, which has a flue proceeding from the top, and a small iron door opening into the room, comes next to be considered. Its conveniences are, that it makes a room all over warm; for, the chimney being wholly closed except the flue of the stove, very little air is required to supply that, and therefore not much rushes in at crevices, or at the door when it is opened. Little fuel serves, the heat being almost all saved; for it rays out almost equally from the four sides, the bottom, and the top, into the room , and presently warms the air around it, which, being rarefied, rises to the ceiling, and its place is supplied by the lower air of the room, which flows gradually towards the stove, and is there warmed, and rises in its turn, so that there is a continual circulation till all the air in the room is warmed. The air, too, is gradually changed, by the stove-door's being in the room, through which part of it is continually passing, and that makes these stoves wholesomer, or at least pleasanter than the German stoves... But... There is no sight of the fire... When the room is warm, people, not seeing the fire, are apt to forget supplying it with fuel... The change of air is not carried on quite quick enough; so that, if any smoke or ill smell happens in the room, it is a long time before it is discharged. For these reasons the Holland stove has not obtained much among the English (who love the sight of the fire) unless in some workshops..."

"5. The German stove is like a box, one side wanting. It is composed of five iron plates, screwed together, and fixed so as that you may put the fuel into it from another room, or from the outside of the house. It is a kind of oven reversed, its mouth being without, and body within, the room that is to be warmed by it. This invention certainly warms a room very speedily and thoroughly with little fuel; no quantity of cold air comes in at any crevice, because there is no discharge of air which it might supply, there being no passage into the stove from the room. ...Its inconveniences are, that people have not even so much sight or use of the fire as in the Holland stoves, and are, moreover, obliged to breathe the same unchanged air continually, mixed with the breath and perspiration from one another's bodies, which is very disagreeable to those who have not been accustomed to it."

"6. Charcoal fires in pots are used chiefly in the shops of handicraftsmen. They warm a room (that is kept close, and has no chimney to carry off the warmed air,) very speedily and uniformly; but, there being no draft to change the air, the sulphurous fumes from the coals (be they ever so well kindled before they are brought in, there will be some,) mix with it, render it disagreeable, hurtful to some constitutions, and some times, when the door is long kept shut, produce fatal consequences."

"To avoid the several inconveniences, and at the same time retain all the advantages of other fire-places, was contrived the PENNSYLVANIAN FIRE-PLACE, now to be described."

"[T]he flame and smoke will ascend and strike the top... which will thereby receive a considerable heat. The smoke, finding no passage upwards, turns over the top of the air-box, and descends between it and the back plate to the holes in the bottom plate, heating, as it passes, both plates of the air-box, and the said back plate; the front plate, bottom and side plates are also all heated at the same time. The smoke proceeds in the passage that leads it under and behind the false back, and so rises into the chimney."

"The air of the room, warmed behind the back plate, and by the sides, front, and top plates, becoming specifically lighter than the other air in the room, is obliged to rise; but the closure over the fire place hindering it from going up the chimney, it is forced out into the room, rises by the mantel-piece to the ceiling, and spreads all over the top of the room, whence being crowded down gradually by the stream of newly-warmed air that follows and rises above it, the whole room becomes in a short time equally warmed."

"At the same time, the air, warmed under the bottom plate and in the air-box, rises and comes out of the holes in the side plates, very swiftly, if the door of the room be shut, and joins its current with the stream before mentioned, rising from the side, back, and top plates."

"The air that enters the room through the air-box is fresh, though warm; and, computing the swiftness of its motion with the areas of the holes, it is found that near ten barrels of fresh air are hourly introduced by the air-box; and by this means the air in the room is continually changed, and kept at the same time sweet and warm."

"It is to be observed, that the entering air will not be warm at first lighting the fire, but heats gradually as the fire increases."

"Its advantages above the common fire-places are, 1. That your whole room is equally warmed, so that people need not crowd so close round the fire, but may sit near the window, and have the benefit of the light for reading, writing, needlework, &c. They may sit with comfort in any part of the room... 2. If you sit near the fire, you have not that cold draft of uncomfortable air nipping your back and heels, as when before common fires, by which many catch cold, being scorched before, and... froze behind. 3. If you sit against a crevice, there is not that sharp draft of cold air playing on you, as in rooms where there are fires in the common way; by which many catch cold, whence proceed coughs, catarrhs, tooth-aches, fevers, pleurisies, and many other diseases. 4. In case of sickness, they make most excellent nursing-rooms; as they constantly supply a sufficiency of fresh air, so warmed at the same time as to be no way inconvenient or dangerous. A small one does well in a chamber; and, the chimneys being fitted for it, it may be removed from one room to another, as occasion requires, and fixed in half an hour. The equal temper, too, and warmth of the air of the room, is thought to be particularly advantageous in some distempers... 5. In common chimneys, the strongest heat from the fire, which is upwards, goes directly up the chimney, and is lost; and there is such a strong draft into the chimney, that not only the upright heat, but also the back, sides, and downward heats are carried up the chimney by that draft of air; and the warmth given before the fire, by the rays that strike out towards the room, is continually driven back, crowded into the chimney, and carried up by the same draft of air. But here the upright heat strikes and heats the top plate, which warms the air above it, and that comes into the room. The heat likewise, which the fire communicates to the sides, back, bottom, and air-box, is all brought into the room; for you will find a constant current of warm air coming out of the chimney corner into the room. Hold a candle just under the mantel-piece, or breast of your chimney, and you will see the flame bent outwards; by laying a piece of smoking paper on the hearth, on either side, you may see how the current of air moves, and where it tends, for it will turn and carry the smoke with it. 6. Thus, as very little of the heat is lost, when this fire-place is used, much less wood will serve you, which is a considerable advantage where wood is dear. 7. When you burn candles near this fire-place, you will find that the flame burns quite upright, and does not blare and run the tallow down, by drawing towards the chimney, as against common fires. 8. This fire-place cures most smoky chimneys, and thereby preserves both the eyes and furniture. 9. It prevents the fouling of chimneys; much of the lint and dust that contributes to foul a chimney being, by the low arch, obliged to pass through the flame, where it is consumed. Then, less wood being burnt, there is less smoke made. Again, the shutter, or trap-bellows, soon blowing the wood into a flame, the same wood does not yield so much smoke as if burnt in a common chimney; for, as soon as flame begins, smoke in proportion ceases. 10. And, if a chimney should be foul, it is much less likely to take fire. If it should take fire, it is easily stifled and extinguished. 11. A fire may be very speedily made in this fire-place by the help of the shutter, or trap-bellows... 12. A fire may be soon extinguished by closing it with the shutter before, and turning the register behind, which will stifle it, and the brands will remain ready to rekindle. 13. The room being once warm, the warmth may be retained in it all night. 14. And lastly, the fire is so secured at night, that not one spark can fly out into the room to do damage."

"With all these conveniences, you do not lose the pleasing sight nor use of the fire, as in the Dutch stoves, but may boil the tea-kettle, warm the flat irons, heat heaters, keep warm a dish of victuals by setting it on the top, &c."

"We leave it to the political arithmetician to compute how much money will be saved to a country, by its spending two thirds less of fuel; how much labor saved in cutting and carriage of it; how much more land may be cleared by cultivation; how great the profit by the additional quantity of work done, in those trades particularly that do not exercise the body so much, but that the workfolks are obliged to run frequently to the fire to warm themselves; and to physicians to say, how much healthier thick-built towns and cities will be, now half suffocated with sulphury smoke, when so much less of that smoke shall be made, and the air breathed by the inhabitants be consequently so much purer."

"[T]he builder of chimneys has been left to grope his way in the dark without assistant; and in almost every instance his attempts to improve upon the practice of his predecessors, have been unsuccessful; so that the inhabitants of these countries, with justice, complain that the inconveniencies felt in new houses from this cause, usually are more than sufficient to counterbalance all the elegancies that modern refinement has introduced into the dwellings..."

"[T]he causes which produce smoke in rooms... may be all reduced to one of the three following general classes: 1. A faulty construction of the tube, vent, or chimney itself; 2. To some fault in the other parts of the building, and a wrong position of the chimney with respect to these; or, 3. To an improper situation of the house with respect to external objects."

"The earth is every where surrounded with a great body of air, that is called the atmosphere. This air is a thin elastic fluid, possessing some qualities peculiar to itself, but subjected in general to the same physical laws with other fluids; and of consequence it hath a constant tendency to preserve an exact equilibrium in all its parts; so that if at any time the weight of it at one place is diminished, the heavier air rushes from all sides towards that point, till the equilibrium be again restored."

"Many are the causes that may tend to destroy this equilibrium of the atmosphere; but the only one that it imports our present discussion to explain the effects of, is ."

"When heat acts upon the air, it immediately makes it expand to a great degree, so as that the same quantity of it occupies a much larger space than formerly. Hence... where a fire is kindled, the air immediately contiguous to it will be heated, and of consequence rarefied, and made lighter..."

"[A]s it is an invariable rule among all fluids, that those which are lightest rise upwards, and at length swim upon the top of such as are more weighty... so... that when any particles of the same fluid are... rendered lighter, or more weighty, than other parts... they either rise to the top, and give place to the more dense and weighty parts of it, or sink to the bottom, and force the warmer fluid to the surface."

"It is owing to this cause that the water at the top of a caldron, before it begins to boil, is always as warm, or warmer, than what is below:—for the particles of water that touch the bottom are no sooner acted upon by the heat below, than they become warmer, and more expanded, than those immediately above them, and therefore rise directly upwards, and give place to denser cold particles, which are forced in their turn to ascend in like manner towards the top."

"In the same manner... when the air contiguous to a fire is heated... it is immediately expanded very much; and therefore instantly rises upwards, till it reaches the higher regions of the atmosphere, or is cooled by gradually mixing with the denser air it meets with in its ascent:—and as its place contiguous to the fire is immediately occupied by the cold dense air around it, which rushes from every side towards that point, it is heated and rarefied in its turn, and ascends in the same manner, carrying the smoke that rises from the burning body along with it."

"It is in this manner that the constant suction of air towards every fire is produced; and from this cause proceeds the continual tendency of smoke to ascend from the surface of the earth, unless where some circumstance interrupts the course of nature."

"[M]en... disccovered, that when the fire was surrounded with a wall to any considerable height, the motion of the wind was interrupted by it, and the smoke allowed to rise upwards till it reached the top of the building.—The free ascent of this disagreeble vapour... was promoted by the addition of a roof... Hence... in every part of the globe the first and most simple huts... are circular buildings, with a conical roof; in the middle of which, for the most part, is left a hole for the emission of the smoke; the fire having been placed in the centre of the building immediately below the opening, which served instead of a window, as well as a vent-hole for the smoke."

"[A]s luxury encreased, and the elegant arts became more common... fire places were contracted to a narrower size.——The grate, instead of being placed in the middle of a large area, with seats around it, was pushed close to the back wall. The width of the opening of the vent, was found to be sufficient if it contained the whole of the grate;—and as the fire warmed the room more effectually when it came well forward, the grate was brought as far into the apartment as could be done.—The pipe of the chimney was contracted to such dimensions as to admit of being contained within the thickness of an ordinary wall, and reduced to that elegant and commodious tube now known by the name of chimney."

"[H]igh [longer] chimneys... have a greater suction of air, and are less liable to vent ill, than low ones, and this is one principal reason why in the same house the chimneys in the garrets, and the higher stories, are more apt to vent ill, than those on the floor, where the chimneys are of necessity longer. A smoky chimney, therefore, may sometimes be cured, merely by raising it higher..."

"A chimney may not only be defective by having the mantle too high, or by being too wide from side to side, but also by being too deep between the fore-side and the back, as is often the case in very old houses. In this case, the distance between the fire and the mantle is so great, that much air passes up without being sufficiently rarefied... This fault may be sometimes cured, by bringing the grate a little forward, which, by making the fire act more powerfully upon the mantle, rarefies the air more in its passage."

"[W]hen the grate is brought forward, there is a great vacancy left between it and the back of the chimney, so... air passes under the grate, and ascends behind it very little rarefied; so... there will be as much lost in this way as will be gained in the other: and as there is not enough of heated air... to make the vapour ascend with rapidity, they are often choaked with thick fuliginous vapours hanging in them, almost in equilibrio with the rest of the atmosphere, so that the least puff of wind beats them down the chimney, and pushes the smoke into the room; whereas, when it is far back, it is driven down upon the hearth, and rises upwards again when the gust is over, and a great deal of it is catched within the mantle as it rises, which in the other case would have been dispersed through the room."

"When this is the case the most effectual method... is, to bring the grate forward till the forepart of it is immediately under the inner edge of the mantle; then build up the vacancy at the back of it, the whole width of the fire-place from side to side, raising it perpendicularly till it is as high as the back of the grate, and then bending it forward towards the mantle, as... fig 4. When it is as high as the workman can reach, let it be suddenly turned backward again, sloping a little upward... then fit a sheet of milled iron to the inside of the mantle, making it slant a little upward toward the back... a small distance above the new... masonry, and extending within a few inches of the back wall... By this construction all the air that enters into the chimney is made to pass immediately above the fire, between it and the heated iron... as the back of the fire-place is bent a little forward above the grate... the heat is likewise reflected into the room with the greater force... [I]f the smoke is accidentally beat down the chimney by a sudden gust of wind, it will be catched by the sheet of Iron, and prevented from coming into the room."

"[Y]ou desire me to give you... my thoughts upon the Construction and Use of Chimneys... I embrace willingly this leisure... to comply... as it will not only fhew my regard to... a friend, but may... be of some utility to others; the doctrine of chimneys appearing not to be as yet generally well understood, and mistakes respecting them being attended with constant inconvenience, if not remedied; and with fruitless expence, if the true remedies are mistaken."

"Having lit a pipe of tobacco, plunge the stem to the bottom of a decanter half filled with cold water; then putting a rag over the bowl, blow through it, and make the smoke descend in the stem of the pipe, from the end of which it will rise in bubbles through the water; and being thus cooled will not afterwards rise to go out through the neck of the decanter, but remain spreading itself, and resting on the surface of the water. This shews that smoke is really heavier than air; and that it is carried upwards only when attached to, or acted upon, by air that is heated, and thereby rarefied and rendered specifically lighter than the air in its neighbourhood."

"Smoke being rarely seen but in company with heated air, and its upward motion being visible, though that of the rarefied air that drives it is not so, has naturally given rise to... error."

"[A]ir is a which has weight as well as others, though about eight hundred times lighter than water; that heat makes the particles of air recede from each other and take up more space, so that the same weight of air heated will have more bulk [volume] than equal weights of cold air which may surround it, and in that case must rise, being forced upwards by such colder and heavier air, which presses to get under it, and take its place."

"That air is so rarefied or expanded by heat, may be proved to... by a lank blown bladder, which laid before a fire will soon swell, grow tight, and burst."

"Another experiment may be, to take a glass tube... open at both ends, and fixed upright on legs, so that it need not be handled, for the hands might warm it: at the end of a quill, fasten five or six inches of the finest light filament of silk, so that it may be held either above the upper end of the tube or under the lower end, your warm hand being at a distance by the length of the quill. If there were any motion of air through the tube, it would manifest itself by its effect on the silk [Fig. I]; but if the tube and the air in it are of the same temperature with the surrounding air, there will be no such motion. ...Warm the tube, and you will find as long as it continues warm, a constant current of air entering below and passing up through it, till discharged at the top; because the warmth of the tube... rarefies that air, and makes it lighter than the air without, which therefore presses in below, forces it upwards, follows and takes its place, and is rarefied in its turn."

"[N]o form of the funnel of the chimney has any share in its operation or effect respecting smoke, except its height. The longer the funnel if erect, the greater its force when filled with heated and rarefied air, to draw in below and drive up the smoke (if one may in compliance with custom use the expression draw), when in fact it is the superior weight of the surrounding atmosphere that presses to enter the funnel below, and so drives up... the smoke and warm air..."

"I have been... particular in explaining these first principles, because for want of clear ideas respecting them, much fruitless expence has been occasioned... whole stacks having been pulled down and rebuilt with funnels of different forms, imagined more powerful in drawing smoke, but having still the same height and the same opening below, have performed no better than their predecessors."

"What is it then which makes a smoky chimney..? The causes of this effect which have fallen under my observation, amount to nine..."

"Smoky chimneys in a new house are [as] such frequently from mere want of air. The workmanship of the rooms being all good... true and tight... The doors and the sashes too, being worked with truth, shut with exactness so that the room is as tight as a snuff-box."

"Now, if smoke cannot rise... unless other air be admitted to supply its place; and if therefore no current of air enter the opening of the chimney, there is nothing to prevent the smoke coming out into the room."

"If... a column of air, equal to the content of the funnel, must be discharged, and an equal quantity supplied from the room below; it will appear absolutely impossible that this operation should go on if the tight room is kept shut: for were there any force capable of drawing constantly so much air out of it, it must soon be exhausted, like the receiver of an air-pump, and no animal could live in it."

"Those therefore who stop every crevice in a room to prevent the admission of fresh air, and yet would have their chimney carry up the smoke, require inconsistencies, and expect impossibilities."

"I have seen the owner of a new house in despair, and ready to sell it for much less than it cost, conceiving it uninhabitable, because not a chimney in any one of its rooms would carry off the smoke, unless a door or window were left open."

"Much expence has... been made to alter and amend new chimneys which had really no fault: in one house... of a nobleman in Westminster, that expence amounted to... three hundred pounds... and after all, several... alterations were ineffectual, for want of understanding the true principles."

"When you find... that opening the door or a window enables the chimney to carry up all the smoke, you may be sure that want of air from without was the cause of its smoking: I say from without, to guard you against a common mistake of those who may tell you, the room is large, [and] contains abundance of air sufficient to supply any chimney... These reasoners are ignorant, that the largeness of a room, if tight, is... of small importance, since it cannot part with a chimneyful of its air, without occasioning so much vacuum..."

"It appearing plainly... that some of the outward air must be admitted, the question will be, How much is absolutely necessary? ...To discover this quantity, shut the door gradually, while a middling fire is burning, till... the smoke begins to come out into the room; then open it a little, till you perceive the smoke comes out no longer: there hold the door, and observe the width of the open crevice... thence... your room requires an entrance for air equal in area.. I have found ...thirty-six square inches, to... serve for most chimneys."

"High funnels, with small and low openings, may indeed be supplied through a less space [in area]; because... the force of levity being greater in such funnels, the cool air enters the room with greater velocity, and consequently more enters in the same time. This, however, has its limits..."

"It remains then to be considered, how and where this necessary quantity of air from without is to be admitted, so as to be least inconvenient. For, if... the air proceeds directly to the chimney, and... comes cold to your back and heels, as you sit before your fire you feel the... inconvenience."

"Various have been the contrivances to avoid this: such as bringing in fresh air through pipes, in the jams of the chimney, which, pointing upwards, should blow the smoke up the funnel; opening passages into the funnel above, to let in air for the same purpose. But these produce an effect contrary to that intended; for, as it is the constant current of air passing from the room through the opening of the chimney into the funnel, which prevents the smoke coming out into the room, if you supply the funnel by other means, or in other ways, with the air it wants, and especially if that air be cold, you diminish the force of that current, and the smoke, in its efforts to enter the room, finds less resistance."

"The wanted air must... indispensibly be admitted into the room to supply what goes off through the opening of the chimney. M. Gauger... proposes, with judgment, to admit it above the opening of the chimney; and to prevent inconvenience from its coldness, he directs its being made to pass in its entrance through winding cavities made behind the iron back and sides of the fire-place; and under the iron hearth-plate; in which cavities it will be warmed, and even heated, so as to contribute much, instead of cooling, to the warming of the room. This invention is excellent in itself, and may be used with advantage in building new houses; because the chimneys may then be so disposed as to admit conveniently the cold air to enter such passages: but, in houses built without such views, the chimneys are often so situated as not to afford that convenience, without great and expensive alterations. Easy and cheap methods, though not quite so perfect in themselves, are of more general utility; and such are the following:"

"Few can imagine the difference of climate between the upper and lower parts of such a room, who have not tried it by the thermometer, or by going up a ladder till their heads are near the ceiling. It is then among this warm air that the wanted quantity of outward air is best admitted."

"This may be easily done by drawing down about an inch the upper sash of a window; or, if not moveable, by cutting such a crevice through its frame... it will be well to place a thin shelf... to conceal the opening; and sloping upwards, to direct the entering air... In some houses, the air may be admitted by such a crevice... near the ceiling and over the opening of the chimney. ...[T]he entering cold air will there meet with the warmest rising air from before the fire, and be soonest tempered by the mixture. The same kind of shelf should also be placed here."

"Another way... is to take out an upper pane of glass in one of your sashes: set it in a tin frame, giving it two springing angular sides, and then replacing it with hinges below [Fig. 2], on which it may be turned to open more or less above. ...By drawing this pane in more or less, you may admit... air... Its position will naturally throw that air up and along the ceiling."

"A second cause of the smoking of chimneys is, their openings in the room being too large... Architects... have no other ideas of proportion in the opening of a chimney, than what relate to symmetry and beauty... while its true proportion, respecting its function and utility, depends on quite other principles... The proportion then to be regarded, is what relates to the height of the funnel. For... funnels in the different stories of a house are necessarily of different heights or lengths... [T]he openings of the longest funnels may be larger, and that those of the shorter funnels should be smaller. For if there be a large opening to a chimney that does not draw strongly, the funnel may... be furnished with the air it demands by a partial current... on one side of the opening... the other side free of any opposing current, may permit the smoke to issue there into the room."

"Much... of the force of draft in a funnel depends on the degree of rarefaction in the air it contains; and that depends on the nearness to the fire... in entering the funnel. If it can enter far from the fire on each side, or far above the fire in a [too] wide or high opening, it receives little heat in passing by the fire, and the contents of the funnel is by that means less different in levity from the surrounding atmosphere, and its force in drawing consequently weaker."

"Hence if too large an opening be given to chimneys in upper rooms, those rooms will be smoky."

"On the other hand, if too small openings be given to chimneys in the lower rooms, the entering air operating too directly and violently on the fire; and afterwards strengthening the draft as it ascends the funnel, will consume the fuel too rapidly."

"If you suspect that your chimney smokes from the too great dimension of its opening, contract it by placing moveable boards so as to lower and narrow it gradually, till you find the smoke no longer issues into the room. The proportion so found will be that which is proper... and you may employ the bricklayer or mason to reduce it accordingly."

"[I]n building new houses... I would have the openings in my lower rooms about thirty inches square and eighteen deep, and those in the upper only eighteen inches square and not quite so deep; the intermediate ones diminishing in proportion as the height of funnel diminished. ...The same depth is nearly necessary to all, the funnels being all made of a size proper to admit a chimney-sweeper."

"If in large and elegant rooms custom or fancy should require the appearance of a larger chimney, it may be formed of expensive marginal decorations, in marble, &c. In time, perhaps, that which is fittest in the nature of things may come to be thought handsomest."

"But at present, when men and women in different countries shew themselves dissatisfied with the forms God has given to their heads, waists, and feet, and pretend to shape them, more perfectly, it is hardly to be expected that they will be content always with the best form of a chimney. And there are some, I know, so bigotted to the fancy of a large noble opening, that, rather than change it, they would submit to have damaged furniture, fore eyes, and skins almost smoked to bacon."

"The plague of a smoking Chimney is proverbial; but there are many other very great defects in open Fire-places, as... commonly constructed... which, being less obvious, are seldom attended to; and there are some of them... fatal in their confequences... and... cost the lives of thousands every year... By a cause which might be so easily removed!—by a cause whose removal would tend to promote comfort and convenience in so many ways."

"There are various causes by which Chimnies may be prevented from carrying smoke; but there are none that may not easily be discovered and completely removed."

"Those who will take the trouble to consider the nature and properties of elastic s,—of air,—smoke,—and vapour,—and to examine the laws of their motions, and the necessary consequences of their being rarified by heat, would perceive that it would be as much a miracle if smoke should not rise in a Chimney, (all hindrances to its ascent being removed,) as that water should refuse to run in a syphon, or to descend in a river."

"The whole mystery, therefore, of curing smoking Chimnies is comprised in this simple direction,—find out and remove those local hindrances which forcibly prevent the smoke from following its natural tendency to go up the Chimney; or rather, to speak more accurately, which prevents its being forced up the Chimney by the pressure of the heavier air of the room."

"[T]hat cause which will... almost universally be found to operate, is one which it is always very easy to discover, and as easy to remove,—the bad construction of the Chimney in the neighbourhood of the Fire-place."

"I have never been obliged, except in one... instance, to have recourse to any other method of cure than merely reducing the Fire-place and the throat of the Chimney, or that part of it which lies immediately above the Fire-place, to a proper form, and just dimensions."

"[O]f above an hundred and fifty Fire-places which have been altered in this city, under my direction, within these last two months, there is not one which has not answered perfectly well. ...the saving of fuel, arising from these improvements of Fire-places, amounts in all cases to more than half, and in many cases to more than two thirds of the quantity formerly consumed."

"Now as the alterations in Fire-places which are necessary may be made at a very trifling expence... as no iron work, but merely a few bricks and some mortar, or a few small pieces of fire-stone, are required; the improvement in question is very important, when considered merely with a view to economy; but it should be remembered, that not only a great saving is made of fuel by the alterations proposed, but that rooms are made much more comfortable, and more salubrious;—that they may be more equally warmed, and more easily kept at any required temperature;—that all draughts of cold air from the doors and windows towards the Fire-place, which are so fatal to delicate constitutions, will be completely prevented;—that in consequence of the air being equally warm all over the room, or in all parts of it, it may be entirely changed with the greatest facility, and the room completely ventilated, when this air is become unfit for respiration, and this merely by throwing open for a moment a door opening into some passage from whence fresh air may be had, and the upper part of a window; or by opening the upper part of one window and the lower part of another."

"And as the operation of ventilating the room, even when it is done in the most complete manner, will never require the door and window to be open more than one minute; in this short time the walls of the room will not be sensibly cooled, and the fresh air which comes into the room will, in a very few minutes, be so completely warmed by these walls that the temperature of the room, though the air in it be perfectly changed, will be brought to be very nearly the same as it was before the ventilation."

"As long as any fire is kept up in the room, there is so considerable a current of air up the Chimney, notwithstanding all the reduction that can be made in the size of its throat, that the continual change of air in the room which this current occasions will, generally, be found to be quite sufficient for keeping the air in the room sweet and wholesome..."

"Those who have any doubts respecting the very great change of air or ventilation which takes place each time the door of a warm room is opened in cold weather, need only set the door... wide open for a moment, and hold two lighted candles in the door-way, one near the top of the door, and the other near the bottom... The violence with which the flame of that above will be driven outwards, and that below inwards by the two strong currents of air which, passing in opposite directions, rush in and out of the room at the same time, will [convince them] that the change of air which actually takes place must be very considerable... and these currents will be stronger, and consequently the change of air greater, in proportion as the difference is greater between the temperatures of the air within the room and of that without."

"The great fault of all the open Fire-places, or Chimnies, for burning... an open fire, now in common use, is, that they are much too large; or rather it is the throat of the Chimney or the lower part of its open canal, in the neighbourhood of the mantle, and immediately over the fire, which is too large. This opening has hitherto been left larger than otherwise it probably would have been made, in order to give a passage to the Chimney-sweeper; but I shall show... how a passage for the Chimney-sweeper may be contrived without leaving the throat of the Chimney of such enormous dimensions as to swallow up and devour all the warm air of the room, instead of merely giving a passage to the smoke and heated vapour which rise from the fire, for which last purpose alone it ought to be destined."

"I shall endeavour to write in such a manner as to be easily understood by those who are most likely to profit by the information I have to communicate, and consequently most likely to assist in bringing into general use the improvements I recommend."

"As the immoderate size of the throats of Chimnies is the great fault of their construction, it is this fault which ought always to be first attended to in every attempt which is made to improve them; for... if the opening left for the passage of the smoke is larger than is necessary for that purpose, nothing can prevent the warm air of the room from escaping through it; and whenever this happens, there is not only an unnecessary loss of heat, but the warm air which leaves the room to go up the Chimney being replaced by cold air from without, the draughts of cold air... cannot fail to be produced in the room..."

"[A]s the smoke and hot vapour which rise from a fire naturally tend upwards, the proper place for the throat of the Chimney is... perpendicularly over the fire."

"But ...how far above the burning fuel... ought [the throat] to be placed."

"As the smoke and vapour which ascend from burning fuel rise in consequence of their being rarified by heat, and made lighter than the air of the surrounding atmosphere; and as the degree of their rarefaction, and consequently their tendency to rise, is in proportion to the intensity of their heat; and... as they are hotter near the fire than at a greater distance from it, it is clear that the nearer the throat of a Chimney is to the fire, the stronger will be... its draught, and the less danger there will be of its smoking."

"But on the other hand, when... this strong draught is occasioned by the throat of the Chimney being very near the fire... the draught... may become so strong, as to cause the fuel to be consumed too rapidly. There are likewise several other inconveniences which would attend the placing of the throat of a Chimney very near the burning fuel."

"[T]he height of the throat... will be determined by the height of the mantle. It can hardly be made lower than the mantle; and it ought always to be brought down as nearly upon the level with the bottom of it as possible."

"If the Chimney is apt to smoke, it will sometimes be necessary either to lower the mantle or to diminish the height of the opening of the Fire-place, by throwing over a flat arch, or putting in a straight piece of stone from one side of it to the other, or... building a wall of bricks, supported by a flat bar of iron, immediately under the mantle."

"Nothing is so effectual to prevent Chimnies from smoking as diminishing the opening of the Fire-place in the manner here described, and lowering and diminishing the throat of the Chimnney; and... a perfect cure may be effected by these means alone, even in the most desperate cases."

"[W]hen the construction of the Chimney is very bad... or... very unfavourable to the ascent of the smoke, and especially when both these disadvantages exist... it may... be necessary to diminish the opening of the Fire-place, and particularly to lower It, and also to lower the throat... more than might be wished: but... this can produce no inconveniences to be compared with that greatest of all plagues, a smoking Chimney."

"The position of the throat... being determined, the next points... are its size and form, and the manner in which it ought to be connected with the Fire-place below, and with the open canal of the Chimney above."

"Now the design of a Chimney Fire being... to warm a room... with the smallest expence of fuel... and... that... the air of the room be preserved... pure... fit for respiration, and free from smoke and... disagreeable smells."

"[H]eat which is generated in the combustion of the fuel exists under two... distinct... forms. One... is combined with the smoke, vapour, and heated air which rise from the burning fuel, and goes off with them into the... atmosphere; ...the other part, which appears to be uncombined, or... supposed, combined only with light, is sent off from the fire in rays in all possible directions."

"[I]t is... probable that the combined heat can only be communicated to other bodies by actual contact with the body with which it is combined; and... the rays... communicate or generate heat only when and where they are stopped or absorbed. ...[T]hey seem to bear a great resemblance to the solar rays. ...I must not enter too deeply into... the nature and properties of... radiant heat."

"What proportion does the radiant heat bear to the combined heat? ...[T]he quantity of heat which goes off combined with the smoke, vapour, and heated air is much more considerable, perhaps three or four times greater... And yet, small as the quantity is of... radiant heat, it is the only part... ever employed... in heating a room. The whole of the combined heat escapes by the Chimney, and is totally lost; and... no part of it could ever be brought into a room from an open Fire-place, without bringing along... the smoke..."

"There is, however, one method by which combined heat... may be made to assist in warming a room... by making it pass through something analogous to a German stove, placed in the Chimney above the fire."

"[A]s it is the radiant heat alone which can be employed in heating a room, it becomes an object of much importance to determine how the greatest quantity of it may be generated... and how the greatest proportion possible of that generated may be brought into the room."

"When the fire burns bright, much radiant heat will be sent off from it; but when it is smothered up, very little will be generated... and the combustion being very incomplete, a great part of the inflammable matter of the fuel being merely rarefied and driven up the Chimney without being inflamed, the fuel will be wasted... And hence it appears of how much importance it is, whether.. with a view to economy... cleanliness, comfort, and elegance, to pay due attention to the management of a Chimney Fire."

"Chimnies so often smoke when too large a quantity of fresh coals is put upon the fire. So many coals should never be put on the fire at once as to prevent the free passage of the flame between them. In short, a fire should never be smothered; and when proper attention is paid to the quantity of coals put on, there will be very little use for the poker; and this circumstance will contribute very much to cleanliness, and to the preservation of furniture."

"Now as the rays which are thrown off from burning fuel have this property in common with light, that they generate heat only when and where they are stopped or absorbed, and also in being capable of being reflected without generating heat at the surfaces of various bodies, the knowledge of these properties will enable us to take measures, with the utmost certainty, for producing the effect required... bringing as much radiant heat as possible into the room. This must be done, first, by causing as many as possible of the rays, as they are sent off from the fire in straight lines, to come directly into the room; which can only be effected by bringing the fire as far forward as possible, and leaving the opening of the Fire-place as wide and as high as can be done without inconvenience; and secondly, by making the sides and back of the fire-place of such form, and constructing them of such materials, as to cause the direct rays from the fire, which strike against them, to be sent into the room by reflection in the greatest abundance."

"[T]he best form for the vertical sides of a Fire-place, or the covings... is that of an upright plane, making an angle with the plane of the back of the Fire-place, of about 135 degrees.—According to the present construction of Chimnies this angle is 90 degrees... a right angle; but as... the two sides or covings of the Fire-place are parallel to each other, it is evident that they are very ill contrived for throwing into the room by reflection the rays..."

"As the object... is to bring radiant heat into the room... that material is best for the construction of a Fire-place which reflects the most, or which absorbs the least of it; for that heat which is absorbed cannot be reflected. ...[W]e have only to find out ...what bodies acquire least heat when exposed to the direct rays of a clear fire ...And hence it appears that iron, and ...metals off all kinds, which ...grow very hot when exposed to the rays ...are to be reckoned among the very worst materials ...to employ in the construction of Fire-places."

"The best materials... are fire-stone, and common bricks and mortar. Both... are, fortunately, very cheap..."

"When bricks are used they should be covered with a thin coating of plaster, which, when it is become perfectly dry, should be white-washed. The fire-stone should likewise be white-washed... and every part of the fire-place, which is not exposed to being foiled and made black by the smoke, should be kept as white and clean as possible. As white reflects more heat, as well as more light than any other colour, it ought always to be preferred for the inside of a Chimney Fire-place; and black, which reflects neither light nor heat, should be most avoided."

"[T]he quantity of radiant heat thrown into the room is diminished;—and it is easy to show that almost the whole of that absorbed by the metal is ultimately carried up the Chimney by the air, which, coming into contact with this hot metal, is heated and rarefied by it, and... goes off with the smoke; and as no current of air ever sets from any part of the opening of a Fire-place into the room, it is impossible to conceive how the heat existing in the metal composing any part of the apparatus of the Fire-place, and situated within its cavity, can come, or be brought into the room."

"This difficulty may be in part removed, by supposing... that the heated metal sends off in rays... even when it is not heated red hot; but still, as it never can be admitted that the heat, absorbed by the metal and afterwards thrown off by it in rays, is increased by this operation, nothing can be gained by it; and as much must necessarily be lost... to the air in contact with it, which... always makes its way up the Chimney, and flies off into the atmosphere, the loss of heat attending the use of it is too evident..."

"There is, however, in Chimney Fire-places... one essential part, the grate, which cannot well be made of any thing else but iron..."

"If it should be necessary to diminish the opening of a large Chimney in order to prevent its smoking, it is much more simple, œconomical, and better in all respects, to do this with marble, fire-stone, or even with bricks and mortar, than to make use of iron, which... is the very worst material... for that purpose; and as to registers, they not only are... unnecessary, where the throat of a Chimney is properly constructed, and of proper dimensions, but in that case would do mach harm. If they act It all, it must be by opposing their flat surfaces to the current of rising smoke in a manner which cannot fail to embarrass and impede its motion. But... the passage of the smoke through the throat of a Chimney ought to be facilitated as much as possible in order that it may be enabled to pass by a small aperture."

"Register-stoves have often been found to be of use, but because the great fault of all Fire-places constructed upon the common principles being the enormous dimensions of the throat of the Chimney, this fault has been in some measure corrected by them; but I will venture to affirm, that there never was a Fire-place so corrected that would not have been much more improved, and with infinitely less expence by the alterations here recommended..."

"All Chimney Fire-places, without exception... and even those which do not smoke, as well as those which do, may be greatly improved by making the alterations... here recommended; for it is by no means merely to prevent Chimnies from smoking that these improvements are recommended, but it is also to make them better in all respects... and when the alterations proposed are properly executed, which may very easily be done with the assistance of the following plain and simple directions, the Chimnies will never fail to answer... even beyond expectation. The room will be heated much more equally and more pleasantly with less than half the fuel used before, the fire will be more cheerful and more agreeable; and the general appearance of the Fire-place more neat and elegant, and the Chimney will never smoke."

"I know of no disadvantage... that attends the Fire-places constructed upon the principles here recommended."

"By the throat of a Chimney, I mean the lower extremity of its canal, where it unites with the upper part of its open Fire-place.—This throat is commonly found about a foot above the level of the lower part of the mantle, and it is sometimes contracted to a smaller size than the rest of the canal of the Chimney, and sometimes not."

"The breast of a Chimney is that part of it which is immediately behind the mantle.—It is the wall which forms the entrance from below into the throat of the Chimney in front, or towards the room. — It is opposite to the upper extremity of the back of the open Fire-place, and parallel to it;—in short it may be said to be the back part of the mantle itself."

"The width of the throat of Chimney... is taken from the breast of the Chimney to the back, and its length is taken at right angles to its width, or in a line parallel to the mantle..."

"The bringing forward of the fire into the room, or rather bringing it nearer to the front of the opening of the Fire-place;—and the diminishing of the throat of the Chimney, being two objects principally had in view in the alterations... here recommended... both... may be attained merely by bringing forward the back of the chimney."

"The only question... is, how far [the fire] should be brought forward?—The answer... bring it forward as far as possible, without diminishing too much the passage which must be left for the smoke."

"Now as this passage, which, in its narrowest part, I have called the throat of the Chimney, ought... to be immediately, or perpendicularly over the Fire, it is evident that the back of the Chimney must always be built perfectly upright.—To determine therefore the place for the new back, or how far precisely it ought to be brought forward, nothing more is necessary that to ascertain how wide the throat of the Chimney to be left, or what trace must be left between the top of the breast of the Chimney, where the upright canal of the Chimney begins, and the new back of the Fire-place carried up perpendicularly to that height."

"In the course of my numerous experiments upon Chimnies I have taken much pains to determine the width proper to be given to this passage, and I have found that, when the back of the Fire-place is of the proper width, the best width for the throat of the Chimney, when the Chimney and the Fire-place are of the usual form and size, is four inches. Three inches might sometime answer, especially where the Fire-place is very small, and the Chimney good, and well situated; but as it is... of much importance to prevent those accidents... putting too many coals at once upon the fire... when the throats of Chimnies were... very narrow..."

"It may... appear extraordinary... that Fire-places of such different sizes should all require the throat of the Chimney to be of the same width; but... the capacity of the throat of a Chimney does not depend on its width alone, but on its width and length taken together; and that in large Fire-places, the width of the back, and consequently the length of the throat of the Chimney, is greater than in those which are smaller..."

"In Fire-places as they are now commonly constructed, the back is of equal width with the opening of the Fire-place in front;-—but this... is faulty on two accounts.— First... the sides... or covings... are parallel to each other, and consequently ill-contrived to throw out into the room the heat they receive from the fire in the form of rays;—and secondly, the large open corners which are formed by making the back as wide as the opening of the Fire-place in front occasion eddies of wind, which frequently disturb the fire, and embarrass the smoke in its ascent in such a manner as often to bring it into the room."

"Both these defects may be entirely remedied by diminishing the width of the back of the Fire-place.—The width which, in most cases, it will be best to give it, is one third of the width of the opening of the Fire-place in front."

"It will frequently happen that the back of a Chimney must be made wider than... the rule here given... This may be, either to accommodate the Fire-place to a stove... already on hand... or for other reasons... with no considerable inconvenience.—It will always be best however to conform to it as far as circumstances will allow."

"Where a Chimney is designed for warming a room of a middling size, and where the thickness of the wall of the Chimney in front, measured from the front of the mantle to the breast of the Chimney, is nine inches, I should set off four inches more for the width of the throat of the Chimney, which supposing the back of the Chimney to be built upright, as it always ought to be, will give thirteen inches for the depth of the Flre-place measured upon the hearth, from the opening of the Fire-place in front, to the back.—In this case thirteen inches would be a good size for the width of the back; and three times thirteen inches, or thirty-nine inches, for the width of the opening of the Fire-place in front; and the angle made by the back of the Fire-place and the sides of it, or covings, would be just 135 degrees, which is the best position they can have for throwing heat into the room."

"I will suppose that in altering such a Chimney it is found necessary, in order to accommodate the Fire-place to a grate or stove already on hand, to make the Fire-place sixteen inches wide.—In that case, I should merely increase the width, of the back, to the dimensions required, without; altering the depth of the Chimney, or increasing the width of the opening of the Chimney in front.—The covings... would be somewhat reduced in their width... and their position... would be a little changed; but these alterations would produce no bad effects of any considerable consequence, and would be much less likely to injure the Fire-place..."

"Should the opening of the Chimney be too narrow, which however will very seldom be found to be the case, it will, in general, be advisable to let it remain as it is, and to accommodate the covings to it, rather than to attempt to increase its width, which would be attended with a good deal of trouble, and probably a considerable expence."

"[T]he points of the greatest importance... in altering Fire-places upon the principles here recommended, are, the bringing forward the back to its proper place, and making it of a proper width."

"[T]he new back... necessary to build in order to bring the fire sufficiently forward... need never be thicker than the width of a common brick.—I may say the same of the thickness necessary to be given to the new sides, or covings... or if the new back and covings are constructed of stone, one inch and three quarters, or two inches in thickness will be sufficient."

"Whether the new back and covings are constructed of stone, or... bricks, the space between them, and the old back and covings of the Chimney ought to be filled up... with loose rubbish, or pieces of broken bricks, or stones, provided the work be strengthened by a few layers or courses of bricks laid in mortar; but it will be indispensably necessary to finish the work where these new walls end... at the top of the throat of the Chimney, where it ends abruptly in the open canal of the Chimney by a horizontal course of bricks well secured with mortar."

"[W]here the throat of the Chimney has an end... where it enters into the lower part of the open canal of the Chimney, there the three walls which form the two covings and the back of the Fire-place all end abruptly. ...[T]hey should end in this manner for were they to be sloped outward and raised in such a manner as to swell out the upper extremity of the throat of the Chimney in the form of a trumpet, and increase it by degrees to the size of the canal of the Chimney, this manner of uniting the lower extremity of the canal of the Chimney with the throat would tend to assist the winds which may attempt to blow down the Chimney, in forcing their way through the throat, and throwing the smoke backward into the room; but when the throat of the Chimney ends abruptly, and the ends of the new walls form a flat horizontal surface, it will be much more difficult for any wind from above, to find, and force its way, through the narrow passage of the throat..."

"As the two walls which form the new covings... are not parallel... but inclined, presenting an oblique surface towards the front of the Chimney, and as they are built perfectly upright, and quite flat, from the hearth to the top of the throat, where they end... an horizontal section of the throat will not be an oblong square; but its deviation from that form is a matter of no consequence; and no attempts should ever be made, by twisting the covings above, where they approach the breast of the Chimney, to bring it to that form."

"All twists, bends, prominences, excavations, and other irregularities of form, in the covings... never fail to produce eddies in the current of air which is continually passing into, and through an open Fire-place in which a fire is burning;—and all such eddies disturb, either the fire, or the ascending current of smoke, or both; and not unfrequently cause the smoke to be thrown back into the room.—Hence... the covings... should never be made circular, or in the form of any other curve; but always quite flat."

"For the same reason, that is... to prevent eddies, the breast of the Chimney, which forms [the front] side of the throat... or nearest to the room, should be neatly cleaned off, and its surface made quite regular and smooth. This may easily be done by covering it with a coat of plaister, which may be made thicker or thinner in different parts as may be necessary in order to bring the breast of the Chimney to be of the proper form."

"[T]he form of the breast of the Chimney is... of... great importance... The worst form it can have is that of a vertical plane, or upright flat;—and next... worst... is an inclined plane.—Both... cause the current of warm air from the room, which will... sometimes find its way into the Chimney, to cross upon the current of smoke, which rises from the fire, in a manner, most likely to embarrass it in its ascent, and drive it back.— The inclined plane which is formed by a flat register placed in the throat of a Chimney produces the same effects; and this is one reason, among many... which have induced me to disapprove of register stoves."

"The current of air, which, passing under the mantle, gets into the Chimney, should be made gradually to bend its course upwards, by which means it will unite quietly with the ascending current of smoke, and will be less likely to check it, or force it back into the room.—Now this may be effected with the greatest ease and certainty, merely by rounding off the breast of the Chimney or back part of the mantle, instead of leaving it flat, or full of holes and corners; and this... ought always to be done."

"[T]he height to which the new back and covings ought to be carried... will depend not only on the height of the mantle, but also, and more especially, on the height of the breast of the Chimney, or of that part of the Chimney where the breast ends and the upright canal begins.—The back and covings must rise a few inches, five or six... higher than this part, otherwise the throat of the Chimney will not be properly formed;—but I know of no advantages that would be gained by carrying them up still higher."

"Those [grates] whose construction is the most simple, and... the cheapest, are beyond comparison the best, on all accounts.— Nothing being wanted in these Chimnies but merely a grate for containing the coal, and in which they will burn with a clear fire;—and all additional apparatus being, not only useless, but very pernicious, all complicated and expensive grates should be laid aside, and such as are more simple substituted in the room of them."

"And in the choice of a grate, as in every thing else, beauty and elegance may easily be united with the most perfect simplicity.—Indeed they are incompatible with every thing else."

"In modern built houses where the doors and windows are... made to close with such accuracy that no crevice is left for the passage of the air from without... When there is a fire burning... as the air necessary to supply the current up the Chimney where the fire burns cannot be had in sufficient quantities... through the very small crevices of the doors and windows, the air in the room becomes rarefied, not by heat, but by subtraction of that portion of air which is employed in keeping up the fire, or supporting the combustion of the fuel, and in consequence of this rarefaction, its elasticity is diminished, and being at last overcome by the pressure of the external air of the atmosphere, this external air rushes into the room by the only passage left for it... by the open Chimney."

"The most obvious remedy... is to provide for the supply of fresh air necessary for keeping up the fires by opening a passage for the external air into the room by a shorter road than down one of the Chimnies..."

"But Chimnies so circumstanced may very frequently be prevented from smoking even without opening any new passage for the external air, merely by diminishing the draught... up the Chimnies... by altering both Fire-places upon the principles recommended... in the foregoing..."

"Where the top of a Chimney is commanded by high buildings, by clifts, or by high grounds, it will frequently happen, in windy weather, that the eddies formed in the atmosphere by these obstacles will blow down the Chimney, and beat down the Smoke into the room.—This it is true will be much less likely to happen when the throat of the Chimney is contracted and properly formed than when it is left quite open, and the Fire-place badly constructed; but... One of the most simple contrivances that can be made use of, and which in most cases will be found to answer the purpose intended as well or better than more complicated machinery, is to cover the top of the Chimney with a hollow truncated pyramid or cone, the diameter of which above, or opening for the passage of the Smoke, is about 10 or 11 inches. ...[I]ts perpendicular height may be equal to the diameter of its opening above, and the diameter of its opening below equal to three times its height.-—It should be placed upon the top of the Chimney, and it may be contrived so as to make a handsome finish to the brickwork."

"The intention of this contrivance is that the winds and eddies which strike against the oblique surface of these covers may be reflected upwards instead of blowing down the Chimney.—The invention is by no means new, but it has not hitherto been often put in practice.—As often as I have seen it tried it has been found to be of use; I cannot say,. however, that I was ever obliged to have recourse to it, or to any similar contrivance; and if I forbear to enlarge upon the subject of these inventions, it is because I am persuaded that when Chimnies are properly constructed in the neighbourhood of the Fire-place little more will be necessary to be done at the top of the Chimney than to leave it open."

"In lighting a coal fire more wood should be employed than is commonly used, and fewer coals; and as soon as the fire burns bright, and the coals are well lighted, and not before, more coals should be added to increase the fire to its proper size."

"The enormous waste of fuel in London may be estimated by the vast dark cloud which continually hangs over this great metropolis, and frequently overshadows the whole country, far and wide; for this dense cloud is certainly composed almost entirely of unconsumed coal, which having stolen wings from the innumerable fires of this great city has escaped by the Chimnies, and continues to sail about in the air, till having lost the heat which gave it volatility, it falls in a dry shower of extremely fine black dust to the ground, obscuring the atmosphere in its descent, and frequently changing the brightest day into more than Egyptian darkness."

"I never view from a distance, as I come into town this black cloud which hangs over London without wishing to be able to compute the immense number of chaldrons of coals of which it is composed; for could this be ascertained, I am persuaded so striking a fact would awaken the curiosity, and excite the astonishment of all ranks of the inhabitants; and perhaps turn their minds to an object of economy to which they have hitherto paid little attention."

"Though the saving of fuel which will result from the improvements to the forms of Chimney Fire-places here recommended will be very considerable, yet I hope to be able to show in a future Essay, that still greater savings may be made, and more important advantages derived from the introduction of improvements I shall propose in Kitchen Fire-places."

"I hope likewise to be able to show in an Essay on Cottage Fire-places, which I am now preparing for publication, that three quarters, at least, of the fuel which cottagers now consume in cooking their victuals, and in warming their dwellings, may with great ease, and without any expensive apparatus, be saved."

"I was much flattered on my return to England, in September 1798... to find that the improvements in the construction of chimney fire-places, which I had recommended in my Fourth Essay, published... 1796, were coming into use... It has been objected... that they sometimes occasion dust and ashes to come into the room when the fire is stirred. I have examined several fire-places... that have... that fault; but... found... their imperfections have arisen from faults in... construction. Either the grate has been brought out too far into the room, or the opening of the fire-place in front has been left too wide—or too high—or the workman has neglected to lower and to round off the breast of the chimney—or... several of these faults... together..."

"When the throat of a chimney is situated very high up above the mantle, and especially when the mantle and breast of the chimney, or the wall that reposes on the mantle, are very thin, workmen who are employed to alter chimnies, setting about the work with their minds strongly prepossessed with what they consider as the leading principle... that the throat of the chimney should not be more than four inches wide, they are very apt to bring the grate too far forward. In dropping their plumb-line from the breast of the chimney, they do not reach up high enough into the chimney, but take a part of the breast, where it still goes on to slope backwards, for the bottom of the perpendicular canal of the chimney. They also very often commit another fault, not less essential... in neglecting to bring down the throat of the chimney nearer to the fire, when... too high."

"It is likewise very important to "round off the breast of the chimney;" though this... is very often intirely neglected... by workmen..."

"The breast of a chimney should always be rounded off... beginning from the very front of the lower part of the mantle, and ending at the narrowest part of the throat of the chimney, where the breast ends in the front part of the perpendicular canal of the chimney. If the under surface of the mantle is flat and wide, it will be impossible to round off the breast properly; and that circumstance alone renders it indispensably necessary, in those cases, to alter the mantle, or to run under it a thinner piece of stone, or a thin wall of bricks, supported on an iron bar, in order that the breast of the chimney may be brought to be of the proper form, and the throat of the chimney may be brought into its proper situation."

"If the under side of the mantle be left broad and flat... the cloud of dust or light ashes, that rises from a coal fire nearly burnt out, when... violently stirred... with a poker, striking perpendicularly against this flat part... must... be beat back into the room; but when the breast of the chimney is properly rounded off, the ascending cloud of dust and smoke more easily finds its way into the throat of the chimney, and is even directed and assisted in some measure by the warm air of the room that gets under the mantle and is going the same way."

"Another very common fault... in chimney fire-places, that have been altered on what have been called my principles, and which has a direct tendency to bring dust, and even smoke, into the room, is the sloping of the covings too much, and leaving the opening of the fire-place in front too wide. I have said, in my Essay on Chimney Fire-places, that where chimnies are well constructed, and well situated, and have never been apt to smoke, in altering them the covings may be placed at an angle of 135 degrees with the back; but... that they should never exceed that angle, and... bad consequences... must follow from making the opening of a fire-place very wide, when its depth is very shallow..."

"...for chimnies that are apt to smoke, the covings should be placed less obliquely in respect to the back, than in others that have not that fault. But most... workmen... paid little attention to these distinctions and... frequently... and sometimes in fire-places that have been remarkably shallow... the covings have been placed at an angle even more oblique than that above-mentioned."

"Another cause... in bringing dust and smoke into rooms... is the great nicety with which the doors and windows are fitted in their frames, which prevents a sufficient quantity of fresh air from coming into the room, to supply a brisk current up the chimney. ...[A]ll the alterations in fire-places on the common construction, that have been recommended in order to improve them, must tend directly and very powerfully to lessen this evil; but nothing will so completely remedy it as lowering the mantle, and diminishing the width of the fire-place."

"How many fire-places in close rooms have been cured completely of throwing puffs of smoke and dust into the room, merely by placing a register-stove in them? But there is surely nothing peculiar to a register-stove that could enable it to perform such a cure, but merely as it serves to diminish the width and heighth of the opening of the fire-place; and how much easier could this be done with marble, or other stone, or with bricks and mortar... [T]he openings of chimney fire-places are in general certainly too wide and too high and... there is no way of reducing them to a proper size... so cheap, or more effectual..."

"[C]ovings of... fire-places must be placed obliquely, and they must not be constructed of metal; and if the sides and back of the grate be constructed of fire bricks instead of iron, the fire will burn still brighter, and will fend off considerably more radiant heat into the room."

"If in constructing or altering chimney fire-places, the rules laid down in my Essay on that subject are stricty adhered to, chimnies so fitted up will very seldom be found either to smoke, or to throw out dust into the room; and should they be found to have either of these faults, there is a remedy for the evil, as effectual, as it is simple and obvious: Bring down the mantle, and the throat of the chimney lower; and if it should be found necessary, reduce the width of opening of the fire-place in fronts and diminish the obliquity of the covings."

"I am not the inventor of any of those stoves or grates, that have been offered to the public for sale, under my name."

"In building a house an air canal, about twelve or fifteen inches square, in the clear, and open at both ends, may be constructed, in, or near the center of each stack of chimneys; and two branches from this air canal, both furnished with registers, may open... one... into the fire-place, just under the grate, and the other over the fire-place, and near the top of the room, or just under the ceiling... The bottom of this air tube should reach to the ground, where it should communicate freely with the open air of the atmosphere..."

"Those who consider what an immense quantity of air is required to supply the current that sets up the chimney of an open fire place, where there is a fire burning, must perceive what an enormous loss of heat there must be, when all this expence of air is supplied by the warmed air of the room, and that all this warmed air is necessarily and constantly replaced by the cold air from without, which finds its way into the room, by the crevices of the doors and windows. But all this waste of heat, or any part... may be prevented by the scheme proposed, for if the air necessary to the combustion of the fuel, and to the supplying of the current up the chimney, be furnished by the air-tube, the warmed air in the room will remain in its places and as this will in a great measure prevent the cold currents from the crevices of the door and windows, the heat in the room will be the more equable, and consequently the more wholesome and agreeable on that account."

"[B]y a proper use of the two registers, together with a judicious management of the fire, the air in the room may either be made hotter, or colder;—or may be kept at any given temperature—or the room may be most effectually ventilated; and that this change of air may be effected, either gradually or more suddenly."

"[W]e must never forget that it is the room that heats the air, and not the air that heats the room."

"The rays that are sent off from the burning fuel, generate heat, only when and where they are stopped, or absorbed, consequently they generate no heat in the air in the room, in passing through it, because they pass through it, and are not stopped by it, but, striking against the walls of the room, or against any solid body in the room, these rays are there stopped and absorbed, and it is there that the heat found in the room is generated. The air in the room is afterwards heated by coming into contact with these solid bodies. Many capital mistakes have arisen from inattention to this most important fact."

"It is really astonishing how little attention is paid to events which happen frequently, however interesting they may be as objects of curious investigation, or however they may be connected with the comforts and enjoyments of life."

"Things near us, and which are familiar to us, are seldom objects of our meditations."

"How few persons are there who ever took the trouble to bestow a thought on the subject in question, though it is, in the highest degree, curious and interesting."

"It has frequently been a subject of inquiry, whether the ancients were acquainted with chimneys, or open fire-places. In the houses discovered at and , there are no chimneys; they all appear to have been warmed by furnaces and flues."

"[T]hough one or more expressions of ancient authors may appear to allude to a chimney, if the ancients were acquainted with the art of constructing, in mason-work, elevated funnels for conveying away the smoke, it must be allowed, when we consider the many proofs... to the contrary, that they were... extremely rare."

"It is not known at what time chimneys began to be used. The writers of the 14th century seem either to have been unacquainted with chimneys, or to have considered them as the newest invention of luxury."

"That there were no chimneys in the 10th, 12th, and 13th centuries, has been presumed from the terms "ignitegium" [curfew] or "inpritegium" the curfew-bell of the English, and couvrefeu of the French; which seem to intimate, that the people made fires in their houses in a hole or pit in the centre of the floor, under an opening formed in the roof; and when the fire was burned out, or the family went to bed at night, the hole was shut by a cover of wood."

"The oldest certain account of chimneys, is in the year 1347. An inscription at Venice, records... a great many chimneys (molti comini) were thrown down by an earthquake."

"The first chimney-sweepers in Germany came from , , and the neighbouring territories; and these for a long time were the only countries where the cleaning of chimneys was followed as a trade. Hence it is conjectured, that chimneys were invented in Italy."

"[I]n the countries of modern Europe, the use of stoves prevail throughout the north; while in France and Great Britain, open fires are used. In the warm countries of Italy and Spain, there are very few chimneys, and the only method usually practised of tempering the cold, which is sometimes severely felt, is to burn charcoal in portable brasiers."

"A consists of a fire-place, in which the fuel is consumed, and a flue to carry off the smoke and vapour arising from the combustion; thus affording the benefit of the heat of a fire without the inconvenience of its smoke. But these objects were, and still are, very imperfectly attained; a large portion of the fuel being wasted without increasing the warmth of the apartment."

"Dr. Franklin, in 1785, published "Observations on the Cause and Cure of Smoky Chimneys." He has very satisfactorily explained all the usual causes of this defect, and shown their remedies. To this pamphlet succeeded the "Essay" of Count Rumford, in 1796, whose improvements in the construction of fire-places have been very generally adopted. These two works together, form a valuable body of information. They are well known to the public, but it is not so generally known, that exactly a hundred years ago, viz. in the year 1715, Dr. Desagulier published his book, entitled "Fires Improved, being a new method of Building Chimneys, so as to prevent their smoking, &c." which is a translation of a still older work from the French of M. Gauger, which shows that the most, if not all, the principles pointed out by Count Rumford were understood, and are explained by M. Gauger. He also proposed seven different constructions of chimneys, in which there are hollow cavities made by iron plates in the back[,] jambs and hearth, through which plates the heat passing warms the air in those cavities, which is continually coming into the room fresh and warm. This construction had many obvious advantages; but the expense and difficulty attending it, at that early period, discouraged the propagation of the invention. In our own times, however, similar constructions have been brought forward as new, probably without the knowledge of what had been done so long before, and therefore with all the merit of invention."

"[H]aving, in 1742, invented an open stove for the better warming of rooms, and at the same time saving fuel, as the fresh air admitted was warmed in entering, I made a present of the model to Mr. , one of my early friends, who having an iron furnace, found the casting of the plates for these stoves a profitable thing, as they were growing in demand. To promote that demand, I wrote and published a pamphlet, entitled, "An Account of the new-invented Pennsylvania Fire Places; wherein their construction and manner of operation is particularly explained, their advantages above every method of warming rooms demonstrated; and all objections that have been raised against the use of them, answered and obviated, &c." This pamphlet had a good effect; governor Thomas was so pleased with the construction of this stove as described in it, that he offered to give me a patent for the sole vending of them for a term of years; but I declined it, from a principle which has ever weighed with me on such occasions, viz: That as we enjoy great advantages from the inventions of others, we should be glad of an opportunity to serve others by any invention of ours; and this we should do freely and generously."

"An ironmonger in London, however, assuming a good deal of my pamphlet, and working it up into his own, making some small changes in the machine, which rather hurt its operation, got a patent for it there, and made, as I was told, a little fortune by it. And this is not the only instance of patents taken out of my inventions by others, though not always with the same success; which I never contested, as having no desire of profiting by patents myself, and hating disputes."

"The use of these fire places in very many houses, both here in Pennsylvania, and the neighbouring states, has been, and is, a great saving of wood to the inhabitants."

"[O]f the [15 1/2] millions of tons of coals raised yearly from the mines, not more than [3 1/2] millions are consumed by steam-engines and in manufacturing operations, leaving [11] or [12] millions of tons of fuel to be mismanaged in kitchens and sitting-rooms throughout the country."

"The register-plate was described at the close of the fifteenth century by Alberti... and by others who wrote afterwards. Were this simple and cheap smoke-valve introduced into every cottage chimney, it would save the heat of [5] or [6] millions of tons of coals that is now annually wasted and thrown away."

"Vitruvius... thus describes the construction of the or stove for heating the or sweating room of a bath. The floor is made inclining, so that a ball placed on any part of it would roll towards the fireplace, by which means the heat is more equally diffused in the sweating-chamber. The floor is paved with tiles... and on these are built brick pillars... two feet high, and cemented with clay and hair mixed together. The pillars are placed at such a distance, as will allow tiles to be laid on them to form the ceiling of the hypocaust, and support the pavement of the caldarium. The air to the caldarium, or room over the hypocaust, is admitted through an aperture in the centre of its roof, from which a brazen shield is suspended by chains. By raising and lowering this shield, which opens or shuts the aperture, the heat of the caldarium is regulated. For heating the water to supply the baths, there are to be three caldrons... the arched cavities in which they stand are to be heated by one fire. After such minute instructions how to form the stove in which large quantities of wood were to be consumed, it is singular that he should omit to notice in what way the smoke produced was to be conveyed into the atmosphere. From this silence, it has been inferred that he was ignorant of what Anderson calls "the elegant and commodious tube now known by the name of a chimney.""

"Longlande, in Pierce the Plowman'sVision, feelingly alludes to the change as prompted by a mean and selfish wish to abridge the ancient hospitality observed towards the poor. "Elynge is that halle eche day in the wyke, Ther the lorde ne the lady liketh nat to sitte. Nowe hath eche ryche a reule to eten by hym silve In a privey parlour for pore mennys sake; Or in a chaumbre wyth a chymney, and leve the cheef halle That was mad for melis men to eten inne." The chimneyed chamber was spacious and lofty, and usually formed with a large bay window, looking into the court of the castle."

"The strong hold of Conway is further remarkable for exhibiting another domestic refinement, not found, except at , in any contemporary building. A hearth is recessed into the wall, and has a rising from it for the passage of the smoke into the air. It is true, that after this period, flued fireplaces were sometimes made in rooms that had been erected without them, but the chimney in Conway Castle, and a similar one at Kenilworth [Castle], appear as if they had formed part of the original edifices."

"Leland, in his Itinerary... gives an account of his visit to . ...[H]e says, ..."One thynge I muche notyd in the hawle of Bolton, how chimeneys were conyened by tunnells made on the syds of the walls betwyxt the lights in the hawle, and by this means, and by no covers, is the smoke of the harthe in the hawle wondor strangely conveyed.""

"[P]revious to the erection of this stronghold, the word chimeney is of frequent occurrence. Chaucer in several places speaks of chambers with chimeneys; Longlande we have seen also employs it: and Wiclif, in his translation of the New Testament, in 1380, has the expression, "thei schulen send him into the chymeney of fier." In the poetical vocabulary, "chimeney" appears to be synonymous with "fireplace," or "hearth recess;" and the verbal equivalent to the word in the reformer's Testament is "furnace." Leland, who wrote a century after, in using the word almost defines it. "The chimeneys were conveyed by tunnels;" or, in other words, the fireplace was continued by a tunnel to the top of the building; a description that will accurately fix the meaning of the word when found in writers previous to the Tudor period; for it is quite obvious the chimneys in common use, and with which Leland was acquainted, had no tunnels to convey the smoke from the hearth... His observation, that the smoke from the hearth was not conveyed by "covers," also shows that at the time... covers were common appendages to fireplaces for conveying smoke. What these were, must be guessed... most likely... "canopies" or "pyramids " constructed over a hearth where it was not recessed into the wall, and often also where it was. Underneath this canopy was a hole through the wall for the escape of the smoke..."

"It is hoped that these amusing details will not make the book less interesting to those who seek to become acquainted with the beautiful laws on which warming and ventilation depend; the principle of the latter art being, in fact, identical with that by which nature ventilates our globe—a hot ascending current from the warm regions, while the cooler air streams in at a lower level from the temperate regions."

"[A] great improvement was made in France in fire-places by Louis Savot (born 1579 ; died 1640), a licentiate in the Faculty of Medicine at Paris."

"Savot pointed out the means for curing that domestic plague—a smoky chimney; and, like a true physician, set about investigating the causes of the disease."

"He saw the evils of large chimneys, and the necessity for a due supply of air to the fire. The fire should be proportioned to the size of the chimney, and vice versâ, and smoke may often be prevented by lowering the mantel."

"[Savot] also points out how the chimney may be too long for the fire, or how one large chimney may draw upon another smaller one; and he recommends that the flue be smooth on the inside, to diminish friction."

"To improve the draught of the fire he raised the hearth about 4 inches, and lowered the mantel so as to make the opening of the fire-place about 3 feet high."

"The width between the jambs was reduced to 3 feet; the jambs from the mantel were to be carried up sloping to the waist, or where the flue begins to be of uniform width, and the opening of the fire-place was formed like an arch."

"But, where the fire-place could not be conveniently altered, Savot perforated with small holes a plate of iron, the width and length of which were nearly equal to the hearth, and this was fixed 3 inches above the tiles of the common hearth. On this perforated plate he placed & grill de fer of the same length as the billets to be burned, and raised 9 inches above the plate; the wood was placed on the grate, the charcoal on the perforated plate, and the hearth received the ashes; the air, rising through the small holes, made the charcoal burn briskly, and this so much assisted the burning of the wood, that a rapid draught up the chimney was established, and smoke prevented."

"In Savot's description of the fire-place used to heat the Cabinet des Livres, at the , we have the first recorded attempt at combining the cheerfulness of an open fire with the economy of an enclosed stove. Fig. 15 is a front view, and Fig. 16 a vertical section of this ingenious contrivance."

"The hearth was a thick iron plate placed above the old hearth, with an interval, n, of 3 inches between them. The two sides, or covings of the fire-place, were also formed of thick iron plates, placed 3 inches from the jambs. The space, n, at the back, and the spaces at the sides, communicated with the space, n, under the hearth ; two pipes, or channels, i, communicating with these hollow spaces, opened into the room at c, as shown by the dotted line in the section; these spaces could be closed at pleasure. When the fire was burning, the iron hearth, and the plates which formed the sides or covings, and the back, became very hot. The cold air at the floor, entering by the openings at a, into the space, n, was heated by the hearth, and rising into the spaces at the back and sides, had its temperature further increased; it then entered the channels, i, and escaped at c, thus diffusing an agreeable warmth over the whole room."

"In 1678, Prince Rupert invented a fire-place, so contrived that the draught took a downward direction before entering the flue, as shown in Fig. 18, in which... x is a wall built at a distance of 10 inches from the back of the hearth recess, and carried up to the mantel, where it is terminated by the wall x, thus completely closing all communication between the flue and the room. An opening, a, is made in this wall, 10 inches high, and of the same width as the length of the grate, and its sill is 2 inches above the top rib of the grate. Fixed within the chimney is a plate of iron, i, placed perpendicularly, so as to divide it into two equal parts. To the upper edge of this plate is hinged an iron door, c, as long as the chimney is wide, and this door can be brought into the position c, or into that indicated by the dotted lines at e. The fuel grate stands on the hearth, and is placed nearly in a line with the wall of the room. At the back of the ash-pit is a brick that closes the aperture through which the soot is removed. When the fire is first lighted, the smoke door, c, is pushed back, and when the draught is once established, this door is drawn forward, and the smoke being thus prevented from flowing upwards, reverberates downwards, and passes the lower edge of the division plate, i, and rises between it and the back of the hearth into the chimney flue. In boisterous weather, or with such a fire-place, in an upper room, where the chimney is short, another iron door, r, is hung under the edge of the mantel, in front of the fire-place, and extending the whole width of the opening. Its breadth varies according to circumstances, but it is made so as to reach within 2 inches of the upper bar of the fire-grate, when hanging in the position shown by the dotted lines at s. This converts the fire into a furnace, and the room will, in such case, be "warmer than it would be with a fire four times the size made in a common cradell." When the smoke flows regularly through the aperture, a, this door is thrown back out of use, as at r. In some cases, the ordinary fire-board or fire-cloth was used instead of this door."

"An economical method of heating two rooms by one ...[fireplace] is described by Savot. A plate of iron is made to separate the fire-places of the two adjacent rooms. A fire made on the hearth, a, (Fig. 20), heats the plate, n, and this, in its turn, by its radiation, warms the air in the adjacent room, e, as effectually as a stove would do, provided its flue, i, is properly closed. Or if the second room have no chimney, it may... be warmed by making an opening in the wall... and closing it with an iron plate. When Dr. Franklin was in Paris, he saw an example of this contrivance, and estimated it highly."

"[T]here is one writer, whose inventions have especially served as the type of many a modern fire-place, and at the time of their introduction in 1713, showed a great and sudden advance in the art of warming apartments. It has been said... that the author... was no less a man than the Cardinal Polignac, who, under the assumed name of Gauger, published a treatise, entitled "La Mechanique du Feu, ou l'Art d'en augmenter les effets et d'en diminuer la dépense, contenant le Traité de Nouvelles Cheminées qui echauffent plus que les Cheminées ordinaires, et qui ne sont point sujettes à fumer" [The Mechanics of Fire, or the Art of increasing its effects and reducing its expenditure, containing the Treatise on New Chimneys which heat much more than ordinary Chimneys, and which are not subject to smoking] This treatise was reprinted at Amsterdam in 1714, and a translation of it, by Dr. Desaguliers... was published in London in 1716."

"It is remarkable that, while the open fireplace was one of the earliest contrivances invented to contribute to the health and comfort of man, the upright flue for carrying off the injurious products of combustion should have remained one of the latest."

"Cold air, being heavier than warm, will fall below the latter, and press it upwards to make way for itself. Thus the air in the neighborhood of the fireplace will press the hot smoke up into the chimney-throat. If this throat is only large enough to take the smoke, hot air only will enter the flue, and the draught will be rapid. But if the throat is larger than necessary, that part of the cool air of the room which enters the fireplace and becomes most heated by the fire, and next in buoyancy to the smoke, will, in its turn, be pressed up by the cooler air behind it, and enter the flue alongside of the smoke. Indeed, the entire volume of the air of the room, being warmer than the outside air, will tend to enter the flue with the smoke, so long as there be room provided for its entrance. The heat of the column, and consequently the rapidity of its rise, will therefore be proportionately diminished."

"For this reason the throat of the chimney should be contracted until it is no larger than is sufficient to carry off the products of combustion. A similar contraction throughout the entire length of the flue would be desirable, were it not that an allowance must be made for clogging up by soot, and for the resistance by friction to the passage of the air offered by the rough walls of the flue."

"The first, to recognize and apply this principle was Count Rumford (1796-1802). ...But he is to be blamed for not investigating or at least acknowledging the progress made by his predecessors in this particular. ...[H]owever much good he may have done in improving the form of the chimney-throat, and in calling public attention to the advantages of bevelled over rectangular jambs, he... also did much to discourage any further effort in economizing the waste heat of the smoke, and should therefore be considered as having really done more than any other one man to retard the proper development of the subject."

"[Rumford] complains of the enormous waste of heat, and regrets that no means of saving it can be invented, in the face of the discoveries of both [Louis] Savot and [Nicholas] Gauger. Even his bevelled jambs for better reflecting the rays into the room had long since been recommended by Gauger. They were brought forward as quite new by Rumford. ...In speaking of the waste in unconsumed smoke... [Rumford] gives no way of consuming the smoke, or of alleviating the evil."

"[T]he so-called Rumford stove or fireplace... contracted the area of the fire-chamber, and gave the sides an angle of 135° with the back, or, which is the same thing, of 45° with the front of the fireplace, in order, as he said, to reflect the greatest possible amount of heat into the room. He considered the best proportions for the chimney recess to be when the width of the back was equal to the depth from front to back, and the width of the front or opening between the jambs three times the width of the back. These proportions are used today, and are undoubtedly the best. He objected to the use of iron for these surfaces on account of its great heat-conducting power, which wasted the heat and cooled off the fire; but advocated some non-conducting substance, such as fire-clay. He also objected to circular covings, on the ground that they produced eddies or currents, which would be likely to cause the chimney to smoke."

"But [Rumford's] chief, or perhaps only, real improvement consisted in the reduction of the size of the chimney-throat, and the rounding off of the lower edge of the chimney-breast... to afford less obstruction to the ascent of the smoke. ...This form, as given by Rumford, is, however, still defective. The smallest part of the flue should be at the bottom... so as to prevent the entrance into the flue of unburnt air from the room. ...The back of the fireplace should also incline forwards, as shown, in order to increase its radiating effect..."

"The simple and earnest style of Count Rumford's essays, the substantial nature of his acknowledged improvement, the facility with which it could be tested, and the enthusiasm with which he urges its importance, the detailed directions he gives for the guidance of the builder, and the liberality with which he offered the free use of his invention and services to the public,—all tended to make a permanent impression, and not only to give the precedence over all others, but even to place the latter altogether in the shade. So much [so] that, though infinitely more important as tending to improve the ventilation of the apartment and the draught of chimney, as well as to save the waste heat of the fuel, they were almost forgotten, and, so far as the mass of the public is concerned, remain so... to the present..."

"So great was the influence of Count Rumford as a man of science, and his ability as a writer, that his failure to acknowledge the value of the efforts of his predecessors seemed like a tacit condemnation of them, and proved the severest blow to the cause."

"Mr. Culin read a communication from Mr. Charles Laubach, of Riegelsville, Bucks Co., Pa., giving an account of the stove plates manufactured at Durham Furnace, Durham, Pa., from 1741 to 1789."

"Iron stoves were unknown before 1678, when Prince Rupert, of England, attempted to convert a fireplace into a furnace. This was the first attempt to force smoke back over the fire and create heat for warming apartments by the aid of iron."

"[A]bout 1710, Count Polignac, of France, made an attempt to convert an ordinary fireplace into a heating apparatus by simply constructing a fireplace with an iron back, hearth, and jambs. The result was only a slight saving of heat. In 1716 Dr. Desaguliers, of London, succeeded in improving the Polignac fireplace so that it could be used for burning coal."

"The first attempt at manufacturing heating apparatus at Durham, Pa., was in 1741, by the Durham Furnace Company. The firm consisted of George Taylor (later one of the signers of the Declaration of Independence), James Logan and James Morgan, iron masters (the latter being the father of General , the hero of Cowpens)."

"In 1745 Franklin invented the famous stove which bears his name. This pattern continued to be cast at the Durham Furnace until 1774, and probably later."

"The object of the art of heating is to secure this required warmth with the greatest economy and efficiency. ...For reasons of health it may be assumed that no system of heating is advisable which does not provide for a constant renewal of the air in the locality warmed, and on this account there is a difficulty in treating as separate... the subjects of heating and ventilation... The object of all heating apparatus is the transference of heat from the fire to the various parts of the building it is intended to warm, and this transfer may be effected by , by conduction or by . An open fire acts by radiation; it warms the air in a room by first warming the walls, floor, ceiling and articles... and these in turn warm the air. Therefore... the air is... less heated than the walls. In many forms of fireplaces fresh air is brought in and passed around the back and sides of the stove before being admitted into the room."

"The open grate still holds favour... though... it has been superseded by the closed stove. The old form of open fire is... wasteful of fuel, and the loss of heat up the chimney and by conduction into the brickwork backing of the stove is considerable. Great improvements, however, have been effected in the design of open fireplaces, and many ingenious contrivances... are now in the market..."

"Unless suitable fresh air inlets are provided, this form of stove will cause the room to be draughty, the strong current of warm air up the flue drawing cold air in through the crevices in the doors and windows. The best form of open fireplace is the ventilating stove, in which fresh air is passed around the back and sides of the stove before being admitted through convenient openings into the room. This has immense advantages over the ordinary type of fireplace. The illustrations show two forms of ventilating fireplace..."

"The years of the central- fireplace brought the development of the first s. ...Metal andirons in their functional form consisted of two vertical bars on flat or arched leg bases, with an elevated horizonal cross-brace to space them apart and keep them upright. ...The upper part of the vertical members featured extended prongs or notches. This gave support for a horizontal rod, or spit, for cooking meat, and... hanging cooking pots directly over the fire."

"The first wall fireplaces were constructed without chimneys. They used an extended masonry or metal hood over the fire. Smoke exited through a simple hole through the wall... Early fireplaces... had no sides or other devices to form a firebox. ...Many fireplaces of the wall type were located in a corner of a room."

"[C]rude efforts were eventually adopted to create s of s to channel the unwanted smoke... The masonry surface behind the fire aided... radiating heat, and the heavy mass... in the wall and the chimney stored heat... increasing its efficiency."

"Early experiments... led to a method to create firebrick... for... the... firebox. ...s were made more tight with the emergence of fired-clay pipe or flue liners."

"Experiments by, and the design work of... led to the type of fireplace closest to the present day configuration. ...The designs Thompson perfected were known as Count Rumford Fireplaces."

"Many homeowners abandoned the fireplace as a means of cooking with the emergence of the eighteenth century manufactured stoves. Led by the development of... the ', other types of cast iron stoves became available, including the potbelly stove and the massive kitchen range. The advantages offered by the stoves included radiation from the heated cast iron surfaces, better draft for more efficient burning, and successful operable dampers to regulate the fire."

"Our present century has seen the development, manufacture, and widespread use of double-walled steel heat-circulating fireplace unit."

"The desire for safe, efficient fireplace units led designers and engineers to develop the factory-built, so-called zero clearance fireplace unit."

"Fireplaces have... come a long way from their crude "open fire" origins to... safe, efficient units... The heavy masonry materials... are no longer necessary. The amount of space required has been dramatically reduced, and the amount of labor... as well. ...Current fireplaces provide the inherent "charm"... while serving as an efficient and usable source of heat."

"Cooling by evaporation of water or by fans and warming by heaters and fireplaces are artificial aids... From a practical, economic, or aesthetic point of view it makes much more sense to develop, where possible, constructional features for warming or cooling the owner-built home."

"The design of a house around its massive, central fireplace has... always felt right to this writer-builder."

"The fireplace designed and built by the author... is unobstructed, free-standing, and insistent, at the same time that it is supportive of the roof. It is central to the room... as it stands sunken, in its fire pit. ...[W]here the massive stone chimney rises to pierce the roof, a translucent band cascades filtered, mellow illumination [from integrated skylights] down the stone face."

"Unfortunately, most of the technical improvements in fireplace design have not yet emerged into common usage... in spite of the fact that improvements occurred as far back as 1624, when Louis Savot invented the first heat-circulating fireplace. His unit... became the prototype for Ben Franklin's 1742 Pennsylvania stove. The 1624 French fireplace achieved 30 to 45 percent more efficiency than... most American tract-home fireplaces today!"

"Few people are aware that practically all of the technical features of Franklin's... stove were copied from earlier inventors. [Louis] Savot's concept of a preheated draft was employed by Franklin... Prince Rupert's descending flue, invented in 1687, was also applied... The smoke rose in front of a hollow metal back, passing over the top and down the opposite side. ...Ducts similar to those invented by Nicholas Gauger, in 1716, were also incorporated in the Franklin stove."

"The most noteworthy development of the open fireplace took place in 1796, when... Count Rumford published... "Chimney Fireplaces." His main contribution was the alleviation of the smoking chimney. One fault... he... asserted, was due to the large chimney throat. Rumford also introduced the inclined fireback, which increased fireplace effeciency by providing... greater . For the purpose of breaking up the current of smoke in the... downdraft, the back smoke shelf of Rumford's improved fireplace ended abruptly—a practice strictly adhered to... to this day."

"It is more important for the owner-builder to understand the aerodynamics of combustion and ventilation than... detailed specifications for one particular fireplace..."

"[T]he operation of a standard fireplace will effect the displacement of over twice the amount room air required for optimum ventalation. Half the amount... should therefore, be drawn from outside... pass only indirectly through the building, and be prevented from immediate escape through the fireplace."

"Fireplace installation in... efficiently weather-stripped houses creates a problem of... sufficient air for chimney draft. A partial vacuum... is the result, tending to pull smoke and combustion gases... into the room."

"Air-intake control is the key to efficient fireplace combustion. The ignition of a correctly proportioned gas-air mixture will promote... complete combustion... and emit "clean" gases... carbon dioxide, water vapor, oxygen, and nitrogen."

"When smoke and soot are... coming out of a chimney... combustion is incomplete."

"[F]oot-chilling floor draft was... solved by Savot through... a subfloor inlet return for previously heated air. ...[T]his ...would eliminate ...trouble frequently encountered in modern homes ..."

"The owner-builder, desirous of eliminating foot-chilling floor drafts, should... consider... a sunken hearth... and there is less danger of flying sparks..."

"Count Rumford was the first to extensively study inside-fireplace proportions. ...Deep-set fuel beds produce more smoke... since there is scant combustible air at the back... [T]he rate of smoke emission increases proportionally to the depth of the firebox, especially in the early stages of firing."

"Count Rumford's conclusions about the relationship between the chimney throat and effective draft have yet to be scientifically questioned. The throat opening should... constrain the effluent, so that it will be forced to... a speed high enough to discourage down drafts."

"A groundbreaking advance on the way to efficient structures in steel construction was the principle of using tetrahedra as a basic module instead of rectangular geometries. The inventor is considered to be the all-round genius Alexander Graham Bell, who became famous for the invention of the telephone and who built kites that were big enough to lift people into the air. Another engineering genius was Vladimir Grgorevic Suchov, whose genius can definitely be compared to Gustav Eiffel. In 1919 he designed towers up to 350 m high on the principle of hyperbolic paraboloids. The lightness of his constructions is seldom achieved even today, in Moscow there is a television tower with a height of 160 m. His tent constructions with suspended steel grids can be seen as the forerunners of the Olympic roof in Munich or the new Center Pompidou Metz. In , Suchov realized the first double-curved lattice shells on the floor plan of rectangular halls as early as the 19th century. Most of the structures still in existence are massively endangered by corrosion and destruction; current rescue operations are trying to preserve this legacy."

"Shukhov's water tower['s]... double curved surface... was generated by a mesh of straight members overlapping in contrary directions... supported by horizontal rings. While... constructed from steel... Shukhov's 1896 patent application... initially mentions straight wooden beams as a material option. ...[T]he ...application describes ...being able to resist extreme forces while using very little material. As a result, Shukhov's... design was used extensively throughout Russia in the first half of the twentieth century."

"The theory of minimal surfaces and surfaces of constant mean curvature is a vigorously developing branch of mathematics which has a broad range of applications in physics, chemistry and biology where it investigates, for example, soap films and bubbles, bimaterial interfaces or capillaries. Over the past decades, it was also boosted by the anticipated nanotechnology applications. Applications of minimal surfaces have been extensively explored in the sculpture (see e.g. the works by ) and in architecture (s, the Shukhov radio tower ... works by etc.) The first mention of minimal surfaces goes back to Lagrange (1798), who considered the... variational problem..."

"Construction history teaches us that excellent, huge structures like this one are invariably the result of a specific and singular solution, in which all aspects were reflected upon before or after early experiences in the building sequence. The author wants to compare the achievement of Segovia Aqueduct with more recent singular structures: the Oka electricity pylons (1929) by... Vladimir Gregoryevich Shukhov... and the roof of the 1972 Olympic Games in Munich, by a team directed by Gunter Behnish, , /, and Jürgen Linkwitz..."

"The structures of the great Russian engineer Vladimir Grigor'evič Šuchov (Shukhov) are among the world's most sophisticated and distinctive in the history of steel construction. These extremely stable structures, such as cable-stabilised arches, doubly curved grid-shells and above all lattice towers hold a great fascination... They result from the desire to achieve an engineering objective using as little material as possible. ...[T]hey are a testament to the extraordinary creativity and inventiveness of an extensively educated engineer ..."

"Many engineering structures of today were anticipated in Shukhov's works. Some of his others have no modern equivalent or have remained unmatched in their visual impact and... technical efficiency. Among these are... the lattice towers... Countless towers with this new type of construction and geometries defined by just a few parameters were built [by him]... The fine-lined tower structures served as water towers, lighthouses, power transmission masts and fire brigade watchtowers—with some of them still in use today"

"Matthias Beckh analyzes these hyperbolic lattice towers... [and] demonstrates how... Shukhov was already parameterizing his structures as part of the design... Modern methods... provide... Beckh with the tools to place Shukhov's achievements in a historical context and validate their considerable contribution to the history of . He also...demonstrate[s] their relevance to modern structures. ...Beckh was part of the first research project into Shukhov's structures ...The research project ...included in-depth studies of building history ...and detailed investigations into the way the structures were built. Later investigations were intended to provide ...knowledge about the load assumptions... also... relevant to modern structures."

"The object of this book is gain deeper knowledge on the architectural history of hyperbolic structures. The focus of the investigation is the first hyperbolic lattice towers ever built, the work of... Shukhov."

"This form of construction, which had no predecessors... is notable for its strength and economy of materials. Added to this is the high visual impact..."

"Even today, Shukhov's load-bearing system can be found in one form or another in architecture..."

"This book presents the results of the first ever extensive analysis of the way these structures work."

"The of a one-sheeted hyperboloid is resolved into three different mesh variants to create open lattices and their structural behaviour investigated."

"Particular attention is paid to evaluation and analysis of Shukhov's tower calculations and the assumptions made for the structural model. His historical calculations are compared to the results of modern calculations."

"Shukhov's design process is reconstructed and the development of the water towers... illustrated."

"Until now, the form and geometry of the hyperbolic lattice structures have only been investigated to a limited extent."

"A paper by Peter de Vries discussed the stiffness of simple hyperbolic lattice structures and highlighted a single connection between geometry and structural behaviour. The focus... is... on a simple form of hyperbolic lattice structure which always has the intermediate rings positioned at intersection points of the lattice members."

"[T]he form and structure of the Sukhov-built towers were developed not on geometrical or constructional criteria alone, their designs specifically took into account considerations."

"The chapter "Geometry and form of hyperbolic lattice structures"... deals with the form and geometry... A precise description of the mathematical principles of a one-sheeted hyperboloid precedes an explanation of the parametrisation..."

"[T]he chapter "Structural analysis and calculation methods"... considers the principle means of transfer of vertical and horizontal loads and describes the interactions between geometry and structural behaviour. Then... an explanation of the theoretical principles of determining a lattice tower's ultimate load capacity."

"The chapter "Design and analysis of Sukhov's towers"... is devoted to consideration and analysis of Sukhov's structural calculations... Sukhov's design process is reconstructed based on... calculations of five different water towers. From... tables stored in the Moscow city archives, a summary... is produced to chart the development of the towers over more than three decades..."

"An analysis of the design and construction of the NiGRES tower on the Oka... The initial ensemble of four electricity transmission masts represents the consummation of Shukhov's tower construction method. Only one... remains... today."

"The final chapter "Towers in comparison"... contains an extensive table and drawings of 18 towers."

"It is hoped that the examination of Sukhov's form of construction made public in this book will give an impetus to new applications in architecture."

"[A] new reconfigurable doubly-curved structure has been developed for a canopy roof."

"[A] series of kinetic structures which are capable of geometric transformations have been developed. ...[T]he most impressive ones are deployable bar structures with [a] single degree-of-freedom ...These structures ...may become stable and carry loads ...Therefore ...may offer viable solutions for architectural applications, especially for temporary buildings, emergency shelters, exhibition halls, outdoor recreation facilities or sporting fields ...[M]ost of them are composed of scissor like elements (SLEs) ...which is a complex structural system ...[P]resent solutions are insufficient to constitute real form flexibility, because they are limited to... forms such as singly-curved vaults and doubly-curved synclastic s."

"Due to... complexity... doubly-curved anticlastic surfaces such as hyperboloid and hyperbolic paraboloid (HP) have been rarely used for deployable structures. In fact, anticlastic structures can be easily constructed using simple straight bars rather than SLEs since their geometric forms can be generated by s..."

"[A]nticlastic structures are capable of resisting... various design loads through their curvatures and twists. Thus, their structural efficiency is more than ...others. ...[W]e have decided to use HP ...as a [deployable] canopy roof structure."

"In 1829... Nikolai Ivanovich Lobachevsky published a disproof of Euclid's fifth or using the case of a doubly curved surface, thereby establishing non-Euclidean geometry."

"According to Elizabeth C. English, there was a direct connection between the mathematical discoveries of Lobachevsky and the structural explorations of"

"The "idea of the " and the first... diagrid structure have been credited to... Shukhov. The design evolved as an efficient and easily constructed tower for carrying a large gravity load... a water tower. The "Shukhov Tower"... 1896, relies on the use of a diagonal lattice of steel angles, constrained laterally... by steel rings. ...The tower is hollow, requiring little resistance to wind loads ..."

"Shukhov is credited with the construction of some 200 towers using this method ..."

"Although the slender steel sections, when formed into the hyperbolic paraboloid shape, did undergo some bending, a diagrid shape emerges, using a combination of straight segments that are joined at their nodal points of intersection."

"The Shukhov towers tended to use much longer steel sections and overlap them at their crosspoints, rather than using the crosspoints as "nodes" in the fashion of later or spaceframe structures."

"[T]he diagrid form could support both the gravity loads and the lateral loads without requiring additional means. In comparison, the new skyscraper types that were under development at this time used a steel frame to support the gravity loads... while the central core provided the stiffness required to resist wind loads. Where additional resistance was required, it was usually the core that carried the bracing."

"The School of Engineering and Construction which came into being in Russia after the reforms of the 1860s, and in connection with large-scale railway construction towards the end of the nineteenth century, soon acquired a worldwide reputation. It produced distinguished theorists and practitioners who included Belelyubsky, Loleit, Proskuryakov, Shukhov and Yasinsky. The engineering work incorporated in the most diverse kinds of buildings in Russia during the last quarter-century before the Revolution show that this country not only kept pace with the more developed parts of Europe and the USA, but outstripped them in certain fields, in terms of engineering design, as well as the use of modern construction techniques and new materials. Thus Shukhov produced many original designs unparalleled in work done abroad. At the Nizhny-Novgorod Exhibition in 1896... several original designs by Shukhov appeared, the most important of which were latticed: suspended latticed roofs for exhibition halls with a circular, elliptical and rectangular ground plan, latticed roof vaults and hyperbolic latticed towers. This category of structure also included the dual curvature roof designed by Shukhov in 1897-98 to cover the workshop at the Vykhsusnk factory."

"Forms of spanning which have come into use in recent years were foreshadowed in various forms of latticed structures designed by Shukhov before the end of the last century—guyed structures, the spanning of dual curves by structures of standardized rods, the provision of curved 'hyperbolic' profiles by means of a straight component, using straight rods in Shukhov's case."

"Russian engineers made many new and stimulating contributions to the design and construction of multiple-span lattice metal bridges, a great number of which were needed in railway work because of the multitude of large rivers in Russia. Ferro-concrete was first used in buildings there at the beginning of the twentieth century. Russian engineers... made their own contribution to the development of structural techniques in this area."

"The creative principles of innovative trends such as Rationalism and Constructivism were well understood by engineers and constructors bent on applying the latest technological achievements. Great engineers such as Shukhov, [Artur] Loleit and [Hermann] Krasin, were happy to work with innovative architects. They jointly explored new ways of developing architecture, and engineers became active members of Asnova and Osna. ...In the twenties... Soviet architecture set tasks for the building industry which prompted the employment of new materials and structural elements, and raised building standards. Engineering technology in the building industry achieved great successes during this period, such as the metal structures by Shukhov and Krasin, Loleit's work in the field of ferro-concrete, the elaboration of modern timber work by Karlson and the production of new hyperbolic paraboloid roofing by Markarova. The very latest structures and building materials, as well as modern production methods, were applied in the construction of engineering and industrial buildings such as Shukhov's radio tower in Moscow in 1922 and Krasin's viaduct at the Shatura power station in 1925."

"[H]yperbolic s are associated with nuclear and thermal power plants... they are also used... in some large chemical and other industrial plants. [T]hey are high rise structures in the form of doubly curved thin walled shells of complex geometry..."

"The in-plane membrane actions primarily resist the applied forces and plays the secondary role in these special structures."

"The first hyperboloid shaped cooling tower was introduced by the Dutch engineers and Gerard Kuypers and built in 1918 near having 35 meter height."

"The hyperbolic geometry has advantage of a negative which makes it superior in stability against external pressures..."

"The widened bottom of the tower accommodates large installation of fill to facilitate the evaporative cooling of the thin film of circulated water. Narrowing effect of the tower accelerates the of evaporation and diverging top promotes turbulent mixing which increases the contact between hot inside air and cooler outside air."

"The... structure is made of high-strength [cement,] Reinforced... Concrete... in the form of hyperbolic thin shell standing on diagonal, meridional, or vertical supporting columns and radial supports. The shell is sufficiently stiffened by upper and lower edge members."

"[T]o achieve sufficient resistance against instability, large cooling tower shells may be stiffened by additional internal or external rings which may also be used as repair or rehabilitation..."

"The hyperbolic form of thin-walled towers provides optimum conditions for good aerodynamics, strength, and stability."

"[T]he first cooling tower shell [to be] analyzed by means of a shell bending theory [was in 1967]."

"[T]he most preferred method of the modeling and analysis of NDCT [natural draft cooling towers] is [the] (FEM)."

"Determination [utilizing nonlinear static analysis] of the ultimate strength of the cooling towers... subjected to the severe quasistatic wind loads is one of the [research] objectives... for... structural engineers. Various nonlinear factors, such as the material nonlinearities in the concrete and reinforcing steel, tensile cracking, the bond effects between concrete and steel in the cracked concrete which is known as the tension stiffening, the large displacement effects, and so on; need to be taken into account..."

"Mahmoud and Gupta... concluded that the failure of the Port Gibson Tower [in] Mississippi was caused by the circumferential in the vicinity of the throat rather than the yielding of the reinforcement, which contradicts... previous researchers."

"Deformation response and ultimate strength of RC shell structures are governed predominantly by material response of concrete and reinforcing steel, tensile cracking of concrete, [and] bond between concrete and steel.... Softening response of concrete due to quasi-brittle cracking in tension also... influences the nonlinear response by inducing loss of strength and stiffness... Due to all [of] these, analysis requires attention for realistic modeling of the layer of shell concrete confined between the reinforcement layers. ...[O]ne of the most challenging areas... is the modeling techniques using the layered elements."

"The NDCT [natural draft cooling tower] shell structures are submitted to environmental loads such as wind, earthquake and thermal gradients that are in nature. The dead loads, settlement, and construction load are... common... and various accidental loads, e.g., explosion [are]... experience[d]... in their lifetime."

"[I]n 1967, closed-form expressions [were] derived by Gould and Lee... for determining... stresses in the shell and corresponding deformations under static seismic design load."

"Abu-Sitta and Davenport... investigated the effects of dynamic earthquake loading. ...[I]nduced dynamic stresses were related to equivalent membrane stresses from static loads, resulting in... a simplified earthquake analysis procedure."

"Asadzadeh et al... studied the structural response... under static wind and pseudo static seismic forces. ...[T]wo types of... column supports at the base of the towers had been considered... The structural response... under wind and earthquake was... completely different for the towers supported on different columns."

"Asadzadeh et al... studied the effects of the inclination angle of the supporting columns on the dynamic response of the cooling towers. ...[S]tiffness of the structure increases with increase in inclination angle of the supporting columns resulting in decrease of the period therefore altering the resistance... against the earthquake loading. ...[T]he hyperbolic structure... can be optimized by finding the optimum inclination angle of the supporting columns."

"Wind is the prime lateral load and its combination with self weight of the tower shell can cause the instability leading to catastrophic failure."

"After the sudden collapse of three immense cooling towers at Ferry-Bridge Power Station in England in 1965, experimental and theoretical investigations had been done in... the stability of hyperbolic shells to study the parameters increasing the wind resistance and buckling safety..."

"The wind-induced response... is the key factor to improve safety and to reduce tower crack[ing]..."

"Form... found that the construction of the stiffening rings significantly influenced the safety factor (BSF) and structural buckling stability... He showed that adding 2, 3, or 4 stiffening rings to the cooling tower increase the BSF of the R.C. shell by a factor of 1.65, 2.32, and 2.80, respectively."

"Sabouri-Ghomi et al... investigated... buckling stability of R.C. cooling towers supported on X-shaped columns by considering... parameters such as the number, dimension, and location of stiffening rings... The stiffening rings behaved flexibly or rigidly, depending on their dimensions. The number of flexible stiffening rings required to maximize the buckling safety factor was found to be higher than the number of rigid stiffening rings..."

"Ref: S. Sabouri-Ghomi, M.H.K. Kharrazi, and P. Javidan, "Effect of stiffening rings on buckling stability of R.C. hyperbolic cooling towers," Thin Walled Structures, vol. 44, no. 2, pp. 152-158, 2006."

"Zhang et al... studied the effect of the stiffening ring... to improve the dynamic properties and the wind resistance... They... concluded that for the latitude and meridian directions, the stiffness in the latitude direction contributes more... and... the location where the maximum modal displacement of the unstiffened HCT appears will not always be the most effective place for an additional stiffening ring unless the mode shapes of the unstiffened and stiffened HCTs are similar."

"Consideration of the soil–structure interaction... is extremely important when the soil or the foundation medium is not very firm. ...[U]nder ...dynamic loadings, the structure interacts with the surrounding soil imposing soil deformations. These... change the response of the structure."

"Noorzaei et al... analyzed the cooling tower–foundation–soil system under vertical and lateral load generated due to self-weight and wind loads. In this study, the unsymmetrical wind pressure distribution in terms of [were] given..."

"The collapse of three natural draft cooling towers at the Ferry bridge power station in 1965... [was] due to the inadequate design for the wind forces..."

"In recent years... numerical simulation... has been applied to describe the collapse of structures, e.g., the collapse of cooling towers under blasting demolition... and the collapse of the World Trade Center..."

"Due to the complexity of the building procedure, uncertainties in the material properties as well as differences between the theoretical and the real geometry... reliability analysis... seems... indispensible..."

"This review is a complete collection of the studies done for cooling towers and... [gives] updated and sufficient materials for the researches in this field."

"We present a new mechanical model of interatomic bonds, which can be used to describe the elastic properties of the carbon allotropes, such as , diamond, , and s. The interatomic bond is modeled by a hyperboloid–shape structure."

"[T]here are... approaches that are closer to the field of the classical mechanics... so–called structural or discrete-continuous methods... The most straightforward example... is a modeled by the solid deformable rod... [T]he interatomic bonds are modeled as a deformable body or a construction. ...[T]hese approaches... can be implemented in standard computing packages based on the finite–element, boundary–element, or s. These methods can be considered as the bridges between the s of atomistic and continual models of the material."

"In this paper, the carbon bond model is built on the symmetry properties of the hyperboloid. These properties allow it to achieve a high ratio of the lateral and longitudinal , therefore the hyperboloid shapes are widely used in the engineering to create lightweight constructions consisting of straight beams that are known for being able to carry a large load while achieving a low use of raw materials."

"[T]he first hyperboloid tower was built by Russian engineer V.G. Shukhov in (1896)... Being widely demanded in architecture and engineering, such models still haven’t found a wide use in micro- and . It appears that the analogy drawn from the macro level will allow to describe correctly the properties of carbon materials at the micro level."

"Alongside Shukhov’s drawings and sketchpads... a typescript produced by Shukhov’s former employee Grigory Kovelman... put together an extensive overview of Shukhov’s inventions and projects, both as a biographer and as a specialist who had worked with Shukhov.... Elena Shukhova... grand-daughter... presents extensive biographical details in Vladimir Grigorevich Shukhov. The First Engineer in Russia... Art of Construction... is a valuable collection of articles about Shukhov and his various inventions, written by... specialists. It includes... examples of his calculations. Shukhov’s own book Rafters... discusses the mathematical investigations which led him to conceptualise the spatial lattice structure, describing it as 'an optimisation process'."

"In 2010, the journal Detail published an analysis of Shukhov’s constructions, calling his approach to design 'an early example of ’..."

"Vaulted gridshell constructions... were formed with thin metal arches turned away from the frontal position at a particular angle. They thus worked as one continuous resilient truss. ...Each arch was made with rigid metal strips of equal length... during the assembling process, each piece was bent equally. ...It was the first time in the world’s building practice that double-curved spatial vaults were created with single type rod elements ..."

"Shukhov’s lattice-suspended and vaulted structures represented a carrying surface, which could be shaped in any form. ...The density of the grid made it possible to attach it to the shell without additional structures. ...[T]he grids were two to three times lighter than roofs with conventional frames..."

"The final and most unusual of the gridshell structures presented at the Exhibition was the 32-metre-tall lattice hyperboloid water tower. Everything was amazing in that first Shukhov tower—everything in it was some structural and geometric puzzle: straight rods and the external silhouette double curvature, the openwork lightness below and the solid heaviness above."

"The water tower was a unique structure of its time... According to Cooper, the idea... came directly from an imaginary hyperboloid geometry, invented by... Lobachevski in 1829..."

"Grigory Kovelman writes that Shukhov told him he had been thinking about the properties of hyperboloid structures for a long time, that he had studied hyperboloid forms at the Technical School, and that apparently the moment of enlightenment came about when he saw an up-ended wicker wastepaper basket with a focus on top of his desk. According to Shukhov, this was when he understood clearly how a hyperboloid structure with its curved surface [was] generated by straight rods..."

"[T]he structure of the lattice tower was a spatial system, where the load was equally spread along the surface. ...Aiming to optimise the design process, soon after building the tower Shukhov presented the standardised elements of the tower structure in a table format... with the aid of which it became possible to design a new water tower according to a client’s requirements in twenty-five minutes..."

"The Radio Tower in Moscow is a gridshell which aims for structural efficiency. Its minimal surface and open lattice structure help in reducing the wind load, one of the main challenges in high-rise building design. ...Shukhov's design logic focuses on structural . The rings between the different segments offer additional reinforcement to create an equilibrium between minimal material consumption, structural efficiency and geometry."

"As hyperboloid structures are double curved, that is simultaneously curved in opposite directions, they are very resistant to . This means that you can get away with far less material than you would otherwise need..."

"Single curved surfaces, for example cylinders, have strengths but also weaknesses. Double curved surfaces... are curved in two directions and thus avoid... weak directions."

"[T]his is the magical part... despite the surface being curved in two directions, it is made entirely of straight lines. Apart from the cost savings of avoiding curved beams or shuttering, they are far more resistant to buckling because the individual elements are straight..."

"This is an interesting paradox: you get the best local buckling resistance because the beams are straight and the best overall buckling resistance because the surface is double curved."

"The hyperboloid is the design standard for all nuclear cooling towers and some coal-fired power plants."

"When designing... cooling towers, engineers are faced with two problems: I. The structure must be able to withstand high winds and II. They should be built with as little material as possible... The hyperbolic form solves both..."

"For a given diameter and height of a tower and a given strength, this shape requires less material than any other form. ...Hyperboloidal towers can be built from or as a steel lattice, and is the most economical such structure for a given diameter and height."

"The presented orthogonal fitting algorithm can be applied easily for ellipsoid, and sphere also other surface[s] such as paraboloid."

"In 1899... V. Shukhov... patented the principle of constructing hyperboloid gridshell structures based on a hyperboloid of revolution. ...A one-sheet hyperboloid is a connected surface having negative at each point. Through any point of this surface, two intersecting [straight] lines can be drawn, completely belonging to it. Thus the... surface can be formed by the set of straight lines. It the steel beams would be placed along these lines the shape... could be retained under... external loading... [I]n Shukhov's towers horizontal rims [rings] were used... located at different levels... The stability... was ensured by numerous riveted connections... During the installation... the straight angles of the metal profile was somewhat deformed... [at] the... intersecting elements in order to ensure maximum contact... by rivets."

"The main hazard for high-rise structures is the loads caused by wind gusts. The grid shell design... minimize[d] their influence. Open-work design... ensured... sufficient strength, high stability and low metal consumption. ...[C]onsumption of metal per unit height... was three times less than... the ..."

"... Ještěd in Czechia, Guangzhou in China... and Khan Shatir Shopping-Entertaining Center in Kazakhstan, Aspire Tower in Qatar... are vivid examples of using... the hyperboloid principle... [in] modern buildings."

"191 of the Shukhov's Towers (from known near 200...) have been irretrievably lost during... the 20th century... [Some] towers were destroyed because their continued use for water supply has become impractical. To use them for another purpose... large investments were necessary."

"I could have restricted myself in this book to only the most sober physical calculations. But in order to create the necessary respect for my idea (otherwise a realization of this idea is unthinkable), I felt impelled to draw a few pictures of the future... and I have set up some fantastic claims. Naturally, here also, I have said nothing that might not be possible by present scientific standards, and I will now show that I am also on completely scientific ground with this idea of a reflector."

"A rocket with the necessary equipment is sent aloft and there given a lateral propulsion which puts it into an elliptical orbit around the earth. I will call this rotation about the earth "revolution". Major axis perpendicular to the ecliptic, perigee in the south 1,000 km above the earth's surface, apogee in the north 5,000 km above the earth's surface."

"The miniature facets are adjusted by hand... It is sufficient to simply let the sun shine on the miniature reflector and then turn the facets so that the reflected light strikes those parts of the globe corresponding to the region to be irradiated."

"Whether we must seek to constantly reflect the light on the earth vertically or are, in fact, able to is another question. I will assume that we can in order to study the single elements which determine the path of the reflector. (s are also used in calculations, although it is known that they do not exist.)"

"In the south... the main task of large reflectors... of making polar regions arable, is not feasible. If the glaciers of Antarctica were melted, the level of the ocean would rise uncomfortably (6-8 m). Hopefully, by then man will be sensible enough at least to leave a cold zone for the protection of nature."

"So for the southern hemisphere and the tropics there would only remain the illumination of large cities at night and perhaps supplying solar plants with more light as well as the influencing of the weather."

"In the north, on the other hand, outside of , there are no such masses of land-ice (however much ice there may be, no danger arises from melting ice that floats in the water), and the glaciers of Greenland will remain because if their high location and because there will be more snowfall on Greenland if the polar sea melts."

"The cultural tasks are... possible to fulfill. For example, if a sea route to the ports of Siberia is to be kept ice-free, a route must only be chosen that runs approximately in the direction of the winter wind from the Gulf Stream... light is thrown on a relatively narrow and short strip running from east to west... to the extent that the sky clouds over at this place. ...[T]he direction of the wind and ...the earth's rotation coincide. Hereby the earth always rotates as we need it ...By the time the light patch has passed along the whole stretch, the fog at the beginning will either have settled or been blown away... Then one can begin at the beginning again, Since the clouds hold the heat above the shipping lane... a reflector 100 km in diameter is... sufficient."

"Enough of this. They are only dreams of the future. Bold ones? Perhaps, but we have already experienced... bolder ideas. Who would have believed in 1894 that, a few years later, one would see through a person by means of Roentgen rays? PHILANDER's statement (Medical Fairy Tales), "Man will be made transparent like a jelly-fish", was bolder than this dream of the future; that required finding something completely new, while here we are dealing with laws of nature already known.—Accomplishing these things will certainly require the conversion of enormous energies. But were not hundred times greater sums of money expended during the World War? In one year, the nations of Europe spend more on smoking and drinking than the whole sodium reflector would cost. War and narcotics are quite unnecessary things, yet more money is spent on them than on something useful. Should not mankind, in an exceptional case, also save something for constructive work?"

"Ref: Philander, Medizinische Märchen"

"shields for planets such as Venus or Mars would... be large, complex structures requiring vast amounts of lunar or asteroidal material... and long-range transportation... One... stepping stone to understanding and mastering the technologies and processes... would be the construction of a shield to offset the greenhouse effect on... Earth. Such... would not require interplanetary capabilities."

"The time required for the removal of... [[w:Greenhouse gases|[greenhouse] gases]] from the atmosphere by natural processes is... uncertain: current estimates are several centuries. The uncertainties... [have] led to calls for... restrictions on the generation of greenhouse gases. ...The existence of a possible technical solution could... have a major short-term impact in influencing short term consumption restrictions, even if the solution could not be implemented until the next century."

"A conceptually simple method for offsetting the greenhouse radiation trapping effects would be to decrease the solar heating by the use of a space-based solar shield."

"Approximately 2% of the solar radiation reaching Earth must be blocked to offset the predicted greenhouse trapping in the next century."

"An ideal opaque shield would scatter the Earth bound solar energy into diffuse infrared energy."

"The shield may also be transparent and simply scatter the visible photons away from the Earth. ...A glass shield may act as a prism to deflect the sunlight away from the planet in accordance with ."

"can be formed into glass for either a transparent or opaque shield."

"The glass may be launched to the shield location by a . A number of studies have indicated that mass drivers are feasible and economical for launching unmanned payloads from the lunar surface. If the glass sheet is sufficiently flexible it may be formed into sheet on the lunar surface and launched in rolls."

"Oberth... began the book Men in Outer Space: New Projects for Rockets and Space Travel... written in the style accessible to the general reader. ...Published in 1955 in German, it was translated into English, French, Italian, Dutch, and even in Croatian! ...Oberth's new book was indeed "cosmic," and this gave it a cardinal distinction from his classic book of the 1920s. ...A supplemental chapter ...is devoted to "s," a theme which occupied Oberth all his life. A short description ...is already present in the 1923 book. In 1929, when he published his fundamental work, Ways to Space Travel, he included a much more comprehensive description... in the chapter... "Space Stations." ...[A]lmost the entire chapter is devoted to space mirrors. In the 1954 book... a new varient... is presented. Eventually in Bucharest in 1978, an entire book (in German) was devoted to this theme. ...[T]he primary purpose for the space mirror would today be called an ecological one ...At the time ...there was ...no robotics technology, and he assumed all the work after ...erection ...would ...be carried out manually by astronauts."

"[A] giant net (similar to a trawl) would be erected in outer space, constructed in a hexagonal mesh pattern. This net would be stretched out and a tension sufficient to rotate the entire net would be maintained by . The rotation would be begun by special rockets and... continue because it was in a vacuum. The diameter of each hexagon would be about 10 kilometers, and the entire mirror would have a circular disk shape with a diameter of about 100 to 200 kilometers. Within each hexagon, a round mirror approximately 10 kilometers in diameter, would be installed. ...[Each] single mirror would be capable of being [independently] tilted... initiated by... electric s."

"Such a mirror, he asserted, could not only light up the cities at night... but could also have a decisive influence on weather and climate."

"[T]he ice in the usable areas of the north polar seas could be melted... to navigate the northern coasts of Europe and Siberia year round. The warming of the Caspian Sea could... produce rain in arid regions of Central Asia. Directing... rays... where spring and autumn frosts are expected would allow... increase[d] fertility... Oberth claimed... it would open up... predicting the weather, but also... determining the weather."

"Oberth proposed to shade planets located close to the sun... with gigantic cosmic shields... Vice versa, the planets... further from the sun... would be warmed... with... gigantic cosmic mirrors."

"[H]is belief... a reduction in the cost of building large structures in outer space could be achieved by delivering the necessary materials from the moon... [H]e presupposed the existence of the necessary industrial plants on the moon, but the end result would be a thousand-fold reduction in the cost of building large structures in space."

"[T]he problem of possible changes in climate may be better solved by cooperative application of modern technologies rather than by international measures focused on prohibitions."

"Greenhouse warming of the Earth due to human activities is a possibility, moreover one for which mitigative/remedial actions of the types proposed here can be at once deliberate and effective. In contrast, Ice Age-severity cooling... that have occurred quasi-periodically many times during the last 1.2 million years, is a practical certainty. Moreover, a several-decade duration cold snap of Ice Age Maximum temperature-drop is known to have occurred in the Northern Hemisphere with essentially no warning during the last interglacial period, under precursor climatic conditions only slightly warmer than the present-day one."

"A wide range of techniques has been proposed for increasing the planetary , ranging from painting surfaces white to placing mirrors in orbit between the Earth and the sun."

"This sense of taboo was based on a range of arguments against research on albedo modification that have been raised by the broader scientific community, including: 1. the so-called moral hazard issue, that is, the possibility that research on climate engineering could be perceived as an implicit legitimization, and thus reduce the motivation for mitigating anthropogenic emissions; 2. the concern that reducing temperatures by albedo modification could distract from other impacts of a fossil-fuel-based economy and the resulting CO2 emissions, such as ocean acidification; 3. the “slippery slope” concern that research into understanding the potential effectiveness could cascade toward the development and deployment of the techniques under investigation; and 4. contention about the perceived “techno-fix” approach to address environmental challenges, that is, the notion that technology-caused problems can simply be fixed with more and better technology."

"[G]iven the balance of results of model studies over the last decade... and the challenging directions that this implies both for future research and also for sociopolitical aspects, especially public perception and the development of good governance principles, we have to conclude that the overall verdict is still out. The responsibility still resides with the scientific community to conduct research and engage in the broader dialogue in a responsible way, so that whatever the outcome, historians will hopefully look back and conclude that it was indeed of value—and in that sense a moral imperative—to begin carefully investigating this topic... Perhaps this will already be clear by the time of the next special section like this one, which, following those in 1996 and 2006, should be due in 2026."

"Mercury doesn't contribute its valence electrons readily to the [electron] soup. The thinner soup can't bind the mercury atoms together very strongly. Mercury atoms easily slip past and away from each other. Heat easily overcomes the weak binding between mercury atoms, and mercury boils and melts at lower temperatures than any other metal. Because the valence electron soup is thinner for mercury, its electrical and thermal conductivity are poor."

"While Paracelsus was pressing his doctrines on all sides, and endeavouring to lead chemistry into a new channel, another, Agricola, was quietly at work among the mines of Saxony, utterly indifferent to all but the advance of his science. It is to Agricola's systematic observations that we trace the beginnings of the science of mineralogy. In metallurgy, also, he was a pioneer, the first to give a clear and succinct account of the preparation of many metals. He taught the condensation and purification of sulphur given off during the roasting of many s, the separation of silver from gold by means of nitric and sulphuric acid, the preparation of such bodies as salt, , and saltpetre on a large scale. The apparatus described by Agricola and employed by him for the and testing of ores were still in use at the end of the eighteenth century. Agricola stands out solitary among the men of his time as one pursuing chemistry from pure love of the science; his work had no other aim than the increase of knowledge."

"Iron yields to certain degrees of beatings or repeated pressure; its impenetrable molecules, purified by man and made homogeneous, disintegrate; and, without being in fusion, the metal no longer has the same virtue of resistance. Marshals, locksmiths, tool makers, all the workers who constantly work this metal then express the state of it by a word of their technology: "The iron is retty!" they say, appropriating this expression exclusively devoted to hemp, the disorganization of which is obtained by retting. Well, the human soul, or if you will the threefold energy of body, heart, and spirit, is in an iron-like situation, as a result of certain repeated shocks. It is thus with men like hemp and iron — they are retty."

"A neutral salt, which is composed of an acid and alkali, does not possess the acrimony of either of its constituent parts. It can easily be separated from water, has little or no effect upon metals, is incapable of being joined to inflammable bodies, and of corroding and dissolving animals and vegetables; so that the attraction both of the acid and alkali for these several substances, seems to be suspended till they are again separated from one another."

"One worker on one of the supports... either manually or with a trowel distributes the mortar over the chicken wire... Simultaneously, another worker from within the room... holds the mortar which is applied from the outside with a metal float or trowel in order that the mortar does not fall. Once this operation is completed, the required finish is applied both from the outside and the inside."

"The export of into Italy was strictly forbidden; but aluminium was almost the only metal that Italy produced in quantities beyond her own needs. The importation of scrap iron and into Italy was sternly vetoed in the name of public justice. But as the Italian metallurgical industry made but little use of them, and as steel billets and were not interfered with, Italy suffered no hindrance. Thus, the measures pressed with so great a parade were not real sanctions to paralyse the aggressor, but merely such half-hearted sanctions as the aggressor would tolerate, because in fact, though onerous, they stimulated Italian war spirit. The League of Nations, therefore, proceeded to the rescue of Abyssinia on the basis that nothing must be done to hamper the invading Italian armies. These facts were not known to the British public at the time of the election. They earnestly supported the policy of the sanctions, and believed that this was a sure way of bringing the Italian assault upon Abyssinia to an end."

"The Franklin sold at £4. 6s, each at the furnace, and at Philadelphia £18 per ton, the price varying with the metal."

"The art of tempering and iron developed in India long before its known appearance in Europe; , for example, erected at Delhi (ca. 380 A.D.) an iron pillar that stands untarnished today after fifteen centuries; and the quality of metal, or manner of treatment, which has preserved it from rust or decay is still a mystery to modern metallurgical science. Before the European invasion the smelting of iron in small charcoal furnaces was one of the major industries of India. The Industrial Revolution taught Europe how to carry out these processes more cheaply on a larger scale, and the Indian industry died under the competition. Only in our own time are the rich mineral resources of India being again exploited and explored."

"[T]here are not really 2-dimensional metals because conventional metals, for physics reasons... don't really like to be in the 2-D state, and most of them immediately oxidize anyway... So by discovering ... we created materials which are 2-dimensional metals. So we... closed the gap in existing the series of materials."

"Tradition has it that not only concerned himself with the unification of Egypt but also with the control of the river: to him is attributed the first damming of the Nile, the digging of dikes for agricultural purposes and indeed the first attempt to control and apportion the waters of the river. The wealth of Egypt was thus, with , based upon its agricultural output. However, unlike Mesopotamia, the Egyptians had on their doorstep a number of mineral resources that they were able to exploit with little effort, including copper ores, gold and a wide range of rocks suitable for building and the making of a wide variety of ornaments. [S]hortly before the year 3000 metallurgists made a discovery that was to transform the entire "industry." ...by mixing a small quantity of tin ore with the copper ores when... smelted... they discovered the alloy . The occurrence of tinstone... does not occur in the same type of deposit as do the ores of copper, but rather, [near] veins of gold. ...Thus tinstone ...may well have been noticed during washing for gold... finding that the little black lumps of ore were relatively heavy, presumably made various attempts at smelting them until they arrived empirically at a suitable alloy... [T]he effect is to reduce the melting point... they had a far more fluid metal that was much easier to cast. ...the quality of casting improved dramatically."

"Aristotle had considered metals to be formed by the combination of moist and dry exhalations, and in the Jabirian works these... are... vapours of mercury and sulphur. The cause of the different metals was the... quality of the sulphur... The term sulphur ...as a component of metals probably referred to a volatile combustible material to which no... substance corresponded exactly. Likewise mercury... may... have been... an approximation to the other volatile liquid component of metals. ...The notion that metals contained a combustible principle persisted, and... provided the inspiration for the phlogiston theory."

"The Jabirian alchemists... believed that metals were ultimately composed of the four Aristotelian elements earth, water, air and fire... A base metal had to be treated with a medicine or elixir to adjust... qualities... with the proportions of gold. ...[Q]ualities of heat, cold, moisture and dryness could each be separated in pure form. ...First they subjected various organic materials to ... which often resulted in... a volatile combustible... (air), a liquid (water), a combustible tarry material (fire) and a dry residue (ash). [Each of] [t]hese elements were supposed... composed of two qualities, and... could be isolated by... purification. Thus water... could be converted into pure cold by repeated distillation... and further [distillations] in the presence of a drying agent. The resulting pure cold... a brilliant white solid."

"My invention shows a new product which helps to replace timber where it is endangered by wetness, as in wood flooring, water containers, plant pots, etc. The new substance consists of a metal net of wire or sticks which are connected or formed like a flexible woven mat. I give this net a form which looks in the best possible way, similar to the articles I want to create. Then I put in hydraulic cement or similar bitumen tar or mix, to fill up the joints."

"Nothing can vex the Devil more Than the name of him whom we adore. Therefore doth it delight me best To stand in the choir among the rest, With the great organ trumpeting Through its metallic tubes, and sing: Et verbum caro factum est! [And the Word was made flesh!] These words the devil cannot endure, For he knoweth their meaning well! Him they trouble and repel, Us they comfort and allure, And happy it were, if our delight Were as great as his affright!"

"In the history of war and society we single out three main innovations to describe significant changes before 1800: the introduction of metal, when humans abandoned stone weapons for ones made from and iron; the domestication of the horse, which gave warriors greater mobility and speed; and the introduction of , which transformed war on land and at sea. (Since other parts of the world, such as the Americas, did not have horses until the Europeans brought them in the sixteenth century and some parts of the world, such as Australia, never developed metal weapons, not all human societies have experienced change at the same time.) In each case, of course, many other things were happening both to technology and to society. Metal weapons were only a part of the story: societies had to develop the soldiers and the infrastructures to make use of them. Horses were more formidable when the enabled them to pull s or later on when they could carry armed warriors. The introduction of gunpowder too was accompanied by other important developments: in metallurgy, for example, so that guns did not explode when they were fired, or in the design and navigation of ships, so that they could make use of the new cannon."

"The metals are all essentially identical; they differ only in form. Now, the form brings out accidental causes, which the experimenter must try to discover and remove, as far as possible. Accidental causes impede the regular union of sulphur and mercury; for every metal is a combination of sulphur and mercury. A diseased womb may give birth to a weakly, leprous child, although the seed was good; the same is true of the metals which are generated in the bowels of the earth, which is a womb for them; any cause whatever, or local trouble, may produce an imperfect metal. When pure sulphur comes in contact with pure mercury, after more or less time, and by the permanent action of nature, gold is produced."

"Mercury as a liquid metal is capable of dissolving other metals and forming metallic solutions. These are generally called 'amalgams.' The formation of these solutions is often accompanied by the development of a large amount of heat—for instance when and sodium are dissolved... but sometimes heat is absorbed, as... when is dissolved. ...[T]he solution of metals in mercury is accompanied by the formation of definite chemical compounds of the mercury with the metals dissolved. ...[I]n many cases such compounds have undoubtedly been obtained, and their existence is clearly shown by the evident crystalline structure and characteristic appearance of many amalgams."

"Sonorous metal blowing martial sounds, At which the universal host up sent A shout that tore hell's concave, and beyond Frighted the reign of Chaos and old Night."

"Few would defend a small view of Alchemy as "Mother of Chemistry", and confuse its true goal with those external metal arts. Alchemy is an erotic science, involved in buried aspects of reality, aimed at purifying and transforming all being and matter. Not to suggest that material operations are ever abandoned. The adept holds to both the mystical and physical work."

"The history of science may be described as the breaking down, and the crumbling away, of artificially constructed barriers. All the great men of science have been famous wall-breakers. ...It is worthy to remark that the central conception of the alchemists ...was the unity of natural phenomena. ...[T]heir arguments would be somewhat as follows—Plants grow from seeds ...animals become larger, stronger, and more complete ...the plant may well be called more perfect than the seed, and the full grown animal more perfect than the immature ...both plants and animals grow, come to their prime, and decay; and there are degrees of perfection in the animal and vegetable worlds. Now—we may suppose the argument of the alchemist... minerals and metals and all inanimate things should grow, and change, from less perfect to more perfect forms; as there are degrees of perfectness and dignity in among all living things, so... among all things; some metals disappear in acrid liquids, and... are... easily worn away, they are readily melted and burnt to ; but some other metals are not swallowed up by corrosive liquids, nor... worn away with ease, nor readily changed in fire; there are evidently noble and base metals, perfect and imperfect metals; and as the less perfect seed... produces the more perfect plant... rendered yet more perfect by cultivation, so the imperfect metals change slowly into... more perfect, and this... can be hastened by man's art and devices. ...[L]iving things are more perfect that inanimate things ...[M]uch more must changes from immature to mature forms be constantly proceeding from dead things like minerals and metals ...[I]t is probable that the plasticity of the minerals and metals will be greater ...hence ...it will be a comparatively easy thing to grow a noble metal like gold from ignoble metals like and copper, although it is impossible to change one kind of animal into another or one sort of plant into another ... A vague conception of the unity of nature... led to little accurate knowledge..; all that could be done was to perform a vast number of inaccurate and incomplete experiments, and to state the results in loose and slipshod language of the vague but sonorous hypothesis which prompted the experiments. And so although the hypothesis postulated the unity of nature there was no unity in the experimental results... collected to support the hypothesis. ...A man who sets out to discover what is must endeavour to put aside all his notions of what ought to be; it is only when he has gained a solid foundation of verified and accurate facts that he may venture to make a definite guess concerning the cause ...but unless he makes clearly stated guesses ...scientific hypotheses—he will remain a mere collector of half facts ..."

", The Story of the Chemical Elements (1897) pp. 16-19."

"RECOMMENDATION 6: Ferrocement in Disaster Relief. After fires, floods, droughts, and earthquakes... [t]ransportation is often disrupted... Supplies of bulky conventional building materials may be stranded outside the disaster area, whereas the basic ingredients of ferrocement may be available on the site or easily transported. The versatility of ferrocement also reduces logistical supply problems: wire mesh, cement, sand, and water can be substituted for the metal used for roofing, woods or plastic for shelters and clinics, asphalt for helipads, steel for bridges, and so on. Moreover, most ferrocement structures, though built for an emergency, will last long after the emergency is over. ...[F]errocement could be used at a disaster site for many purposes: Transport facilities, from simple boats to barges, docks, marinas, helipads, and simple floating bridges or short footbridges as well as road repairs. ...Food-storage facilities, quickly designed to local needs and quickly built, to preserve emergency food supplies. ...Emergency shelters such as, for example, the quonset type of roof, which is easy to erect and highly efficient. ..Public health facilities, such as latrines and clinics, built with ferrocement roofs and stucco-type walls of the same wire mesh and mortar. ...[C]adres of ferrocement workers could be trained in emergency applications and the supervision of local laborers at the disaster site."

"From this epocha the hypothesis of the tria prima seems wholly to have been abandoned: whilst a very different doctrine was proposed by Beccher in his Physica Subterranea [1669], and to which we are perhaps indebted for the present advanced state of chemical science; since he was the first to point out chemical analysis as the only true method of ascertaining the elements of bodies. According to his doctrine, all terrestrial bodies are composed of water, air, and three earths; viz. the fusible, the inflammable or sulphureous, and the mercurial. The three earths, combined in nearly equal proportions, compose the metals: when the proportion of mercurial earth is very small, they compose stones; when the fusible predominates, the resulting compounds are the precious stones; when the sulphureous predominates, and the fusible is deficient, the compounds are the calorific earths: fusible earth and water compose an universal acid, very much resembling sulphuric acid, from which all other acids derive their acidity; water, fusible earth, and mercurial earth, constitute common salt; sulphureous earth and the universal acid form sulphur. Such was the theory of Beccher, which was afterward considerably modified by Stahl."

"I've noticed that people who have never worked with steel have trouble seeing this... that the motorcycle is primarily a mental phenomenon. They associate metal with given shapes... pipes, rods, girders, tools, parts... all of them fixed and inviolable, and think of it as primarily physical. But a person who does machining or foundry work or forge work or welding sees "steel" as having no shape at all. Steel can be any shape you want if you are skilled enough, and any shape but the one you want if you are not."

"Alchemical theory was essentially static throughout the medieval period. ...Paracelsus was the herald of a new era, an era of . His contribution to alchemical theory lay in the addition to sulphur and mercury of a third principle, which he called '.' Materially this was recognised as the principle of uninflammability and fixidity. ...[T]he tria prima, or three 'hypostatical principles' could be interpreted in either a material or a spiritual sense. In the words of Paracelsus himself: 'Know, then, that all the seven metals are born from a threefold matter... Mercury is the spirit, Sulphur is the soul, and Salt is the body... the soul... unites those two contraries, the body and spirit, and changes them into essence.' ...similar to the material effect of the liquid menstruum, or Hermetic Stream, in uniting sophic sulphur and sophic mercury to produce the Philospher's Stone."

"It seemed probable that the large activity of some of these minerals, compared with and , was due to the presence of small quantities of some very active substance, which was different from the known bodies thorium and uranium. This supposition was completely verified by the work of M. and Mme Curie, who were able to separate from pitchblende by purely chemical methods two active bodies, one of which in the pure state is over a million times more active than the metal uranium. This important discovery was due entirely to the property of radio-activity possessed by the new bodies. The only guide in their separation was the activity of the products obtained. ...The activity of the specimens thus served as a basis of rough qualitative and quantitative analysis, analogous in some respects to the indication of the spectroscope."

"The magnetism as exhibited in iron is an isolated phenomenon in nature. What it is that makes this metal behave so radically different from all other materials in this respect has not yet been ascertained, though many theories have been suggested. As regards magnetism, the molecules of the various bodies behave like hollow beams partly filled with a heavy fluid and balanced in the middle in the manner of a see-saw. Evidently some disturbing influence exists in nature which causes each molecule, like such a beam, to tilt either one or the other way. If the molecules are tilted one way, the body is magnetic; if they are tilted the other way, the body is non-magnetic; but both positions are stable, as they would be in the case of the hollow beam, owing to the rush of the fluid to the lower end. Now, the wonderful thing is that the molecules of all known bodies went one way, while those of iron went the other way. This metal, it would seem, has an origin entirely different from that of the rest of the globe. It is highly improbable that we shall discover some other and cheaper material which will equal or surpass iron in magnetic qualities."

"[M]etals remained the alchemists' chief concern... they seemed in their own way alive, whereas the calces (s) from which they were manufactured crumbled to dust and looked like cinders. Theory at once suggested a natural analogy. The metal was formed from the calx by the incorporation of or spirit; and this theory of metal-formation long remained in favour, being revived around 1700 as the 'phlogiston' theory. The central problem about metals was to identify the volitile constituents which combined with the calces to form the finished metal. For a long time, the status of quicksilver was ambiguous... resembling much more the volatile reagents which corrode metallic surfaces: mercury, in fact, forms an amalgam with other metals, and is even capable of dissolving gold... So the Alchemy of Avicenna classed mercury as a 'spirit' rather than a 'body'..."

"Theophrastus, the successor of Aristotle, ...says, in the beginning of his book on fossils, 'stones are produced from earth, metals from water.' ...Theophrastus is perhaps the best observer among the ancients, whose works are in our possession, and [his] theories... cannot be considered as an unfavourable specimen of the theoretical physics of the age."

"[E]early chemical discoveries led to the pursuit of alchemy, the objects of which were to produce a substance capable of converting all other metals into gold: and an universal remedy calculated indefinitely to prolong the period of human life."

"The processes supposed to relate to the transmutation of metals, and the , were probably first made known to the Europeans during the time of the ..."

"Arnald of Villa Nova... was one of the earliest European inquirers who attended to chemical operations. ...[H]e firmly believed in the transmutation of metals; the same opinions are attributed to him and to Geber; and he seems to have followed the study with no other views than those of preparing medicines, and attempting the composition of the philosopher's stone."

"Beccher, ...after having studied with minute attention, the operations of , and the phænomena of the kingdom, formed the bold idea of explaining the whole system of the earth by the mutual agency and changes of a few elements. And by supposing the existence of a vitrifiable, a metallic, and an inflammable earth, he attempted to account for the various productions of rocks, crystalline bodies, and metallic veins, assuming a continued interchange of principles between the atmosphere, the ocean, and the solid surface of the globe, and considering the operations of nature as all capable of being imitated by art."

"had been used to tinge glass in in the sixteenth century; but the metal was unknown till the time of Brandt, and this celebrated Swedish chemist discovered it in 1733."

"The properties of , which was announced as a peculiar metal by Kaim in 1770, were minutely investigated by Scheele and Bergman a few years after."

"Scheele discovered in 1781; and soon after a metal was extracted from it by Messrs. Fausto & Juan José] D' Elhuyars."

"Platina had been brought into Europe and examined by Lewis in 1749 and in 1803, Descotils, Fourcroy, and Vauquelin announced a new metallic substance in it; but the complete investigation of the properties of this extraordinary body was reserved for Messrs. Tennant and Wollaston, who in 1803 and 1804 discovered in it no less than four new metallic substances, besides the body which exists in it in the largest proportion, namely, iridium, osmium, palladium, and rhodium."

"By researches, the commencement of which is owing to Messrs. Nicholson and Carlisle, in 1800, which were continued by Cruickshank, Henry, Wollaston, Children, Pepys, Pfaff, Desormes, Biot, Thenard, Hissinger, and Berzelius, it appeared that various compound bodies were capable of decomposition by electricity; and experiments, which it was my good fortune to institute, proved that several substances which had never been separated into any other forms of matter in the common processes of experiment, were susceptible of analysis by electrical powers; in consequence of these circumstances, the fixed es and several of the earths have been shewn to be metals combined with oxygene; various new agents have been furnished to chemistry, and many novel results obtained by their application, which at the same time that they have strengthened some of the doctrines of the school of Lavoisier, have overturned others, and have proved that the generalizations of the Antiphlogistic philosophers were far from having anticipated the whole progress of discovery."

"From the first discovery of the production of metals from rude ores, to the knowledge of the bleaching liquor, chemistry has been continually subservient to cultivation and improvement."

"The relations of the common metals to the bases of the alkalies and earths, and the gradations of resemblance between the bases of the earths and s, point out as probable a similarity in the constitution of all inflammable bodies; and there are not wanting experiments, which render their possible decomposition far from a chimerical idea."

"The whole work was done under conditions of great mental excitement. His cousin ,.. his assistant, relates that when he [Humphrey Davy] saw the minute globules of the quicksilver-like metal burst through the crust of potash and take fire, his joy knew no bounds; he actually danced about the room in ecstasy, and it was some time before he was sufficiently composed to continue his experiments. The rapidity with which he accumulated results after this first feeling of delirious delight had passed was extraordinary."

"Before the middle of November he had obtained most of the leading facts. In a letter dated November 13th he tells W. H. Pepys—"

"He had observed that although potash when dry is a nonconductor, it readily conducts when it becomes damp by exposure to air, and in this state "fuses and decomposes by strong electrical powers.""

"It is frequently stated that Davy was enabled to isolate the metals of the alkalis because of the large and powerful voltaic battery which he had at his disposal in the Royal Institution. This is not correct. The battery he employed was of very moderate dimensions, and not by any means extraordinary in power. It was the success he thus achieved that caused the large battery, which is probably referred to, to be constructed, by special subscription, in 1809."

"It would seem from his description of its properties that the potassium he obtained was most probably alloyed with sodium derived from impure potash. Potassium is solid up to 143° F.; but, as Davy subsequently found, an alloy of potassium and sodium is fluid at ordinary temperatures. ...When the potassium was exposed to air its metallic lustre was immediately destroyed, and it was ultimately wholly reconverted into potash by absorption of oxygen and moisture."

"The "basis" of potash at 50° F. was a soft and malleable solid with the lustre of polished silver."

"It may be converted into vapour at a temperature approaching a red-heat, and may be distilled unchanged; it is a perfect conductor of electricity and an excellent conductor of heat. Its most marked difference from the common run of metals was its extraordinarily low specific gravity."

"Although no great stress can be laid on numbers so obtained, they serve to indicate that Davy had not yet obtained the pure metal."

"The "basis" of soda is described as a white opaque substance of the lustre and general appearance of silver. It is soft and malleable, and is a good conductor of heat and electricity. Its specific gravity was found by flotation in a mixture of oil of sassafras and naphtha... It was found to fuse at about 180° F. (the real melting point of sodium is 197.5°). Its action on a number of substances—oxygen, , water, etc.—is then described, and its general behaviour contrasted with that of the "basis" of potash."

"He then enters upon some general observations on the relations of the "bases" of potash and soda to other bodies."

"He begins by again drawing attention to the various surmises which had been made respecting the true nature of potassium and sodium. Although these substances had been isolated, and in the hands of chemists for upwards of two years, their properties were so extraordinary when compared with those of the metals in general, that many philosophers hesitated to consider them as true metals."

"The general properties and chemical activities of and sodium are so very similar that as a matter of commercial production that metal which can be most economically obtained is necessarily the one most largely manufactured, and of the two that metal is sodium. To-day, sodium is made by thousands of tons, and by a process which in principle is identical with that by which it was first made by Davy, i.e., by the of fused caustic soda."

"[A]fter a series of revolutions in its manufacture, sodium, having been produced from time to time on a manufacturing scale by a variety of metallurgical methods involving purely thermal processes of reduction and distillation, entirely dissociated from electricity, we should have now got back to the very principle of the process which first brought the metal to light. And that this has been industrially possible is entirely owing to another of Davy's discoveries - possibly indeed the greatest of them all—Michael Faraday."

"Before me, stretching down to the river, was the factory where a score of workers, clad in helmets and gauntlets and swathed like so many Knights Templar, travel-stained and war-worn, their visages lit up by the yellow soda flames, and their ears half-deafened with the sound of exploding —a veritable inferno—were repeating on a Gargantuan scale the little experiment first made a century ago in the cellars of this building; turning out, day and night, hundredweights of the plastic metal in place of the little pin-heads which then burst upon the astonished and delighted gaze of Davy."

"Even before the appearance of The Sceptical Chemist there was a growing conviction that the old hypotheses as to the essential nature of matter were inadequate and misleading. ...[T]he four "elements" of the Peripatetics had become merged into the tria prima—the "salt," "sulphur," and "mercury"—of the Paracelsians. As the phenomena of chemical action became better known... the conception of the tria prinui, as understood by Paracelsus and his followers, was incapable of being generalised into a theory of chemistry. Becher, while clinging to the conception of three primordial substances as making up all forms of matter, changed the qualities hitherto associated with them. According to the new theory, all matter was composed of a mercurial, a vitreous, and a combustible substance or principle, in varying proportions, depending upon the nature of the particular form of matter. When a body was burnt or a metal calcined, the combustible substance—the terra pinguis of Becher—escaped."

"Other metals, like lead and mercury, did not appear to burn; but on heating them they gradually lost their metallic appearance, and became converted into calces. This operation was known as . In the act of burning or of calcination phlogiston was expelled. Hence metals were essentially compound: they consisted of phlogiston and a calx, the nature of which determined the character of the metal. By adding phlogiston to a calx the metal was regenerated. Thus, on heating the calx of or of with , or , or wood, metallic zinc or lead was again formed. When a candle burns, its phlogiston is transferred to the air; if burned in a limited supply of air, combustion ceases, because the air becomes saturated with phlogiston."

"Some of the alchemists had discovered that a metal gained, not lost, weight by . This was known as far back as the sixteenth century. It had been pointed out by Cardan and by Libavius. Sulzbach showed that such was the case with mercury. Boyle proved it in the case of tin, and Rey in that of lead. Moreover, as knowledge increased it became certain that Stahl's original conception of the principle of combustion as a ponderable substance he imagined, with Becher, that it was of the nature of an earth was not tenable. The later phlogistians were disposed to regard it as probably identical with . But even hydrogen has weight, and facts seemed to require that phlogiston, if it existed at all, should be devoid of weight."

"[T]he writings and labours of the alchemists were both extensive and important. ...[T]heir studies, although misdirected, were not... haphazard. The alchemists had a definite, and... logical, system of philosophy... [T]hey recognised—(1) the unity of matter; (2) the three principles—philosophical mercury, sulphur, and salt; (3) the four elements—fire, air, water, and earth; and (4) the seven metals—gold, silver, mercury, copper, , tin, and ."

"[W]hen an alchemist converted a metal into its oxide, or, as they expressed it, "made a " of it, he thought he had volatilised its mercury and fixed its sulphur. When he distilled ordinary mercury and found a solid residue in the , he called it the "sulphur" of mercury; when he found a sublimed product in the receiver (mercury bichloride), he termed it the "mercury" of mercury or "corrosive sublimate.""

"The more logical mind of Artephius Longaevus introduced a modification of this theory. He distinguished two properties in a metal—the visible and the occult. The former, comprehending its colour, lustre, extension, and other properties visible to the eye, he called its "sulphur"; the latter, comprehending its fusibility, malleability, volatility, and other properties not visible until after... special treatment, he called its "mercury.""

"The mercury of a metal... represented its lustre, volatility, fusibility, and malleability; the sulphur of the metal, its colour, combustibility, affinity, and hardness."

"The salt of the was merely a means of union between the mercury and the sulphur, just as the vital spirit in man unites soul and body. It was doubtless devised to impart a triple form to the idea, in conformity with the method of the theological schoolmen."

"At a still later date [post-16th century] it was argued that exact and natural sciences proceed by induction and deduction, and occult and spiritual sciences by analogy. Following out this line of thought the alchemists produced the following remarkable trilogy:—"

"Wootz was the first high-quality steel made anywhere in the world. According to reports of travelers to the East, the Damascus swords were made by forging small cakes of steel that were manufactured in Southern India. This steel was called wootz steel. It was more than a thousand years before steel as good was made in the West."

"Damascus steel actually consists of an extremely high-carbon cast steel, the best swords being forged in Iran from cakes of steel made in India and known as wootz."

"Original in Lithuanian: "Šiandien daugelis vakariečių nežino nieko apie Lietuvą. Neturime tokio stipraus identiteto kaip estai ar šveicarai. Tikime, kad turėdami inžinerinių kompetencijų ir pozicionuodami save kaip inžinerinę šalį tapsime lengvai atpažįstamais ir išskirtiniais""

"Translation in English: "Today, many in the West know nothing about Lithuania. We don't have as strong an identity as the Estonians or the Swiss. We believe that having engineering competences and positioning ourselves as an engineering country will make us distinctive and recognisable.""

"... Early clocks were inaccurate by as much as half an hour a day, and had to be reset frequently with the aid of a ; breakdowns were numerous. The energies of the early masters seem to have gone as much into ornamenting their clocks as into making them more precise, for the construction of human and animal automata, as well as astronomical indicators, was quite popular. Finally, in the seventeenth century, the Dutch scientist Christian Huygens created the that resulted in a vast improvement in precision. By then the clock was ingrained in the European way of thinking as the artificial model of the cyclical processes of nature, and it was ready to serve as the prototype for the mechanization of a variety of tasks that had previously been performed by hand."

"The invention of the mechanical clock, and the significant perceptual shift that attended it, provides rich and underexamined context for reading Chaucer’s works. Among social scientists it has become “textbook wisdom” that the late medieval invention of the mechanical clock transformed ideas about time."

"By a clock we understand anything characterized by a phenomenon passing periodically through identical phases so that we must assume, by the principle of sufficient reason, that all that happens in a given period is identical with all that happens in an arbitrary period."

"… We are accustomed to regard as real those sense perceptions which are common to different individuals, and which therefore are, in a measure, impersonal. The natural sciences, and in particular, the most fundamental of them, physics, deals with such sense perceptions. The conception of physical bodies, in particular of rigid bodies, is a relatively constant complex of such sense perceptions. A clock is also a body, or a system, in the same sense, with the additional property that the series of events which it counts is formed of elements all of which can be regarded as equal."

"The 1967 General Conference on Weights and Measures defined the of time, the second, based on an atomic transition—specifically, between two hyperfine levels of the ground state of cesium-133. (See Physics Today, August 1968, page 60.) Although Cs atomic clocks remain the standard, their time might be running out. Their underlying atomic transition is excited by radiation with a microwave frequency around 9 × 109 Hz, and after decades of advances, a Cs clock’s frequency can be measured with a fractional uncertainty Δν/ν0 of about one part in 1016. But clocks based on optical transitions operate at frequencies around 1014 Hz, which gives them an advantage in the push for lower uncertainty. (See the article by James Bergquist, Steven Jefferts, and David Wineland, Physics Today, March 2001, page 37.) The current record, 9.4 × 10−19, was set in 2019 by an aluminum ion–based optical atomic clock at ."

"The simplest and perhaps earliest consisted of an earthen vessel with a small hole in the bottom. This was filled with water up to a certain mark and the water was allowed to trickle out of the hole. It would empty itself in approximately the same intervals of time. It was perhaps used for limiting the length of public speeches and the like. In fact there are quite a few references in Greek and Roman writings which would indicate this to have been a fact."

"The clock, not the steam-engine, is the key-machine of the modern industrial age. For every phase of its development the clock is both the outstanding fact and the typical symbol of the machine: even today no other machine is so ubiquitous. ... In its relationship to determinable quantities of energy, to standardization, to automatic action, and finally to its own special product, accurate timing, the clock has been the foremost machine in modern technics: and at each period it has remained in the lead: it marks a perfection toward which other machines aspire."

"We do not know when men first began to use instruments which were at all similar to modern sundials. A stone fragment in a Berlin museum is thought to be the earliest known sundial, dating from about 1500 B.C. The Bible mentions what some authorities take to have been a sundial (although the meaning is by no means certain) in the days of , king of some 700 years before Christ ... About a century later the Greek philosopher and astronomer Anaximander of is said to have introduced the sundial into Greece."

"Having fixed a pole, on a level piece of ground, and having described a circle by a cord attached to the pole, one should mark the points with pegs, where the shadow of the top of the pole touches the circle. The line joining these pegs is the West to East line. Having increased the length of the cord (which is equal to the distance of the two pegs fixed in the East West line) by itself, one should provide two slings at each end of the cord. Fix the slings on the two pegs (already fixed) stretch the cord with its mid point towards the south and fix a peg at the place, where the mid point of the cord touches the ground. He should similarly proceed towards the North. The line joining these pegs will be the South to North line."

"has not been generally used as a feedstock in simple thermal cracking... because the decomposition temperature is too high and yield of useful products too low. Nevertheless... pyrolysis of methane has been used for the production of acetylene and ... Diamonds can be formed... under suitable conditions... [E]arly stages of...decomposition are... well understood... but... details of later stages are not... clear... All oxidation reactions, including oxidative pyrolysis, have been excluded."

"[A]n overall model for the simulation of pyrolysis reactors should... include the heat, momentum, s differential equations, physicochemical properties (specific heats, enthalpies, thermal conductivities, etc.) firing-box patterns, and sometimes fluid dynamic characterization (as in advanced cracking reactors)."

"Flash pyrolysis has the potential of producing maximum yields of gases and liquids from coal and organic solid wastes such as municipal refuse, tree bark, cow manure, rice hulls and grass straw using simple process equipment. The main features of the process are near ambient pressure, no requirement for added chemicals, low capital investment, high feed throughput flexibility of feedstock, variability of temperature, and minimum feed pretreatment."

"The pyrolysis of and is often the process of choice for the production of . ...Marketing of the products of from ethane pyrolysis is greatly simplified by the low yield of by-products. ...Pyrolysis of ethane and propane produces the lowest yield of byproducts, which... minimizes the size of downstream units... as the depropanizer, debutanizer, and compressors."

"Fire, as the agent for , was a favorite tool of the alchemist. Although the general prevalence... of pyrolysis has long been recognized... in the last six decades... the subject has assumed a scientific basis. Since many... data on have been incidental observations... the information is widely scattered... [T]hat ...records of many melting-point determinations are accompanied by ..."It melts with decomposition" is ...evidence ...the subject ...has ...an unorganized past."

"The transformation of a compound into another substance, or... substances, through... heat alone is... pyrolysis."

"Frequently, pyrolyses are s, but... "Pyrolysis" is... broader... [and] more concise. In "decompositions", there is... formation of at least two simpler substances. In pyrolyses... not always... [R]earrangements may be caused by heat alone. ...[F]ormation of large molecules ...is often effected by heat. Both ...are pyrolytic ...but it would be awkward to classify them as decompositions."

"Some compounds decompose at the temperature of boiling water... others require red heat. ...[C]ompounds may be stable at -40° but not at 0°. All... if caused by temperature alone, are... pyrolysis."

"[T]he great majority of pyrolyses occur at "high" temperatures, but this only means... familiarity with compounds which cannot exist at ordinary temperatures is... extremely limited."

"Occasionally... it will be helpful to note the effect of catalysts... Frequently in s, it is difficult to distinguish between the catalytic and the non-catalytic. ...Glass, or surfaces are the ones which are most used in laboratory pyrolyses. Their catalytic action is, at the best, very slight."

"In larger scale work... metallic surfaces [are usually necessary]. Wilson and Bahlke... reported that in cracking stills... -steels ("stainless" steels) [are best], or aluminum or calorized iron. Copper and some s are not satisfactory, neither... [is] ... These authors were interested in ..."

"Franz Fischer... performed... pyrogenic experiments in a tinned-iron tube, which would have failed in an iron tube because of deposition or other causes. ...[He] has shown that a ferrous sulfide inner lining [formed by passing through] in an iron tube also prevents carbon deposit[s] ..."

"The subject of wood distillation has... been treated in... this series. ...[W]ood is not a compound."

"[S]ubstances... identified among... products of wood distillation may be arranged... in a few groups of related compounds. Much of the accurate knowledge... is due to the work of Klason."

"The groups from [wood distillation] are 1. s; formic to caproic, especially . Also, furoic, angelic, s, and valerolactone. For different woods, the total acid, calculated as acetic acid, varies between 4.3 and 6.8[%]... In vacuum distillation... formic acid may be... as high as 35[%] of the acetic acid, but in ordinary distillation at atmospheric pressure, it varies from 10-20[%] of the acetic acid. Only these two acids appear to be formed in appreciable amounts. 2. Alcohols; especially and , but also isoamyl and isobutyl alcohols, and buten-3-ol-2. The content is usually... 1.3-2[%]. 3. Esters; formed by interaction of the above acids and alcohols. 4. Ketones; ... and... its homologs... [plus] small quantities of , methyl cyclopentanone, and . The acetone is not a primary [distillation] product... but is formed secondarily from the acetic acid... homologs of acetone have a similar history. 5. Aldehydes; , , methylal and dimethyl acetal, valeric aldehyde, and methyl furfural. The pentosans are... the source of the furfural and other... homologs of furan... 6. Phenols and phenol methyl ethers [only about 1 percent of the wood distilled], mostly s of di- and tris. ...These substances come largely from the . 7. [< 0.2 percent of the total] , methyl amine, and methyl pyridine... 8. , , melene, etc. 9. es; the yields of , and vary with the maximum temperature of distillation, but at 350-400° the yields from s are about 8, 4 and 1.5[%], respectively. 10. Water; the yield... varies... 22.3-27.8[%]. 11. '. ...30-45[%] ...depending on the wood, and on the maximum temperature."

"The of mineral or organic material was one of the few preparative methods available to the alchemists and the first chemists. That materials could undergo profound changes at high temperatures became a well-recognized principle... emphasized by... landmarks as the formation of by heating ferrous sulfate (copperas) described by ... Brandt's discovery of in 1669 by destructive distillation of residues from ... isolation of benzene from oil gas by Faraday in 1825 and of pyrrole from bone oil by Runge in 1834."

"s, alkalis, and many other inorganic reagents were available... in the early nineteenth century... [T]heir use often added to... descriptive organic chemistry... without clarifying structural relationships. ...[V]igorous pyrolysis of organic compounds, involving no addition of further groups, remained a common technique until about the end of the nineteenth century. ...[M]any high-temperature reactions are fragmentations which produce simple products ...[D]irect of ...carboxylic acids and ...similar decomposition of carboxylic salts by heating with lime or are... examples."

"Mitscherlich prepared benzene as early as 1834 by vigorous distillation of and lime."

"Prompted by the need of non-petroleum-based fuels, coal research has reemerged... Pyrolysis research... has gained... momentum because of its close connection to combustion, hydropyrolysis and liquification. Spectroscopic and other instrumental techniques are... producing... information about coal structure and pyrolysis mechanisms, while modeling efforts are breaking new ground in sorting out chemical and physical phenomena... [P]ostulates and assumptions of current work provide a meaningful starting point in... theoretical descriptions of greater validity and applicability."

"[T]he survey of experimental results will be confined to flash pyrolysis at the exclusion of slow pyrolysis or ."

"Flash pyrolysis poses three experimental difficulties..: (i) control and measurement of the temperature-time history of the coal particles (ii) suppression of secondary reactions (iii) quantitative collection of products."

"[M]easurement of the coal particles' temperature is not trivial. In many cases the temperature... must be calculated from a model. The other two experimental problems, the suppression of secondary reactions and the collection of products, depend on the reactor geometry and flow pattern..."

"[P]roduct distribution is the most essential information relative to the commercial utilization of pyrolysis and... sheds considerable light on reaction mechanisms."

"[P]roducts can be classified into two groups relative to the temperature dependence of the yields. , water and evolve at lower temperatures with ultimate yields that are essentially independent of temperature above 700°C. The second group... of gaseous hydrocarbons, and evolve at higher temperatures. The ultimate yield of these... continues increasing... up to 1,000°C or higher."

"In s, makes up 50-80% of the weight loss, the remaining consisting of gases, water and ."

"We are... concerned with the evolution of tar and gases during the plastic state of coal. In this... consists of two processes in series: diffusion through the molten coal to some internal surface, that of a bubble or a pore; and transport with the bubble or through the pore to the surface of the particle. The role of preexisting pores is not well understood. ...[A] certain fraction of preexisting pores (< 60 Å) collapse during pyrolysis perhaps due to effects. Pores... 60-300 Å were preserved... but one could not distinguish preexisting pores and pores generated by the evolution of bubbles. It appears likely... the major... mass transfer occurs via bubbles while preexisting bubbles play a... minor role."

"Fast pyrolysis is a new technology that shows... potential for producing... liquid... for fuel applications or as a source for... chemicals."

"Wood and biomass can be used in a variety of ways to provide energy: &bull; by direct combustion... for... heating.., steam production and hence electricity generation. &bull; by gasification to provide fuel gas... for heat, or in an engine or turbine for electricity generation. &bull; by fast pyrolysis to provide a liquid fuel... for fuel oil in... static heating or electricity generation... [and] to produce... chemicals."

"Fast pyrolysis is a high temperature process in which biomass is rapidly heated in the absence of oxygen. ...[I]t decomposes to generate mostly vapours... s and some . After cooling and condensation, a... liquid is formed which has a heating value about half... conventional . ...Fast pyrolysis ...is carefully controlled to give high yields ..."

"[E]ssential features... &bull; high heating and heat transfer rates... usually requires finely ground biomass feed &bull; carefully controlled... reaction temperature... [~]500C... vapour phase... short vapour residence typically [<]2 sec... &bull; rapid cooling of pyrolysis vapours to give... bio-oil product."

"[M]ain product, bio-oil... in yields up to 80%... with byproduct char and ... used within... process so no waste..."

"Pitch is a highly viscous residue remaining from wood pyrolysis... In the days of s, pitch was extremely valuable to seal the wood planking and for... where a tightly sticking, water-resistant material was needed."

"Eventually it was understood that the residue from a fire came from... insufficient oxygen (air) to consume the wood completely. From that... came... recognition of making charcoal deliberately by heating wood in the absence of air, or burning under severely air-limited conditions. ...[I]t was [later] realized ...volatile materials "cooked" out ...during conversion... also had valuable uses."

"Production of ... with [other] chemical products... involves pyrolysis, i.e. decomposition of compounds through application of heat."

"Because pyrolysis converts wood to highly ... charcoal... [it] is also known as . Since volatile compounds are driven off, but... residual non-volatile[s are] altered.., another name... is ."

"[T]hermal decomposition of wood begins [≈]250°C. Industrial carbonization... at ≈500°C."

"Carbonization drives off moisture... with... low molecular weight organic compounds... from extractives and... pyrolysis of ... s. Condensing vapors from carbonization produces... ... a dilute solution of up to 50 small, polar (...[i.e.] water soluble) organic compounds. ...[M]ost important ...are , , and ."

"Condensable non-aqueous ...wood tars ...[are] produced by pyrolysis and destructive distillation. Tars can be fractionated into [1] light oils, boiling below 200°C... [2] heavy tars, boiling above that... and [3] pitch. Light tars tend to be mixtures of aldehydes, carboxylic acids, esters, and ketones. Heavy oil contains... phenol derivatives; one of its uses... a wood preservative... wood tar creosote..."

"In fuel chemistry... we deal with several kinds of bond, and mixtures of... different compounds. At temperatures high enough to drive pyrolysis of... one kind of bond... other kinds... break... [I]mmediate products may undergo... subsequent reactions. As a result, pyrolysis... give[s] complex mixtures of products... of little utility if the intent is to produce a single product..."

"With... ... sealed within layers of inorganic ... long... geological processes can operate. Assuming typical s... [b]urial to 10 km would be equivalent to... 100-300°C. These... seem too low to drive... pyrolysis reactions... significant at... [≈]350°C. But... time is on our side... in geological time, tens of millions of years for catagenesis of humic kerogen."

"Like their aliphatic counterparts, the smaller phenols are also water-soluble. Phenol... has... solubility...[≈]82 g/kg water. ...Phenols are produced in coal and wood pyrolysis. Any water used in such processes becomes contaminated with phenols (as well as other compounds) and requires processing before being released... into the environment."

"The organic material in oil shales requires pyrolysis to force the catagenesis of ... This can be done above ground in kilns, or underground with the shale still in place."

"Gasification of coal... [goes] back to the 1790s at least. Before World War II, the United States... had... [≈20,000] small coal gassifiers... a popular fuel gas until... the interstate natural gas pipeline network... after World War II. Many... were simple pyrolysis or steam-carbon reactions in... crude equipment having serious environmental problems."

"Groundwater could become contaminated by organic compounds during coal pyrolysis, and by various inorganic compounds liberated as the coal is consumed. Some... pose problems for environmental quality or human health."

"To a large extent, biomass resembles gasification, with some distinctions... The kinds... considered... include wood, wood wastes (e.g. sawdust), and s. Some... grass, such as switchgrass... grown as energy crops might also serve... [R]elative to coal, biomass usually has lower calorific value... and sulfur... higher moisture, higher... and oxygen, and produces a higher yield of volatiles on pyrolysis. ...Generally biomass chars are more reactive than coal chars, so... may[be]... less and oxygen are needed for... [its] gasification."

"[L]iquids can be produced from coal by... pyrolysis... by dissolution... [i.e.] solvent extraction... or by reaction of coal with or with solvents... donating hydrogen (hydroliquification). All... constitute... coal-to-liquids (CTL) technology."

"Pyrolysis of biomass, heavy petroleum fractions, , , and usually produces some amount of liquid product. Pyrolysis... without an externally added... [source] is constrained... Pyrolysis produces liquids, but leaves a residue of carbonaceous char or coke. Usually... gases also form. The... proportions of solid, liquid, and gas depend on the... feedstock and... reaction conditions."

"[L]arge particles may not be heated uniformly... consequently pyrolysis yields are less. Heating rate is also important. During slow heat-up as... in simple... s most coals begin to decompose [≈]350-400°C. ...[L]iquid and gaseous products ...peak ...[≈]425-475°C. This phase of pyrolysis ends ...[≈]500-550°C. ...[V]ery rapid heating [e.g.] in entrained flow gasifiers ...quickly by-passes this stage, so... evolution of liquids is nil."

"pyrolysis is... complicated... by the fact... primary pyrolysis products... are... able to react among themselves... with ... from the moisture in the coal... with char or coke, or... several of these. The products... often called secondary... may differ... from the primary... Primary products can be studied... if... quench[ed]... rapidly or... [fed] directly into a suitable... instrument... [e.g.] a gas chromatograph."

"In industrial practice... design of the pyrolysis reactor affects... composition of liquid products, because... [it] determines how long... primary products are exposed to pyrolysis temperatures..."

"Commercial... applications of pyrolysis have been to produce... a eous fuel... or a char... Liquids... directly are unsuitable... as fuels... Some... downstream operations would be required... Nevertheless, low-temperature s can be refined... into or ."

"Possibly, future events on the world energy scene will revive interest... Pyrolysis offers... simplicity of process and equipment design relative to gasification and hydroliquification. ...[But] competing technologies usually provide high yields of a single type... gas, liquid or solid... which may offset the added complexity and cost..."

"[R]ules change when an external supply of is... available. Hydropyrolysis, i.e. pyrolizing coal in a hydrogen atmosphere, increases the yields of liquids and gases... [H]ydrogen... stabilizes radicals by hydrogen capping before... termination by recombination reactions that... lead to char... Despite this advantage... hydropyrolysis has never been commercialized."

"[S]tories... about "free oil" from coal pyrolysis, often in reference to a low-temperature ... by ... [≈]80 years ago. Many... accompanied by... conspiracy theories... The , and similar carbonization processes... produce a liquid. Presumably, a... clever accountant could figure out how this... could be "free," provided... markets existed for... large amounts of char and gas produced at the same time, and... could be sold... high enough to compensate for giving away the liquid. Then there's the cost of refining the low-temperature into specification-grade marketable fuel..."

"Often... terms carbonization and pyrolysis are used almost interchangeably. Pyrolysis has the broader meaning: breaking... molecules by... heat or thermal energy. ...[P]yrolysis ...could be run to make gases and liquids rather than solids as the primary product. ... narrowly defined, refers to conversion of a starting material into carbon, or a carbon-rich solid. ...[One can] pyrolyze a hydrocarbon feedstock for the purpose of carbonization, but carbonization is not... pyrolysis by another name. Carbonization can be effected without heat as... primary driving force... Carbonization driven by thermal energy usually requires >500°C."

"Pyrolysis of an oil product or natural gas leads to thermal blacks. ...Acetylene black is made by of acetylene. ...[P]reheated to 800°C ...acetylene is introduced and... because the pyrolysis is exothermic, the temperature... reaches ~2500°C. formation takes place... [800°C-~]2000°C. ...2000-2500°C induces partial of the carbon black. Due to... partial graphitic nature, acelylene blacks have... applications where good [electrical and thermal] conductivity... or... very low chemical reactivity is desirable."

"Almost all pyrolysis reactions are endothermic because they involve breaking bonds in stable compounds."

"Pyrolysis of fossil or s... is... accompanied by char formation. In some cases, this is the point... being an example. ...[I]f pyrolysis were ...done to make gaseous or liquid fuels, and no... market existed for the char, it would be possible to... bury the char... [which] would sequester carbon..."

"[P]yrolysis of biomass to produce char for carbon sequestration has multiple benefits... The product... is... called or Agri-char, sometimes (dark earth)... Trials in Australia have produced a doubling... or tripling of crop production... [C]har is likely to retain some... , , and ... Biochars are very porous... taking up and holding moisture. ...By ...stimulating plant growth, biochar has a double impact... First, it... sequesters carbon. Second... increased growth of plants removes CO, from the atmosphere..."

"Annual production of worldwide amounts to some four gigatonnes. A pyrolysis... that yielded only ten percent could produce enough to fertilize some forty million hectares..."

"s are... ancient technology. Biomass pyrolysis would be "low tech." Farmers could build and install their own... Alternatively, a biochar kiln could be mounted on... a truck... and taken from farm to farm..."

"A comprehensive program..: harvesting and shipping biomass to a centralized biomass or plant within the economically limiting radius, and beyond... converting biomass to biochar in small, decentralized units."