"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 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."

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

"[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..."

"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."

"[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..."

"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."

"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 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 ..."

"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."

"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."

"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."

"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."

"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."

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

"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."

"When the master-builder has taken up the work concerned, he is to re-establish securely any place where the fortification has fallen into ruins. Let him reinforce and also rebuild it."

"The Muslim invaders were necessarily impressed by Indian architecture and sculpture, expressing as they do foreign religious emotions in terms of images and emblems. What they saw at Delhi, and the other cities of India, which they attacked, was absolutely foreign to them. Yet when they came to raise their own religious buildings, they were not averse to using the spoils of their temples… The ruthless desecration and makeshift conversion of Indian temples into Mosques has led many scholars to regard Indo-Muslim architecture as nothing more than a local variety of hybrid nature. In point of fact, these early Indian mosques which were compiled from Brahamanical fragments, such as the Deval Masjid at Bodhan near Hyderabad, have no direct bearing on the general development of Mosque architecture in India.… On the other hand the use of the spoils of non-Muslim ruins was a widely recognised feature in early Muslim architecture…"

"Aurangzeb was a misfortune for Mogul and Indian art. Dedicated fanatically to an exclusive religion, he saw in art nothing but idolatry and vanity. Already Shah Jehan had prohibited the erection of Hindu temples; Aurangzeb not only continued the ban, but gave so economical a support to Moslem building that it, too, languished under his reign. Indian art followed him to the grave."

"The beautiful Kutb-Minar exemplifies the transition. It was part of a mosque begun at Old Delhi by Kutbu-d Din Aibak; it commemorated the victories of that bloody Sultan over the Hindus, and twenty-seven Hindu temples were dismembered to provide material for the mosque and the tower. After withstanding the elements for seven centuries the great minaret—250 feet high, built of fine red sandstone, perfectly proportioned, and crowned on its topmost stages with white marble—is still one of the masterpieces of Indian technology and art. In general the Sultans of Delhi were too busy with killing to have much time for architecture, and such buildings as they have left us are mostly the tombs that they raised during their own lifetime as reminders that even they would die. The best example of these is the mausoleum of Sher Shah at Sasseram, in Bihar; gigantic, solid, masculine, it was the last stage of the more virile Moorish manner before it softened into the architectural jewelry of the Mogul kings."

"The final triumph of Indian architecture came under the Moguls. The followers of Mohammed had proved themselves master builders wherever they had carried their arms—at Granada, at Cairo, at Jerusalem, at Baghdad; it was to be expected that this vigorous stock, after establishing itself securely in India, would raise upon the conquered soil mosques as resplendent as Omar’s at Jerusalem, as massive as Hassan’s at Cairo, and as delicate as the Alhambra. It is true that the “Afghan” dynasty used Hindu artisans, copied Hindu themes, and even appropriated the pillars of Hindu temples, for their architectural purposes, and that many mosques were merely Hindu temples rebuilt for Moslem prayer;119 but this natural imitation passed quickly into a style so typically Moorish that one is surprised to find the Taj Mahal in India rather than in Persia, North Africa or Spain."

"…the very grandeur of the Mogul buildings is oppressive. Europe has its monuments of sun-kings, its Louvres and its Versailles. But they are part of the development of a country’s spirit; they express the refining of a nation’s sensibility; they add to the common, growing stock. In India these endless mosques and rhetorical mausolea, these great palaces speak only of a personal plunder and for a country with an infinite capacity for being plundered. The Mogul owned everything in his dominions; and this is the message of the Mogul architecture. I know only one building in England with this quality of dead-end personal extravagance…the Blenheim. Imagine England as a country of Blenheims, continually built, destroyed and rebuilt over five hundred years, each a gift of the nation and seldom for services rendered…leaving at the end no vigorous nation…no principle beyond that of personal despotism. The Taj Mahal is exquisite…But in India it is a building wastefully without function; it is only a despot’s monument to a woman, not of India, who bore a child every year for fifteen years. It took twenty-two years to build; and the guide will tell you how many millions it cost."

"Furthermore, we are instructed, when we do come across instances of temple destruction, as in the case of Aurangzeb, we have to be circumspect in inferring what has happened and why.... the early monuments – like the Quwwat-ul-Islam mosque in Delhi – had to be built in ‘great haste’, we are instructed...Proclamation of political power, alone! And what about the religion which insists that religious faith is all, that the political cannot be separated from the religious? And the name: the Quwwat-ul-Islam mosque, the Might of Islam mosque? Of course, that must be taken to be mere genuflection! And notice: ‘available materials were assembled and incorporated’, they ‘clearly came from Hindu sources’ – may be the materials were just lying about; may be the temples had crumbled on their own earlier; may be the Hindus voluntarily broke their temples and donated the materials? No? After all, there is no proof they didn’t! And so, the word ‘plundered’ is repeatedly put within quotation marks! In fact, there is more. The use of such materials – from Hindu temples – for constructing Islamic mosques is part of ‘a process of architectural definition and accommodation by local workmen essential to the further development of a South Asian architecture for Islamic use’. The primary responsibility thus becomes that of those ‘local workmen’ and their ‘accommodation’. Hence, features in the Qutb complex come to ‘demonstrate a creative response by architects and carvers to a new programme’. A mosque that has clearly used materials, including pillars, from Hindu temples, in which undeniably ‘in the fabric of the central dome, a lintel carved with Hindu deities has been turned around so that its images face into the rubble wall’ comes ‘not to fix the rule’. ‘Rather, it stands in contrast to the rapid exploration of collaborative and creative possibilities – architectural, decorative, and synthetic – found in less fortified contexts.’ Conclusions to the contrary have been ‘misevaluations’. We are making the error of ‘seeing salvaged pieces’ – what a good word that, ‘salvaged ’: the pieces were not obtained by breaking down temples; they were lying as rubble and would inevitably have disintegrated with the passage of time; instead they were ‘salvaged ’, and given the honour of becoming part of new, pious buildings – ‘seeing salvaged pieces where healthy collaborative creativity was producing new forms’."

"The oldest of the Mosques in Malwa is the Kamal Maula Masjid which was built in Dhar in AH 803/AD 1400. Both this Mosque and the slightly later Jami or Lat Masjid are clearly adaptations of ruined Hindu temple material… The transfer of the capital from Dhar to Mandu by Dilwar Khan in AH 794/AD 1392, marks a new phase in the development of Mosque architecture in Malwa. The Mosque built by him in C. AH 808/AD 1405-06 is oblong in ground plan, the western side being formed by the liwan. Its roof is supported by Hindu pillars…"

"Like all other provinces of India, the Deccan, also, witnessed the growth of a distinguished school of Muslim architecture. Its early phase is also, characterized by the adaptation of local temples, for the purpose of Muslim congregational prayer, as exemplified by the Deval Mosque of Bodhan in Nizamabad, near Hyderabad, dated AD 1318, which was formerly a Hindu shrine…"

"It is said that the star-shaped Jaina Temple built in the Chalukya style at Bodhan in the 9th or 10th century was, also, transformed into a Mosque during the reign of Muhammad Tughlaq (AH 726-52/AD 1325-51).… The Mosque of Qutb al-Din Mubarak Khalji at Daulatabad, dated AH 718/AD 1318, is probably the earliest surviving Muslim structure in the Deccan. It is a square, 260 feet each way, assembled into the usual orthodox plan out of destroyed Hindu pillars, brackets, and beams…"

"The Jami Masjid of Badaun, also built by Iletmish is one of the largest mosques in India. Following the traditional courtyard plan, it also utilizes Hindu temple pillars. The entrance arches of the gateways leading into the courtyard of the Mosque presumably recall those in the great Mosques at Delhi and Ajmer…"

"“…To Iletmish we owe some of the finest Muslim works in India. The Arhai din ka-Jhopra began by Qutab al-Din in AD 1198-99, was also completed by him. Tod had said of it that it was ‘one of the most perfect as well as the most ancient monuments of Hindu architecture’, on the evidence of certain four-armed figures to be seen on the pillars… “The Ajmer Mosque resembles the Delhi Mosque in its use of pre-Muslim materials as well as in its courtyard plan, arched screen, columnar liwan and riwags and use of reconstructed Hindu corbelled domes. All these features, except the fragments of Hindu and Jain carvings used in the work are essentially Islamic. The Ajmer Mosque indicates a further improvement in Mosque design… As Sardar puts it, ‘These pillars have a greater height than those at the Kutub, and are more elegant in their sculpture and general appearance than the converted Mosques in Malwa and Ahmedabad.’”419"

"“…Delhi was the source of artistic inspiration for all the later provincial schools of Indo-Muslim architecture. Codrington remarks, ‘At Delhi, the Kutb-ul-Islam marks the beginning of Islamic architecture in India.’ This formative phase of Mosque architecture in India began with the random utilization of temple spoils, Hindu architraves, corbelled ceilings, kumbha pillars with hanging bell-and-chain motifs, which were organised to fulfil the needs of congregational prayer. It is said that the columns of twenty-seven Hindu and Jaina temples were utilized in the great Mosque, at Delhi, rightly called the ‘Might of Islam’. It was built by Qutb-al-Din Aybak in AH 587/AD 1191-92 on an ancient pre-Muslim plinth. …Originally there were five domes in the liwan all compiled of Hindu fragments, as is evident from their corbelled interiors…"

"…During the Husain Shahi period the stone cutter’s art was thoroughly practised and perfected, as walls of gates and mosques were adorned with stone, either quarried from Rajmahal hills or obtained from some existing buildings… …The British Museum, London, has in its collection two sculptured pieces from Bengal, namely, the seated Buddha figure (Pl. XLIIa) and the image of Brahmani. Both these images have on their obverse exquisitely carved diaper work of unmistakable Muslim workmanship. The Indian Museum, Calcutta, has a stone slab carved on the one side with the image of Durga, destroying Mahisha or Buffalow-demon, and on the reverse arabesque. The panel consisting of a scalloped arch with a lotus rosette on each of its sides, surrounded by richly foliated devices, is undoubtedly a Muslim work... The Muslim calligraphers did not feel any scruple to utilize fragments of Hindu or Jaina sculpture in carving out beautiful inscriptions in elegant Naskh, Thulth and Tughra, keeping the images inside the wall…"

"Creighton drew the sketches of a few Hindu sculptures which were evidently used in the Chhoto Sona Masjid at Gaud. These are the image of Sivani, the consort of Siva, Varahaavatara or Vishnu in the form of a Boar, Brahmani, consort of Brahma. In the British Museum there are a few images of Hindu and Buddhist character, such as the Brahmani, sketched by Creighton, and the seated Buddha figure. The Muslim builders out of sheer expediency felt no scruple to use these fragments in their mosques by concealing the carved sides into the wall and utilizing the flat reverse side of these black basalts for arabesque design in shallow carvings. Piecemeal utilization of Hindu sculptures were also to be seen in the earlier monuments, such as, the Mosque and Tomb of Zafar Khan at Tribeni, the Mosque at Chhoto Pandua, the Adina Masjid at Hazrat Pandua, etc. ... Cunningham found in the pulpit of the Adina Masjid ‘a line of Hindu sculpture of very fine bold execution.’ Innumerable Hindu lintels, pillars, door-jambs, bases, capitals, friezes, fragments of stone carvings, dadoes, etc., have been utilized in such a makeshift style as to render ‘improvisation’ well-nigh impossible. In many cases as observed in the Quwwat al-Islam at Delhi and the Arhai-din-ka-Jhopra Mosque at Ajmer, pillars were inverted, joining the base with capitals, suiting neither pattern nor size. Still there is no denying the fact that Hindu materials were utilized, yet it would be far-fetched to say that existing Hindu temples were dismantled and converted by improvisation into mosques as observed in the early phase of Muslim architecture in Indo-Pak sub-continent. The ritual needs and structural properties of the Hindus and the Muslims are so diametrically opposite as to deter any compromise and, therefore, the early Muslim conquerors of Bengal said their prayer in mosques built out of the fragments of Hindu materials in the same way as their predecessors did at Delhi, Ajmer, Patan, Janupur, Dhar and Mandu, and elsewhere. In the event [absence?] of any complete picture of pre-Muslim Hindu art as practised in Gaud and Hazrat Pandua, it is an exaggeration to hold the view after Saraswati that ‘indeed, every structure of this royal city (Hazrat Pandua) discloses Hindu materials in its composition, thus, disclosing that no earlier monument was spared.”"

"The Indian Museum, Calcutta, as well as the Bangiya Sahitya Parishad Museum, Calcutta, acquired a large number of architectural objects from the ancient sites of Bengal, particularly, Gaud, Hazrat Pandua, Bagerhat, Hughli, Rajshahi, Dinajpur and elsewhere. Besides freshly quarried basalts, a large quantity of locally available building materials was employed by the architects of Gaud, Hazrat Pandua and elsewhere. Ravenshaw’s unwarranted observation that ‘Though it (Hazrat Pandua) cannot boast of such antiquity as Gaud, its remains afford stronger evidence than those of the latter city of its having been constructed mainly from the materials of Hindoo buildings’, has been brushed aside by Westmacott, who thinks that Hazrat Pandua is older than Gaud. One of the strongest advocates of the Indianized form of Muslim structures is Havell, who is too intolerant to allow any credit to the Muslim builders for the use of radiating arches, domes, minarets, delicate relief works. He maintains that the central mihrab of the Adina Masjid (Pl. III) at Hazrat Pandua is so obviously Hindu in design as hardly to require comments. While Havell writes that ‘The image of Vishnu or Surya has trefoil arched canopy, symbolizing the aura’ of the god, of exactly the same type as the outer arch of the mihrab, Beglar says that the Muslims delighted in ‘placing the sanctum of his orthodox cult (in this case the main prayer niche) on the spot, where hated infidel had his sanctum’. Saraswati is even more emphatic on this point when he contends, ‘An examination of the stones used in the construction of the Adina Masjid (one of them bearing a Sanscrit inscription, recording merely a name of Indranath, in the character of the 9th century AD) and those lying about in heaps all round, reveals the fact, which no careful observer can deny, that most of them came from temples that once stood in the vicinity.’ Ilahi Bakhsh, Creighton, Ravenshaw, Buchanan-Hamilton, Westmacott, Beglar, Cunnigham, King, and a host of other historians and archaeologists bear glowing testimony to the utilization of non-muslim materials (Fig. 3b & Pl. V), but none of them ventured to say that existing temples were dismantled and materials provided for the construction of magnificent monuments in Gaud and Hazrat Pandua."

"Creighton says, ‘It appears to have been the general practice of the Muhammadan conquerors of India, to destroy all the temples of the idolaters, and to raise Mosque out of their ruins.’ The statement is of course a gross exaggeration, for innumerable contemporary Hindu and Buddhist temples still exist in the cities of India once conquered by the Muslims. ‘Abid ‘Ali seems to have carried the observation of Creighton further when he remarks, ‘It seems to the writer that the builder of the Mosque [Chhoto Sona Masjid at Gaud] had collected the stones containing the figure of the Hindu gods from the citadel of Gaur where temples must have existed in the time of the earlier Hindu kings.’ (...) In the event of a prodigious abundance of Hindu temple building material scattered all over the province, it is difficult to pin-point the provenance of each stray sculptured piece used in the mosques of Gaud and Hazrat Pandua. The existence of any Hindu temple in the citadel or outside Gaud as ‘Abid ‘Ali tells us, is as difficult to prove as to obviate the fact that no material was taken from Devikot or Bannagar in Dinajpur. Contradicting the views of ‘Abid ‘Ali, Stapleton says, ‘On the other hand from Manrique’s statement that in 1641, he saw figures of idols standing in niches surrounded by carved grotesques and leaves in some stone reservoirs in Gaur, it is possible that except during periods of persecution the Muhammadan Kings of Gaur allowed idols and Hindu temples to remain unmolested in their capital.’ Although examples of the use of Hindu material are not scarce, as proved by the discovery of three sculptured figures from Mahisantosh with Muslim ornament on the reverse side, now in the Varendra Research Society Museum, it would be wrong to say after Creighton that all the Hindu temples were desecrated by the Muslims to procure building material… (...) One of the strongest advocates of the Indianized form of Muslim structures is Havell, who is too intolerant to allow any credit to the Muslim builders for the use of radiating arches, domes, minarets, delicate relief works. He maintains that the central mihrab of the Adina Masjid at Hazrat Pandua is so obviously Hindu in design as hardly to require comments. While Havell writes that ‘The image of Vishnu or Surya has trefoil arched canopy, symbolizing the aura’ of the god, of exactly the same type as the outer arch of the mihrab, Beglar says that the Muslims delighted in ‘placing the sanctum of his orthodox cult (in this case the main prayer niche) on the spot, where hated infidel had his sanctum’. Saraswati is even more emphatic on this point when he contends, ‘An examination of the stones used in the construction of the Adina Masjid (one of them bearing a Sanscrit inscription, recording merely a name of Indranath, in the character of the 9th century AD) and those lying about in heaps all round, reveals the fact, which no careful observer can deny, that most of them came from temples that once stood in the vicinity.’ Ilahi Bakhsh, Creighton, Ravenshaw, Buchanan-Hamilton, Westmacott, Beglar, Cunnigham, King, and a host of other historians and archaeologists bear glowing testimony to the utilization of non-muslim materials, but none of them ventured to say that existing temples were dismantled and materials provided for the construction of magnificent monuments in Gaud and Hazrat Pandua..."

"The early formative phase of Indo-Muslim architecture, marked by the adaptation of Hindu, Buddhist or Jaina temples, is illustrated by the oldest Mosques at Delhi, Bengal, Jaunpur, Daulatabad, Patan, etc. In Malwa, also, spoils of Hindu temples were used…"

"Just as later Mughal painting is a harmonious blend of Persian and Indian artistic tradition, so the Indo-Muslim architecture of Delhi and Ajmer is a blend. In the Quwwat al-Islam at Delhi and the Arhai din-ka-Jhopra at Ajmer, existing remains bear unmistakable evidence that they were not merely compilations, but the distinctive, planned works of professional architects…"

"Although constructed of destroyed Hindu temples, the Mosques at Old Delhi and Ajmer once and for all set the fashion to be followed by later mosques in Muslim India…"

"A place you put people... to forget about 'em!"

"Witness if you will a dungeon, made out of mountains, salt flats and sand that stretch to infinity. The dungeon has an inmate: James A. Corry. And this is his residence: a metal shack. An old touring car that squats in the sun and goes nowhere - for there is nowhere to go. For the record let it be known that James A. Corry is a convicted criminal placed in solitary confinement. Confinement in this case stretches as far as the eye can see, because this particular dungeon is on an asteroid nine million miles from the Earth. Now witness if you will a man's mind and body shrivelling in the sun, a man dying of loneliness."

"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."

"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?"

"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 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."

"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."

"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."

"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."