Mathematicians From France

"Carnot’s memoir remained for a long time unappreciated, and it was not until use was made of it by William Thomson (now Lord Kelvin), in 1848, to establish an absolute scale of temperature, that the merits of the method proposed in it were recognized."

"Thomson] found that Carnot’s proposition could no longer be proved by denying the possibility of “the perpetual motion,” and was led to lay down a second fundamental principle to serve in the demonstration. This principle [published in Thomson's memoir of March, 1851] is now called the Second Law of Thermodynamics."

"Love is almost the only passion that the good man may avow. It is the only one which accords with delicacy."

"If God is absolutely good, why should He punish the sinner for all eternity, since He does not lead him to good, or give him an example?"

"[F]rom Carnot's point of view, it is evident that the motive power of heat depends upon its being transferred from one body to another through the medium by whose change of volume or form the external mechanical effect is produced, as this medium is supposed to remain at the end of the operation in precisely the same state as at the commencement. He gives as analogous the instance of work derived from water falling from a higher to a lower level."

"A religion suited to the soul and preached by men worthy of respect would exercise the most salutary influence upon society and customs."

"It is but bare justice... to acknowledge that Carnot himself was by no means satisfied with the caloric hypothesis and that he insinuates... more than a mere suspicion of its correctness."

"When discussion degenerates into dispute, be silent; this is not to declare yourself beaten."

"Never direct an argument against any one. If you know some particulars against your adversary, you have a right to make him aware of it to keep him under control, but proceed with discretion, and do not wound him before others."

"It would seem... that heat set free should be attributed to the friction of the molecules of the metal, which change place relatively to each other, that is, the heat is set free just where the moving force is expended. ...We may also cite... the heat produced by the extension of a metallic rod just before it breaks... the greater the elongation before rupture, the more considerable is the elevation of temperature."

"How much modesty adds to merit! A man of talent who conceals his knowledge is like a branch bending under a weight of fruit."

"Listen attentively to your interlocutor, and so prepare him to listen in the same way to your reply, and predispose him in favor of your arguments."

"Employ only expressions of the most perfect propriety."

"Show neither passion nor weariness in discussion."

"Why try to be witty? I would rather be thought stupid and modest than witty and pretentious."

"Speak little of what you know, and not at all of what you do not know."

"Question thyself to learn what will please others."

"Heat is simply motive power, or rather motion which has changed form. It is a movement among the particles of bodies. Wherever there is destruction of motive power there is, at the same time, production of heat in quantity exactly proportional to the quantity of motive power destroyed. Reciprocally, wherever there is destruction of heat, there is production of motive power."

"Speak to every one of that which he knows best. This will put him at his ease, and be profitable to you."

"Never turn to the past unless to enlighten the future. Regrets are useless."

"Yield frequently to the first inspiration. Too much meditation on the same subject ends by suggesting the worst part, or at least causes loss of precious time."

"Carnot considered that the steam engine was analogous to another prime mover, the water wheel. The analogy, and the upon which it was based, led Carnot to the incorrect conclusion that no heat was lost, or converted into mechanical energy during the operation of the steam engine. He thought that the same quantity of heat was given out by the boiler at the higher temperature as was received by the condenser at the lower temperature. However, the analogy led him also to the fruitful conception that the amount of energy produced... was solely dependent, in principle, upon the temperature difference between the boiler and the condenser and the amount of heat which passed from the one to the other. Thus it appeared that all heat engines in general, would have the same efficiency if they worked within the same temperature levels. He substantiated this... Carnot's principle, by pointing out that would be possible if it were not true. If two perfect heat engines operating between the same temperature levels did not have the same efficiency, it would be possible for the more efficient... to drive the less efficient engine backwards, pumping heat from the lower to the higher temperature, thus leaving the thermal conditions unchanged and yet generating a continuous excess of energy."

"One should never feign a character that he has not, or affect a character that he cannot sustain."

"Abstain from all pleasantry which could wound."

"Men desire nothing so much as to make themselves envied."

"On January 16, 1793, the in Paris sentenced to death. Among those who took the fatal decision was... Lazare Carnot... [who] had a passion for the great Persian poet Saadi Shirazi... Carnot names his first son after Saadi. Sadi Carnot is thus born out of poetry and rebellion. As a young man, he develops a passion for those steam engines... beginning to transform the world... In 1824, he writes... "," in which he seeks to understand the theoretical basis of... these machines. The little treatise is packed with mistaken assumptions: he imagines that heat is a concrete entity... fluid that produces energy by "falling" from hot things to cold, just as... a waterfall... But it contains a key idea: that steam engines function... because the heat passes from hot to cold."

"We shall have [a complete theory] only when the laws of Physics shall be extended enough, generalized enough, to make known beforehand all the effects of heat acting in a determined manner on any body."

"The phenomenon of the production of motion by heat has not been considered from a sufficiently general point of view. We have considered it only in machines... [for which] the phenomenon is... incomplete. It becomes difficult to recognize its principles and study its laws. ...[T]he principle of the production of motion by heat... must be considered independently of any mechanism or... particular agent. It is necessary to establish principles applicable not only to steam-engines but to all imaginable heat-engines, whatever the working substance and whatever the method by which it is operated."

"The production of motion in steam-engines is always accompanied by... the re-establishing of equilibrium in the caloric; that is, its passage from a body in which the temperature is more or less elevated, to another in which it is lower."

"Iron and heat are... the supporters, the bases, of the mechanic arts."

"What happens... in a steam-engine... ? The caloric developed in the furnace by the effect of the combustion traverses the walls of the boiler, produces steam, and in some way incorporates itself with it. The latter carrying it away, takes it first into the cylinder, where it performs some function, and from thence into the condenser, where it is liquefied by contact with the cold water... [T]he cold water of the condenser takes possession of the caloric... It is heated by the intervention of the steam as if it had been placed directly over the furnace. The steam is here only a means of transporting the caloric."

"To take away to-day from England her steam-engines would be to take away at the same time her coal and iron. It would be to dry up all her sources of wealth, to ruin all on which her prosperity depends, in short, to annihilate that colossal power."

"Plan in the morning the work of the day, and reflect in the evening on what has been done."

"Carry when walking a book, and a note-book to preserve the ideas, and a piece of bread in order to prolong the walk if need be."

"Suffer slight disagreeables without seeming to perceive them, but repulse decisively any one who evidently intends to injure or humiliate you."

"For a considerable portion of the present century, Davy's discoveries about heat were neglected, or only casually mentioned; but this was of comparatively little consequence, as their early reception might have kept back for a time the grand developments which must next be mentioned—immense strides in the theoretical and mathematical treatment of the subject, and to a considerable extent independent of the nature of heat. These are due to Fourier and Sadi Carnot, and it may well be said that it is in great part attributable to their remarkable works that the true theory of heat... received so rapidly its present enormous development. ...Very different in form and object from the systematic treatise of Fourier, is the profound and valuable essay of Sadi Carnot, Reflexions sur la Puissance Motrice du Feu, published in 1824. The author endeavours to determine how it is that heat produces mechanical effect..."

"The maximum of motive power resulting from the employment of steam is also the maximum of motive power realizable by any means whatever.1878"

"Nature, in providing us with combustibles on all sides, has given us the power to produce, at all times and in all places, heat and the impelling power which is the result of it. To develop this power, to appropriate it to our uses, is the object of heat-engines."

"There is almost as great a distance between the first apparatus in which the expansive force of steam was displayed and the existing machine, as between the first raft that man ever made and the modern vessel."

"Steam navigation... tends to unite the nations of the earth as inhahitants of one country. ...is not this the same as greatly to shorten distances?"

"Notwithstanding the work of all kinds done by steam-engines... their theory is very little understood, and the attempts to improve them are still directed almost by chance."

"Savery, Newcomen, Smeaton, the famous Watt, Woolf, Trevithick, and some other English engineers, are the veritable creators of the steam-engine."

"Form resolutions in advance in order not to reflect during action. Then obey thyself blindly."

"The promptitude of resolutions most frequently accords with their justice."

"Vary the mental and bodily exercises with dancing, horsemanship, swimming, fencing with sword and with sabre, shooting with gun and pistol, skating, the sling, stilts, tennis, bowls; hop on one foot, cross the arms, jump high and far, turn on one foot propped against the wall, exercise in shirt in the evening to get up a perspiration before going to bed; turning, joinery, gardening, reading while walking, declamation, singing, violin, versification, musical composition; eight hours of sleep; a walk on awakening, before and after eating; great sobriety; eat slowly, little, and often; avoid idleness and useless meditation."

"Adopt good habits when I change my method of life."

"Self-possession without self-sufficiency. Courage without effrontery."

"Make intimate acquaintances only with much circumspection; perfect confidence in those who have been thoroughly tested. Nothing to do with others."

"No useless discourse. All conversation which does not serve to enlighten ourselves or others, to interest the heart or amuse the mind, is hurtful."

"Heat can evidently be a cause of motion only by virtue of the changes of volume or of form which it produces in bodies."