Nicolas Léonard Sadi Carnot

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

"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."

"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?"

"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."

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

"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."

"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."

"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 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."

"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."

"[W]e have just described the re-establishment of equilibrium in the caloric, its passage from a... heated body to a cooler one."

"The production of motive power is then due... not to an actual consumption of caloric, but to its transportation from a warm body to a cold body... to its re-establishment of equilibrium..."

"[T]he production of heat alone is not sufficient to give birth to the impelling power: it is necessary that there should also be cold; without it, the heat would be useless."

"[I]f we should find about us only bodies as hot as our furnaces, how can we condense steam? What should we do with it if once produced?"

"Wherever there exists a difference of temperature... it is possible to have also the production of impelling power. ...All substances in nature can be employed for this purpose, all are susceptible of changes of volume, of successive contractions and dilatations, through the alternation of heat and cold. All are capable of overcoming in their changes of volume certain resistances... A solid... A liquid... An aeriform fluid... If it is enclosed in an expansible space, such as a cylinder provided with a piston, it will produce movements of great extent. Vapors of all substances capable of passing into a gaseous condition, as of , of mercury, of , etc., may fulfil the same office as vapor of water. ...Most of these... have been proposed, many even have been tried, although... without remarkable success."

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

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

"[W]hen a body has experienced any changes, and when after a certain number of transformations it returns to precisely its original state, that is, to that state considered in respect to density, to temperature, to mode of aggregation—let us suppose, I say, that this body is found to contain the same quantity of heat that it contained at first, or else that the quantities of heat absorbed or set free in these different transformations are exactly compensated. This fact has never been called in question. It was first admitted without reflection, and verified afterwards in many cases by experiments with the . To deny it would be to overthrow the whole theory of heat to which it serves as a basis. For the rest, we may say in passing, the main principles on which the theory of heat rests require the most careful examination. Many experimental facts appear almost inexplicable in the present state of this theory."

"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."

"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."

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

"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."

"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."

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

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

"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."

"Question thyself to learn what will please 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."

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

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

"Abstain from all pleasantry which could wound."

"Employ only expressions of the most perfect propriety."

"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."

"Show neither passion nor weariness in discussion."

"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."

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

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

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

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

"Egotism is the most common and most hated of all vices. Properly speaking, it is the only one which should be hated."

"The pleasures of self-love are the only ones that can really be turned into ridicule."

"I do not know why these two expressions, good sense and common sense, are confounded. There is nothing less common than good sense."

"The strain of suffering causes the mind to decay."

"It must be that all honest people are in the galleys; only knaves are to be met with elsewhere."

"I rejoice for all the misfortunes which might have happened to me, and which I have escaped."

"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."