Nicolas Léonard Sadi Carnot

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

“Adopt good habits when I change my method of life.”

“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.”

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

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

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

“[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?”

“[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.”

“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...”

“[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 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.”

“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.”

“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.”

“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?”

“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.”

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

“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.”