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| 1813 portrait of Sadi Carnot, at the age of 17 in his Polytecnique uniform, by Louis Boilly. | ||
| French | Carnot | manuscript notes (c.1927) | English | Thurston (1880) translation |
| “La Chaleur n'est autre que la puissance motive, ou plutót, que le mouvement qui a changé de forme. C'est un mouvement dans les particules des corps. Partout ou il y a destruction de puissance motive, il y a, en même temps, production de chaleur en quantité précisément proportionelle à la quantité de puissance motive détruite. Réciproquement, partout on ily a destruction de chaleur, il y a production de puissance motive.” On peut donc poser en thèse générale que la puissance motive est en quantité invariable dans la nature, qu’elle n'est jamais, a proprement parler, détruite. A la vérité, elle change de forme, c'est-a-dire qu’elle produit tantôt un genre de mouvement, tantôt un autre; mais jamais elle n'est anéantie.” | “Heat is nothing else than motive power (energy), or rather, a motion which has changed its form. It is a motion of the molecules of bodies. Whenever motive power is destroyed, there is, at the same time, a production of heat in quantity precisely proportional to the quantity of power destroyed. Reciprocally, wherever there is destruction of heat, there is production of power of motion. We may then state as a general law, that energy is, in nature, invariable in amount; that is, is never, properly speaking, either created or destroyed. In fact, it changes form; that is, it causes sometimes one kind of motion, sometimes another; but it is never destroyed.” |
| English | Google translation | English | Fox (1880) translation |
| "Heat is none other than motive power, or rather, movement that has changed form. It is a movement in the particles of bodies. Wherever there is a destruction of motive power, there is at the same time a production of heat in proportion to the quantity of motive power destroyed. Conversely, everywhere there is a destruction of heat, there is a production of motive power. It may therefore be posited in general theory that motive power is in invariable quantity in nature, that it is never, strictly speaking , destroyed. In truth, it changes its form, that is to say, it produces sometimes a kind of movement, sometimes another; but it is never destroyed." | “Heat is nothing but motive power, or rather motion, which has changed form. It is motion of the particles of bodies. Whenever motive power is destroyed, there is a simultaneous production of an amount of heat exactly proportional to the motive power that is destroyed. Conversely, whenever there is destruction of heat, motive power is produced. Hence, we may state, as a general proposition, that the quantity of motive power in nature is fixed, and that, strictly speaking, motive power is neither produced nor destroyed. It is true that it changes its form' that is, it simetimes produces one kind of motion, sometimes another. But it is never annihilated.” [11] |
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| Men of the Carnot family: Lazare Carnot (father), Sadi Carnot (thermodynamicist), and Hippolyte Carnot (brother). |
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| Sadi Carnot at age 34 (1830) [8] | ||
“No heat is lost in the process, but that the quantity of heat remains unchained … this fact is not doubted; it was assumed at first without investigation, and then established in many cases by calorimetric measurements. To deny this would overthrow the whole theory of heat, of which it is the foundation.”
“The celebrated memoir on the motive power of heat, published in 1824 by Sadi Carnot, then only 28 years of age, has become extremely rare. The work passed long without notice, and did not acquire any fame until it was perceived to be the true origin of the magnificent researches of Clausius, Rankine, Joule, and several others in thermo-dynamics. Physicists will be pleased to learn that Hyppolyte Carnot, brother of the author, and Senator, has reedited this work, which has so much historical interest; also that the new edition is enriched with notes hitherto unpublished, and one of which, at least, has considerable importance. It proves, in fact, that Sadi Carnot, by the end of his too short life, had come to regard thermodynamics in their true light, perceiving that the work done by the steam-engine represents a transformation of heat. The manuscript of the memoir and the notes will be deposited in the Library of the French Academy.”— Anon (1879), notice (Ѻ), English Mechanic and World of Science, 717:418, Jan 3
“Nicolas-Leonard-Sadi Carnot was, perhaps, the greatest genius, in the department of physical science at least, that this century has produced.”— Robert Thurston (1890) [7]
“Carnot’s argument is perhaps the most original in physical science.”— Joseph Larmor (1918), “On the Nature of Heat” [10]
“In the annals of science, Carnot’s Motive Power of Fire is almost unique, for it had no discernible predecessors and was built up from the assemblage of unordered opinions and problems, concepts, theories and measurements that were available at the time. Carnot, in short, was not standing on the shoulders of giants; he saw further than his contemporaries because he had a much clearer vision.”— Donald Cardwell (1971), From Watt to Clausius (pg. 193)
“The most original work ever written in the physical sciences, with a core of abstraction comparable to the best of Galileo”— Tom Shachtman (1999), Absolute Zero and the Quest for Absolute Cold [9]
“Say little about what you know and nothing at all about what you don’t know. When a discussion degenerates into a dispute, keep silent. Do not do anything which the whole world cannot know about.”— Sadi Carnot (c.1820), “Rules of Conduct”, personal notes [6]
