Reflections on the Motive Power of Fire
Reflections on the Motive Power of Fire and on Machines Fitted to Develop that Power is a book published in 1824 by French physicist Sadi Carnot. The 65-page book's French title was Réflexions sur la puissance motrice du feu et sur les machines propres à développer cette puissance. It is a significant publication in the history of thermodynamics about a generalized theory of heat engines.
The book is considered the founding work of thermodynamics. It contains the preliminary outline of the second law of thermodynamics. Carnot stated that motive power is due to the fall of caloric (heat) from a hot to a cold body.
The work was unnoticed until 1834 when French mining engineer Émile Clapeyron put it on a graphical footing in his Memoir on the Motive Power of Heat. Through Clapeyron's paper, German physicist Rudolf Clausius learned of Carnot's theory of heat and through a modification of Carnot's suppositions on heat, Clausius put the second law in mathematical form with his introduction of the concept of entropy.
The Reflections contain a number of principles such as the Carnot cycle, the Carnot heat engine, Carnot's theorem, thermodynamic efficiency. Similar to how the Reflections was the precursor to the second law, English physicist James Joule's 1843 paper Mechanical equivalent of heat was the precursor to the first law of thermodynamics.
Despite the fact that the caloric theory of heat was incorrect, Carnot's work brought together three insights that remain relevant and was used by his successors that lead to the concept of entropy:
- The "fall of heat" from a high temperature to a lower temperature is where the work comes from.
- Analyzing a cycle, rather than an open system, is the correct way to analyze a heat engine.
- The concept of a reversible process.
- Carnot (1890), Thurston's introduction.
- Dover edition.
- Clausius, R. (1867). The Mechanical Theory of Heat – with its Applications to the Steam Engine and to Physical Properties of Bodies. London: John van Voorst, 1 Paternoster Row. MDCCCLXVII.
- Kelvin, William T. (1849) "An Account of Carnot's Theory of the Motive Power of Heat - with Numerical Results Deduced from Regnault's Experiments on Steam." Transactions of the Edinburg Royal Society, XVI. January 2. Scanned Copy
- Carnot, Sadi (1824). Réflexions sur la puissance motrice du feu et sur les machines propres à développer cette puissance. Paris: Bachelier. (French) (full text)
- Carnot, Sadi; Thurston, Robert Henry (editor and translator) (1890). Reflections on the Motive Power of Heat and on Machines Fitted to Develop That Power. New York: J. Wiley & Sons. (full text of 1897 ed.)) (html)
- Carnot, Sadi; E. Clapeyron; R. Clausius (2005). Reflections on the Motive Power of Fire – and other Papers on the Second Law of Thermodynamics. Edited with an introduction by E. Mendoza. New York: Dover Publications. ISBN 0-486-44641-7.