''Reflections on the Motive Power of Fire and on Machines Fitted to Develop that Power'' is a book published in 1824 by French

physicist A physicist is a scientist who specializes in the field of physics, which encompasses the interactions of matter and energy at all length and time scales in the physical universe. Physicists generally are interested in the root or ultimate cau ...

Sadi Carnot.
full text of 1897 ed.
( Full text of 1897 edition on Wikisource ) The 118-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 The history of thermodynamics is a fundamental strand in the history of physics, the history of chemistry, and the history of science in general. Owing to the relevance of thermodynamics in much of science and technology, its history is finely w ...

about a generalized theory of

heat engine In thermodynamics and engineering, a heat engine is a system that converts heat to mechanical energy, which can then be used to do mechanical work. It does this by bringing a working substance from a higher state temperature to a lower state ...

Overview

The book is considered the founding work of

thermodynamics Thermodynamics is a branch of physics that deals with heat, work, and temperature, and their relation to energy, entropy, and the physical properties of matter and radiation. The behavior of these quantities is governed by the four laws of th ...

. It contains the preliminary outline of the

second law of thermodynamics The second law of thermodynamics is a physical law based on universal experience concerning heat and energy interconversions. One simple statement of the law is that heat always moves from hotter objects to colder objects (or "downhill"), unles ...

. Carnot stated that

motive power ''Motive Power'' is a bi-monthly railway related magazine that focuses on diesel locomotives in Australia. The first issue was published on 23 August 1998. Its headquarters is in Sydney. The content includes photographs of locomotives & trains, ...

is due to the fall of caloric (

heat In thermodynamics, heat is defined as the form of energy crossing the boundary of a thermodynamic system by virtue of a temperature difference across the boundary. A thermodynamic system does not ''contain'' heat. Nevertheless, the term is ...

) 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 Rudolf Julius Emanuel Clausius (; 2 January 1822 – 24 August 1888) was a German physicist and mathematician and is considered one of the central founding fathers of the science of thermodynamics. By his restatement of Sadi Carnot's principle ...

learned of Carnot's

theory of heat The history of thermodynamics is a fundamental strand in the history of physics, the history of chemistry, and the history of science in general. Owing to the relevance of thermodynamics in much of science and technology, its history is finely w ...

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 Entropy is a scientific concept, as well as a measurable physical property, that is most commonly associated with a state of disorder, randomness, or uncertainty. The term and the concept are used in diverse fields, from classical thermodynam ...

. By 1849, ''thermo-dynamic'', as a functional term, was used in William Thomson's paper ''An Account of Carnot's Theory of the Motive Power of Heat.'' 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 Edinburgh Royal Society, XVI. January 2.'
Scanned Copy
/ref> The ''Reflections'' contain a number of principles such as the

Carnot cycle A Carnot cycle is an ideal thermodynamic cycle proposed by French physicist Sadi Carnot in 1824 and expanded upon by others in the 1830s and 1840s. By Carnot's theorem, it provides an upper limit on the efficiency of any classical thermodynam ...

, the

Carnot heat engine A Carnot heat engine is a heat engine that operates on the Carnot cycle. The basic model for this engine was developed by Nicolas Léonard Sadi Carnot in 1824. The Carnot engine model was graphically expanded by Benoît Paul Émile Clapeyron in 1 ...

, Carnot's theorem,

thermodynamic efficiency In thermodynamics, the thermal efficiency (\eta_) is a dimensionless performance measure of a device that uses thermal energy, such as an internal combustion engine, steam turbine, steam engine, boiler, furnace, refrigerator, ACs etc. For a ...

. Similar to how the ''Reflections'' was the precursor to the second law, English physicist

James Joule James Prescott Joule (; 24 December 1818 11 October 1889) was an English physicist, mathematician and brewer, born in Salford, Lancashire. Joule studied the nature of heat, and discovered its relationship to mechanical work (see energy). T ...

's 1843 paper '' Mechanical equivalent of heat'' was the precursor to the

first law of thermodynamics The first law of thermodynamics is a formulation of the law of conservation of energy, adapted for thermodynamic processes. It distinguishes in principle two forms of energy transfer, heat and thermodynamic work for a system of a constant amou ...

. Despite the fact that the caloric theory of heat was incorrect, Carnot's work brought together three insights that remain relevant and were used by his successors to develop 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.

References

External links

* ''Reflections on the Motive Power of Fire'' (1824), analysed on
BibNum
' (click "À télécharger" for English analysis) * American Institute of Physics, 2011. {{ISBN, 978-0-7354-0985-9. Abstract at

Full article (24 page

, also a

__notoc__ Thermodynamics literature Physics books

Overview

See also

References

External links