Place of Sadi Carnot in the History of Thennotics. 21 



of modern thermodynamic investigation. • Prof. Tait justly 

 asserts* that, without this basis, the dynamical theory of heat 

 could never have obtained, in so brief a period, the wonderful 

 development witnessed during the past half -century. Carnot's 

 imj)erfect enunciation and demonstration of these points, re- 

 mained unfruitful until, a quarter of a century later, Thompson 

 and Rankine commenced their work in this field. The former 

 then called attention to the work of Carnot, f and adapted his 

 conception to the dynamical theory and perfected the typical 

 cycle. 



Carnot's original work contains no evidence that he accepted 

 the dynamical theory of heat, and it has only now become evi- 

 dent that, if not then aware of the falsity of the material 

 hypothesis, he soon became conscious of it, and fully accepted 

 the true theory. 



His value (370) for the dynamical equivalent, is not nearly as 

 close an approximation as that obtained by earlier investigators. 

 Rumford, especially, not only accej)ted, and in 1798 published 

 in the Philosophical Transactions, a complete and definite state- 

 ment of the equivalence of heat and work, but gave data, as 

 shown by the writer, J giving the value 783.8 foot-pounds, or 

 within 1-5 per cent, of the now accepted value. This fact, 

 hoAvever, while creditable to Rumford as the first correct ex- 

 pounder and the exjoerimental discoverer, does not detract from 

 the honor due Carnot as the propounder of his method. 



It is certainly unfortunate that the manuscript notes left by 

 Carnot could not have been published by him ; and still more 

 unfortunate is it that he had not earlier announced his belief 

 and incorporated the dynamical theory of heat in his great work. 

 His already great reputation, as it is, will be hightened by their 

 tardy publication; but had he made the "Reflexions" the 

 vehicle of their presentation, Carnot would indisputably have 

 earned the position, which is now sometimes denied him, of the 

 founder of the modern science of heat-dynamics. 



* Recent Advancea in Physical Science. 



t See Tail's History of Tliermodynamics : — also, Phil. Mag., 1872. 



X Trans. American Society of Civil Engineers, 1873. 



