14 THE WORK OF SADI CAENOT. 



and Dal ton ; and that, therefore, according to the 

 laws of thermodynamics as lie has demonstrated 

 them, the heat absorbed with equal augmenta- 

 tions of volume being the same, the two specific 

 heats are constant, and their difference as well. As 

 will be seen on referring to the text, he bases upon 

 this principle a determination of the specific heats 

 of constant volume, taking as his values of the de- 

 termined specific heats of constant pressure those 

 of Delaroche and Berard, making the constant 

 difference 0.300, that of air at constant pressure 

 being taken as the standard and as unity. The 

 establishment of this point, in the face of the op- 

 position, and apparently of the facts, of the best 

 physicists of his time, was one of those circum- 

 stances which did so much to win for Clausius his 

 great fame. How much greater credit, then, 

 should be given Carnot, who not only anticipated 

 the later physicists in this matter, but who must 

 have enunciated his principle under far more seri- 

 ous discouragements and uncertainty ! 



It must be remembered, when reading Oar- 

 not, that ,all the "constants of nature" were, in 

 his time, very inaccurately ascertained. It is only 

 since the time of Regnault's grand work that it has 

 been the rule that such determinations have been 

 published only when very exactly determined. No 



