UNIVERSITY 



THE WORK OF 8ADI CARNOT. 



was eight. Carnot had done his grandest work of 

 the century in his province of thought, and had 

 passed into the Unseen, at thirty-six ; his one little 

 volume, which has made him immortal, was writ- 

 ten when he was but twenty-three or twenty-four. 

 It is unnecessary, here, to enter into the particu- 

 lars of his life ; that has been given us in ample 

 detail in the admirable sketch by his brother 

 which is here republished. It will be quite suf- 

 ficient to indicate, in a few words, what were the 

 conditions amid which he lived and the relation 

 of his work to that great science of which it was 

 the first exposition. 



At the time of Carnot, the opinion of the 

 scientific world was divided, as it had been for 

 centuries, on the question of the true nature of 

 heat and light, and as it still is, to a certain ex- 

 tent, regarding electricity. On the one hand it 

 was held by the best-known physicists that heat 

 is a substance which pervades all bodies in greater 

 or less amount, and that heating and cooling are 

 simply the absorption and the rejection of this 

 " imponderable substance " by the body affected ; 

 while, on the other hand, it was asserted by a 

 small but increasing number that heat is a 

 "mode of motion," a form of energy, not only 

 imponderable, but actually immaterial ; a quality 



