458 POPULAR LECTURES AND ADDRESSES, 



with his first determination of the Mechanical 

 Equivalent of Heat. 



To the reprint (sixty-five pages) of Carnot's 

 original essay of 1824 are appended thirty-three 

 pages of Extrait de Notes Inedites de Sadi Carnot, 

 sur les Mathtmatiques, la Physique, et autres sujets, 

 and twenty-one pages of biographical sketch of 

 the author, by his younger brother, Hippolytc 

 Carnot, whose name, as a very benevolent writer 

 and worker in political and social affairs, was well 

 known in 1845! among Paris booksellers, none of 

 whom, so far as my inquiries went, had ever heard 

 of Sadi or his Reflexions sur la Piiissance Motrice 

 du Feu. 



Here are some of Carnot's words literally 

 translated (from pp. 95, 96): 



" Heat is nothing else than motive power, or 

 " rather motion which has changed its form. It 



1 I went to every book-shop I could think of, asking for the 

 J'ni usance Riot rice du Fcit, by Carnot. " Caino ? Je ne connais pas 

 cet auteur." With much difficulty I managed to explain that it 

 was "r" not "i" I meant. "Ah! Ca-rrr-not ! Oui, voici son 

 ouvrage," producing a volume on some social question by Ilippolyte 

 Carnot ; but the Puissance Motrice du Fen was quite unknown. 



