IV.* 



CARNOT'S THEORY OF THE MOTIVE POWER 

 OF HEAT, f 



WITH NUMERICAL RESULTS DEDUCED FROM REGNAULT'S 

 EXPERIMENTS ON STEAM. J 



BY SIR WILLIAM THOMSON [LORD KELVIN], 



1. THE presence of heat may be recognized in 

 every natural object ; and there is scarcely an 

 operation in nature which is not more or less 



* From Transactions of the Edinburgh Royal Society, xiv. 

 1849 ; Annales de Chimie, xxxv. 1852. 



f Published in 1824, in a work entitled "Reflexions BUT 

 la Puissance Motrice du Feu, et sur les Machines Propres d 

 Developer cette Puissance. Par S. Car not." [Note of Nov. 

 5, 1881. The original work has now been republished, 

 with a biographical notice, Paris, 1878.] 



\ An account of the first part of a series of researches 

 undertaken by Mons. Regnault, by order of the late 

 French Government, for ascertaining the various physical 

 data of importance in the theory of the steam-engine, has 



