ON THE 



ORIGIN AND TRANSFORMATION 

 OF MOTIVE POWER. 



[Being Friday Evening Lecture before the Royal Institution, 

 February 29, 1856 ; from Proc. R. I. repubJished in ] 7 'ol, 

 II. of Mathematical and Physical Papers.'] 



THE speaker commenced by referring to the 

 term work done, as applied to the action of a force 

 pressing against a body which yields, and, to the 

 term mechanical effect produced, which may be 

 either applied to a resisting force overcome, or to 

 matter set in motion. Often the mechanical effect 

 of work done consists in a combination of those 

 two classes of effects. It was pointed out that a 

 careful study of nature leads to no firmer convic- 

 tion than that work cannot be done without pro- 

 ducing an indestructible equivalent of mechanical 

 effect. Various familiar instances of an apparent 



