8 FRAGMENTS OF SCIENCE 



them went mad in the pursuit of this object. The faith 

 in such a consummation, involving, as it did, immense 

 personal profit to the inventor, was extremely exciting, 

 and every attempt to destroy this faith was met by bitter 

 resentment on the part of those who held it. Gradually, 

 however, as men became more and more acquainted with 

 the true functions of machinery, the dream dissolved. 

 The hope of getting work out of mere mechanical com- 

 binations disappeared: but still there remained for the 

 speculator a cloud-land denser than that which filled the 

 imagination of the Tyrolese priest, and out of which he 

 still hoped to evolve perpetual motion.. There was the 

 mystic store of chemic force, which nobody understood; 

 there were heat and light, electricity and magnetism, all 

 competent to produce mechanical motion. 1 Here, then, 

 was the mine in which our gem must be sought. A mod- 

 ified and more refined form of the ancient faith revived; 

 and, for aught I know, a remnant of sanguine designers 

 may at the present moment be engaged on the problem 

 which like-minded men in former ages left unsolved. 



And why should a perpetual motion, even under mod- 

 ern conditions, be impossible? The answer to this ques- 

 tion is the statement of that great generalization of modern 

 science, which is known under the name of the Conserva- 

 tion of Energy. This principle asserts that no power can 

 make its appearance in nature without an equivalent ex- 

 penditure of some other power; that natural agents are 

 so related to each other as to be mutually convertible, 

 but that no new agency is created. Light runs into heat; 

 heat into electricity; electricity into magnetism; magne- 



1 See Helmholtz: "Wechselwirkung der Naturkraf te. " 



