316 ON THE CONSERVATION OF FORCE. 



for processes in organic nature, so far as the facts have been 

 tested. 



It follows thence that the total quantity of all the forces ca- 

 pable of work in the whole, universe remains eternal and un- 

 changed throughout all their changes. All change in nature 

 amounts to this, that force can change its form and locality 

 without its quantity being changed. The universe possesses, 

 once for all, a store of force which is not altered by any change 

 of phenomena, can neither be increased nor diminished, and 

 which maintains any change which takes place on it. 



You see how, starting from considerations based on the 

 immediate practical interests of technical work, we have been 

 led up to a universal natural law, which, as far as all previous 

 experience extends, rules and embraces all natural processes; 

 which is no longer restricted to the practical objects of human 

 utility, but expresses a perfectly general and particularly cha- 

 racteristic property of all natural forces, and which, as regards 

 generality, is to be placed by the side of the laws of the unalter- 

 ability of mass, and the unalterability of the chemical elements. 



At the same time, it also decides a great practical question 

 which has been much discussed in the last two centuries, to the 

 decision of which an infinity of experiments has been made 

 and an infinity of apparatus constructed that is, the question 

 of the possibility of a perpetual motion. By this was under- 

 stood a machine which was to work continuously without the 

 aid of any external driving force. The solution of this problem 

 promised enormous gains. Such a machine would have had all 

 the advantages of steam without requiring the expenditure of 

 fuel. Work is wealth. A machine which could produce work 

 from nothing was as good as one which made gold. This 

 problem had thus for a long time occupied the place of gold 

 making, and had confused many a pondering brain. That a 

 perpetual motion could not be produced by the aid of the then 

 known mechanical forces could be demonstrated in the last 

 century by the aid of the mathematical mechanics which had at 

 that time been developed. But to show also that it is not 

 possible even if heat, chemical forces, electricity, and magnetism 



