172 ON THE INTERACTION OF NATURAL FORCES. 



and must continue to be such ; the other, to which a por- 

 tion of the heat of the warmer bodies, and the total sup- 

 ply of chemical, mechanical, electrical, and magnetical 

 foraes belong, is capable of the most varied changes of 

 f<>Tm, and constitutes the whole wealth of change which 

 takes place in Nature. 



But the heat of the warmer bodies strives perpetually 

 to pass to bodies less warm by radiation and conduction, 

 and thus to establish an equilibrium of temperature. At 

 each motion of a terrestrial body a portion of mechanical 

 force passes by friction or collision into heat, of which 

 only a part can be converted back again into mechanical 

 force. This is also generally the case in every electrical 

 and chemical process. From this it follows that the first 

 portion of the store of force, the unchangeable heat, is 

 augmented by every natural process, while the second 

 portion, mechanical, electrical, and chemical force, must 

 be diminished ; so that if the universe be delivered over 

 to the undisturbed action of its physical processes, all 

 force will finally pass into the form of heat, and all heat 

 come into a state of equilibrium. Then all possibility of 

 a further change would be at an end, and the complete 

 cessation of all natural processes must set in. The life of 

 men, animals, and plants could not of course continue if 

 the sun had lost his high temperature, and with it his 

 light, if all the components of the earth's surface had 

 closed those combinations which their affinities demand. 

 In short, the universe from that time forward would be 

 condemned to a state of eternal rest. 



These consequences of the law of Carnot are, of course, 

 only valid provided that the law, when sufficiently tested, 

 proves to be universally correct. In the mean time there 

 is little prospect of the law being proved incorrect. At 

 all events, we must admire the sagacity of Thomson, who, 

 in the letters of a long-known little mathematical for- 



