288 CLASSICS OF MODERN SCIENCE 

 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 dehvered 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 its high temperature, and with it his light, — if all the com- 

 ponents of the earth's surface had closed those combinations which 

 their afBnities demand. In short, the universe from that time for- 

 ward 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 sufificiently 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 

 formula, which only speaks of the heat, volume, and pressure of 

 bodies, was able to discern consequences which threatened the universe, 

 though certainly after an infinite period of time, with eternal death. 



I have already given you notice that our path lay through a thorny 

 and unrefreshing field of mathematico-mechanical developments. We 

 have now left this portion of our road behind us. The general prin- 

 ciple which I have sought to lay before you has conducted us to a 

 point from which our view is a wide one, and aided by this principle, 

 we can now at pleasure regard this or the other side of the surround- 

 ing world, according as our interest in the matter leads us. A glance 

 into the narrow laboratory of the physicist, with its small appliances 

 and complicated abstractions, will not be so attractive as a glance 

 at the wide heaven above us, the clouds, the rivers, the woods, and 

 the living beings around us. While regarding the laws which have 

 been deduced from the physical processes of terrestrial bodies, as 

 applicable also to the heavenly bodies, let me remind you that the 

 same force which, acting at the earth's surface, we call gravity 

 (Schwere) , acts as gravitation in the celestial spaces, and also mani- 

 fests its power in the motion of the immeasurably distant double 



