176 ox THE IXTERACTION OF NATURAL FORCES. 



When the nebulous chaos first separated itself from 

 other fixed star masses it must not only have contained 

 all kinds of matter which was to constitute the future 

 planetary system, but also, in accordance with our new 

 law, the whole store of force which at a future time ought 

 to unfold therein its wealth of actions. Indeed, in this 

 respect an immense dower was bestowed in the shape of 

 the general attraction of all the particles for each other. 

 This force, which on the earth exerts itself as gravity, 

 acts in the heavenly spaces as gravitation. As terrestrial 

 gravity when it draws a weight downwards performs work 

 and generates vis viva, so also the heavenly bodies do the 

 same when they draw two portions of matter from distant 

 regions of space towards each other. 



The chemical forces must have been also present, ready 

 to act ; but as these forces can only come into operation 

 by the most intimate contact of the different masses, con- 

 densation must have taken place before the play of chemical 

 forces began. 



Whether a still further supply of force in the shape of 

 heat was present at the commencement we do not know. 

 At all events, by aid of the law of the equivalence of heat 

 and work, we find in the mechanical forces existing at the 

 time to which we refer such a rich source of heat and light, 

 that there is no necessity whatever to take refuge in the 

 idea of a store of these forces originally existing. When, 

 through condensation of the masses, their particles came 

 into collision and clung to each other, the vis vivaoi their 

 motion would be thereby annihilated, and must reappear 

 as heat. Already in old theories it has been calculated 

 that cosmical masses must generate heat by their col- 

 lision, but it was far from anybody's thought to make 

 even a guess at the amount of heat to be generated in 

 this way. At present we can give definite numerical 

 values with certainty. 



