232 INTERACTION OF NATURAL FORCES. 



themselves into single planets, or, similar to the great origi- 

 nal sphere, into planets with satellites and rings, until finally 

 the principal mass condensed itself into the sun. With 

 regard to the origin of heat and light, this view gives us no 

 information. 



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 sys- 

 tem, but also, in accordance with our new law, the whole 

 store of force which at one time must 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 par- 

 ticles 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 con- 

 densation of the masses their particles came into collision, 

 and clung to each other, the vis viva of 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 collision, but it was far from any body's 



