NATURAL PHILOSOPHY. 131 



The general attractive force of all matter must, however, impel these 

 masses to approach each other, and to condense, so that the nebulous sphere 

 bwnme incessantly smaller, by Avhich, according to mechanical laws, a mo- 

 tion ur' rotation originally slow, and the existence of which must be assumed, 

 would gradually become quicker and quicker. By the centrifugal force 

 which must act most energetically in the neighborhood of the equator of the 

 nebulous sphere, masses could from time to time be torn away, which after- 

 wards would continue their courses separate from the main mass, forming 

 themselves into single planets, or, similar to the great original 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 system, 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 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 down- 

 wards 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, condensation 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 rim 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 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. 



Let us make this addition to our assumption ; that, at the commencement, 

 the density of the nebulous matter was a vanishing quantity, as compared 

 with the present density of the sun and planets ; we can then calculate how 

 much work has been performed by the condensation ; we can further calcu- 

 late how much of this work still exists in the form of mechanical force, as 

 attraction of the planets towards the sun, and as vis viva of their motion, 

 and find, by this, how much of the force has been converted into heat. 



The result of tliis calculation is, that only about the 454th part of the 



