290 CLASSICS OF MODERN SCIENCE 

 now we perhaps see similar masses in the distant regions of the 

 firmament, as patches of nebulae, and nebulous stars ; within our 

 system also, comets, the zodiacal light, the corona of the sun during 

 a total eclipse, exhibit remnants of a nebulous substance, which is 

 so thin that the light of the stars passes through it unenfeebled and 

 unrefracted. If we calculate the density of the mass of our planetary 

 system, according to the above assumption, for the time when it 

 was a nebulous sphere, which reached to the path of the outmost 

 planet, we should find that it would require several cubic miles of 

 such matter to weigh a single grain. 



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

 these masses to each other, and to condense, so that the nebu- 

 lous sphere became incessantly smaller, by which, according to mechan- 

 ical laws, a motion of 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 

 neighbourhood of the equator of the nebulous sphere, masses could 

 from time to time be torn away, which afterwards 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 im- 

 mense 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 to- 

 wards 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 



