ON THE ORIGIN OF THE PLANETAEY SYSTEM. 173 



ones which we meet with in all the bodies we have 

 named. There is, in fact, a complete irregularity in 

 the comets and meteoric swarms, which we have 

 much reason for considering to be formations which 

 have only accidentally come within the sphere of the 

 sun's attraction. 



The number of coincidences in the orbits of the 

 planets and their satellites is too great to be ascribed 

 to accident. We must inquire for the reason of this 

 coincidence, and this can only be sought in a primi- 

 tive connection of the entire mass. Now, we are 

 acquainted with forces and processes which condense 

 an originally diffused mass, but none which could drive 

 into space such large masses, as the planets, in the 

 condition we now find them. Moreover, if they had 

 become detached from the common mass, at a place 

 much nearer the sun, they ought to have a markedly 

 elliptical orbit. We must assume, accordingly, that 

 this mass in its primitive condition extended at least 

 to the orbit of the outermost planets. 



These were the essential features of the considera- 

 tions which led Kant and Laplace to their hypothesis. 

 In their view our system was originally a chaotic ball 

 of nebulous matter, of which originally, when it ex- 

 tended to the .path of the most distant planet, many 

 billions of cubic miles could contain scarcely a gramme 

 of mass. This ball, when it had become detached from 



