360 LAPLACE. 



indefinite stability of the rings would have required a 

 regularity of structure throughout their whole contour, 

 which is very improbable. Each of them accordingly 

 broke in its turn into several masses, which were plainly 

 endued with a movement of rotation, coinciding in direc- 

 tion with the common movement of revolution, and 

 which in consequence of their fluidity assumed spheroi- 

 dal forms. 



In order, then, that one of those spheroids might ab- 

 sorb all the others belonging to the same ring, it will be 

 sufficient to assign to it a mass greater than that of any 

 other spheroid. 



Each of the planets, while in the vaporous condition to 

 which we have just alluded, would manifestly have a cen- 

 tral nucleus gradually increasing in magnitude and mass, 

 and an atmosphere offering, at its successive limits, phe- 

 nomena entirely similar to those which the solar atmos- 

 phere, properly so called, had exhibited. We here 

 witness the birth of satellites, and that of the ring of 

 Saturn. 



The system, of which I have just given nn imperfect 

 sketch, has for its object to show how a nebula endued 

 with a general movement of rotation must eventually 

 transform itself into a very luminous central nucleus 

 (a sun) and into a series of distinct spheroidal planets, 

 situate at considerable distances from each other, revolv- 

 ing all around the central sun in the direction of the orig- 

 inal movement of the nebula ; how these planets ought 

 also to have movements of rotation operating in similar 

 directions ; how, finally, the satellites, when any of such 

 are formed, cannot fail to revolve upon their axes and 

 around their respective primaries, in the direction of rota- 

 tion of the planets and of their movement of revolution 

 around the sun. 



