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 diree- 
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. 
Kach 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 an 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. 
