On the Formation of the Universe. 141 



direction of P's motion, which would be continued toward 

 the stationary point at s, because toward that point the force 

 would be instantly and constantly increased, while toward 

 that at m it would be in like manner diminished. But if the 

 part of the ring at s were considerably more massive than 

 the other parts, then as s passed round, P would incline to 

 follow it : but s constantly changing the direction of its force 

 on P, would tend to draw it from its original direction; while 

 the momentum, acquired by P, would tend to continue it in that 

 direction; and P would eventually move in a small orbit within 

 the ring. For sometime after the commencement of P's mo- 

 tion, s would act upon it in some chord of P's orbit. The direci- 

 tion of its action would continually move toward the centre of 

 motion, till it arrived at it, and there it would stop ; and the 

 centre of motion would coincide with the centre of gravity. 

 For P having acquired its greatest possible motion, and that 

 of s being reduced to its least degree, s would have no ten- 

 dency to vibrate to the other side, and of course could not 

 draw P backward in its orbit. The same reasoning will ap- 

 ply to the sun and planets, and to the primary planets and 

 their satellites, and the general centres of motion and of 

 gravity, in every case that has been assumed in explaining 

 the formation of the system, would in like manner be adjust- 

 ed. The account which Dr. Robison has given of the 

 formation of Saturn's ring, is incomparably more natural 

 than the explosive theory of the asteroid. Notwithstand- 

 ing, there appears to be considerable difficulty attending it. 

 The form which glass assumes, by whirling when in a viscid 

 state, gives it a very considerable degree of plausibility ; but 

 the mutual attraction between the parts of a small glass 

 plate must be very trifling compared with that in the ring of 

 Saturn, so that the analogy is very incomplete. The dis- 

 tance between the limits of the smaller and greater spheroids, 

 which may be produced in the same body of fluid or aerial 

 matter, by the same angular velocity, is very great ; and the 

 body while passing between these limits could not maintain 

 an equilibrium. Its parts must of course while passing 

 through the whole of that distance tend to collect together 

 irregularly. Besides, a whirling plate of glass is thicker at 

 the circumference, than at the parts between the centre and 

 circumference ; so that the analogy, imperfect as it is, mili- 

 tates against the theory. But if the case were attended with 

 no difficulty, Dr. Robison has, at least in some degree, gone 



