EXPLANATION OF SATURN 's RINGS. 271 



signed for their existence in the place where we find them. 

 But on the hypothesis of evohition, the arrangement, so far 

 from offering a difficulty, offers another confirmation. 

 These rings are found where alone they could have been 

 produced — close to the body of a planet whose centrifu- 

 gal force bears a great proportion to his gravitative force. 

 That permanent rings should exist at any great distance 

 from a planet's body, is, on the Nebular Hypothesis, mani- 

 festly impossible. Rings detached early in the process of 

 concentration, and tlierefore consisting of gaseous matter 

 having extremely little power of cohesion, can have no 

 ability to resist the disrupting forces due to imperfect bal- 

 ance ; and must, therefore, collapse into satellites. A liquid 

 ring is the only one admitting of permanence. But a liquid 

 ring can be produced only when the aggregation is ap- 

 proaching its extreme — only when gaseous matter is j^ass- 

 ing into liquid, and the mass is about to assume the plane- 

 tary form. And even then it cannot be produced save un- 

 der special conditions. Gaining a rapidly-increasing pre- 

 ponderance, as the gravitative force does during the closing 

 stages of concentration, the centrifugal force cannot in or- 

 dinary cases cause the detachment of rings when the mass 

 has become dense. Only where the centrifugal force has 

 all along been very great, and remains powerful to the last, 

 as in Saturn, can Hquid rings be formed. Thus the Nebu- 

 lar Hypothesis shows us why such" ai^pendages surround 

 Saturn, but exist nowhere else. 



And then, let us not forget the fact, discovered within 

 these few years, that Saturn possesses a nebulous ring, 

 through which his body is seen as through a thick veil. In 

 a position where alone such a thing seems preservable — 

 suspended, as it were, between the denser rings and the 

 planet — there still continues one of these annular masses of 

 diffused matter from which satellites and planets are be- 

 lieved to have originated. 



