2 VESTIGES OF THE 



attended with the eifect of separating the mass and its 

 outer parts. These outer parts would, then, be left as 

 a ring round the central body, which ring would con- 

 tnuie to revolve with the velocity possessed by the cen- 

 tral mass at the moment of separation, but not neces- 

 sarily participating in a-ny changes afterwards undergone 

 by that body. This is a process which might be repeated 

 as soon as a new excess arose in the centrifugal over the 

 attractive forces working in the parent mass. It might, 

 indeed, continue to be repeated, until the mass attained 

 the ultimate limits of the condensation which its con- 

 stitution imposed upon it. From what cause might arise 

 the periodical occurrence of an excess of the centrifugal 

 force ? If we suppose the agglomeration of a nebulous 

 mass to be a process attended by refrigeration or cooling, 

 which many facts render likely, we can easily under- 

 stand why the outer parts, hardening under this process, 

 might, by virtue of the greater solidity thence acquired, 

 begin to present some resistance to the attractive force. 

 As the solidihcation proceeded, this resistance would 

 become greater, though there would still be a tendency 

 to adhere. Meanwhile, the condensation of the central 

 mass would be going on, tending to produce a separation 

 from what may now be termed the solidifijuKj crust. 

 During the contention between the attractions of these 

 two bodies, or parts of one body, there would probably 

 be a ring of attenuation between the mass and its crust. 

 At length, when the central mass had reached a certain 

 stage in its advance towards solidification, a separation 

 would take place, and the crust would become a detached 

 I'ing. It is clear, of course, that some law presiding 

 over the refrigeration of heated gaseous bodies would 

 determine the stages at which rings were thus formed 

 and detached. We do not know any such la\\-. but what 



