PLANETARY EVOLUTION 



the bulging equatorial zone, no longer able to 

 keep pace with the rest of the mass in its con- 

 traction, was left behind as a detached ring, gir- 

 dling, at a small but steadily increasing distance, 

 the retreating central mass. 



What must now have been the career of this 

 detached ring? Unless subjected to absolutely- 

 symmetrical forces in all directions — an infi- 

 nitely improbable supposition — such a ring 

 must forthwith break into a host of fragments 

 of very unequal dimensions. For in order that 

 it should break into equal-sized fragments, the 

 strains exerted upon it must be disposed with 

 absolute symmetry; and against this supposi- 

 tion also the probabilities are as infinity to one. 

 It would break, much as a dish breaks when 

 dropped on the floor, into hundreds of frag- 

 ments, of which some few would be relatively 

 large, while the numerous small ones would vary 

 endlessly in their sizes. At this stage, then, in- 

 stead of a continuous ring, we have a host of 

 satellites, surrounding the solar equator, revolv- 

 ing in the direction of the solar rotation, and 

 following each other in the same orbit. If un- 

 disturbed by any powerful attraction from with- 

 out, these fragments would continue in the same 

 orbit, and would gradually differ more and more 

 in their velocities. Each large fragment would, 

 by its gravitative force, retard the smaller frag- 

 ment in front of it, and accelerate the smaller 



VOL. II. ^57 



