176 POPULAR SCIENCE MONTHLY. 



See regards as theoretically possible, but apparently he thinks that if 

 it took place it was confined to our system. 



The other method is that of the separation of the original rotating 

 mass into two nearly equal parts. The mechanical possibility of 

 such a process has been proved, mathematically, by Poincare and 

 Darwin. This, Dr. See thinks, is the method which has prevailed 

 among the stars, and prevailed to such a degree as to make the solar 

 system, formed by the ring method, probably a unique phenomenon 

 in the universe. 



Is it not more probable that both methods have been in opera- 

 tion, and that, in fact, the ring method has operated more frequently 

 than the other? If not, why do the single stars so enormously out- 

 number the double ones? It is of the essence of the fission process 

 that the resulting masses should be comparable in size. If, then, 

 that process has prevailed in the stellar universe to the practical 

 exclusion of the other, there should be very few single stars; where- 

 as, as a matter of fact, the immense majority of the stars are single. 

 And, remembering that the sun viewed from stellar distances would 

 appear unattended by subsidiary bodies, are we not justified in con- 

 cluding that its origin is a type of the origin of the other single 

 stars? 



While it is, as I have remarked, of the essence of the fission 

 process that the resulting parts of the divided mass should be com- 

 parable in magnitude, it is equally of the essence of the ring, or 

 Laplace, process that the bodies separated from the original mass 

 should be comparatively insignificant in magnitude. 



As to the coexistence of the two processes, we have, perhaps, an 

 example in the solar system itself. Darwin's demonstration of the 

 possible birth of the moon from the earth, through fission and tidal 

 friction, does not apply to the satellites attending the other planets. 

 The moon is relatively a large body, comparable in that respect with 

 the earth, while the satellites of Jupiter and Saturn, for instance, 

 are relatively small. But in the case of Saturn there is visible evi- 

 dence that the ring process of satellite formation has prevailed. 

 The existing rings have not broken up, but their very existence is a 

 testimony of the origin of the satellites exterior to them from other 

 rings which did break up. Thus we need not go as far away as the 

 stars in order to find instances illustrating both the methods of nebu- 

 lar evolution that we have been dealing with. 



The conclusion, then, would seem to be that we should not be 

 justified in assuming that the solar system is unique simply because 

 it differs widely from the double and multiple star systems; and 

 that we should rather regard it as probable that the vast multitude 

 of stars which do not appear, when viewed with the telescope, or 



