74 Sohir and Planetarij Evolution. 



lirst cause the balling together of some small liquid or solid 

 masses like meteorites ; a series of these meteorites would com- 

 mence to revolve in rings, and, attracting one another, would di- 

 minish in number and increase in size. The largest of these 

 bodies, in a given region, growing larger by accessions from all 

 directions, would become more and more heated, by the triple 

 cause of converging motion and impact, pressure on their centers, 

 and chemical action by the contact of the diiferent elements con- 

 stituting them. These would constitute the suns, around which 

 the smaller bodies would revolve. 



The resiilt of atoms and meteorites thus converging would be 

 to produce in each a spiral motion toward the center, increasing 

 both the angular and the direct velocity of each, until the force 

 thus generated became powerful enough to balance gravitation, 

 when rings would form, ultimately breaking up into planets. 

 The outside of each fluid ring, in this case, w^ould move more rap- 

 idly than its inside, and the resultant globes would therefore ro- 

 tate in the same direction as the central mass. This is the case- 

 in our solar system, with all the planets inside the orbit of Ura- 

 nus. The contrary motion of the tAvo outer planets renders it prob- 

 able that there was a projecting part of the primitive nebula, be- 

 tween which and the main mass the chief cvirrent of rotation found 

 its way. Thus, the simple law of gravitation, acting upon neb- 

 ulous matter unequally diffused thi-ough space, is sufficient to ex- 

 plain all the results observed in this admirable system of worlds. 



The Pkesident, Dk. Lewis G. .Taxes: — 



There is evidently a wide field in this discussion for the exercise 

 of the scientiflc imagination. The point to be noted is, that al- 

 though astronomers are not agreed as to the jirecise method by 

 which the suns and Avorlds have been brought into being, there is 

 a very general agreement that it has been effected by natural 

 causes — by some process of evolution. 



I desire to call your attention, as relating to a subsequent branch 

 of this discussion, to the fact that there are two classes of i)hi- 

 losophical thinkers who can logically take no interest in this even- 

 ing's discussion. First, the Positivists, who can see no direct bear- 

 ing of astronomical studies upon human welfare, and therefore 

 deem them unworthy of our serious attention, classing them with 

 those metaphysical and ontological studies which they affect to 

 condemn. Secondly, the consistent Idealist, to whom all this vast 

 realm of the heavenly spaces — the universe itself — is but a fig- 



