212 FROM NEBULA TO NEBULA 



At this juncture it is possible that Professor Bicker- 

 ton or his supporters may seek to fall back upon the aid 

 of gravitational attraction to bring the stars into touch. 

 To this position I offer three objections, namely; (1) It 

 is contrary to the traditions of the science, traditions to 

 which Mr. Bickerton, along with Newtonians in general, 

 presumably acknowledges fealty, to the effect that unless 

 the approaching star is by its proper motion headed 

 straight at the sun, it cannot strike the latter, but instead 

 must whirl round it in a conic-section orbit. (2) For the 

 star to come fortuitously within even Neptune 's distance 

 of the sun, the chances would still be found only one in 

 many quadrillions ; altogether too remote a possibility to 

 support Mr. Bickerton 's claim to this theory being a 

 " general order or plan of Nature." Lastly, if, in very 

 truth, the star and sun should collide, not because of their 

 inherent motions, but on account of their mutual attrac- 

 tion, the energy of their resulting critical velocities, di- 

 rected, by Newton's second law, toward their respective 

 centers, would bear to the energy of their proper-motion 

 velocities (based on the known value of the sun's) a ratio 

 of something like 500 2 to 12 2 , or 1,600 to 1, thus ensuring 

 total and not partial impact, thereby completely invali- 

 dating Professor Bickerton 's hypothesis in its very es- 

 sence. 



THE PLANETESIMAL HYPOTHESIS 



There are two hinges to the cosmological shutter- 

 astronomy and geology. In order to make it swing easily 

 both ways, it is not only necessary that the facts of as- 

 tronomy be successfully correlated with one another, and 

 the facts of geology with one another, but both of these 

 sets of facts must likewise be mutually coordinated. 

 Nearly a score of years ago Doctor Thomas Chrowder 

 Chamberlin, who for the past quarter-century has been 

 dean of the scientific faculty of the University of Chicago, 

 undertook to construct a system of cosmology from a 

 geologist's point of view. His researches along this line 

 have been summed up in his recent work, The Origin of 



