250 FROM NEBULA TO NEBULA 



cold and the warm periods. In the pursuit of this object, 

 he informs us, was he led "into the cosmogonic fens and 

 fogs," whence he emerged with this Planetesimal Hy- 

 pothesis as his quarry. 



Like Professor Bickerton, Doctor Chamberlin de- 

 rives the solar system from the accidental meeting of our 

 ancestral sun with another star ; but with this difference, 

 that whereas the former postulates actual collision, the 

 latter contemplates only "approach to within effective 

 tidal range". He pictures the sun as formerly a solitary 

 star, moving under the head of its so-called proper 

 motion, being fortuitously met or overtaken by just an- 

 other such star as himself. Beginning by degrees to feel 

 the effect of their mutual attraction, the pair quickly ac- 

 celerated their approach, and in the natural course of 

 events whirled once around their common center of 

 gravity and then escaped from each other along hyper- 

 bolic paths. This incident he supposes to have occurred 

 so long ago that the strange star has had sufficient time 

 to lose itself among the other stars near us. 



Coincidently with their thus drawing toward each 

 other, our author conceives the visitor as having raised 

 tides upon the sun (which may or may not have originally 

 possessed axial rotation) and thus stimulated the erup- 

 tive tendency which observation reveals to be natural 

 with him, and perhaps with stars generally. When the 

 distance between them was still great, the tides, he 

 opines, were necessarily feeble and the eruptive stimulus 

 correspondingly faint ; but later on, as the point of peri- 

 helion was neared, the tides increased to a high level and 

 the accompanying eruptions became commensurately 

 more terrific in their intensity, causing the sun to shoot 

 out great bolts of viscous matter through the tidal cones 

 located at the opposite ends of his diameter. While these 

 bolts were thus in the act of rising, or hung suspended in 

 space at heights ranging from zero to some three billions 

 of miles (Neptune's orbit), they were drawn forward by 

 the attraction of the passing star. Such matter as for 

 any reason was deflected only slightly in this manner fell 



