KECENT COSMOGONIES 257 



acquired a solid crust, of uncertain thickness, capable of 

 penning up the gathering tempests within. The query 

 then arises as to just how thick that crust should have 

 been in order to meet the requirements of the situation. 



One way to dispose of this query would be to point 

 out that the very existence of such a crust, thick or thin, 

 being, by premiss, the result of cooling off, precludes the 

 hypothesizing of any such rampant interior forces at all, 

 and that, once begun, the cooling process would neces- 

 sarily continue progressively to a state of total frigidity 

 and inaction. To assert that such a decadent sun 

 harbored a thermal reserve equal to 45,000 years' solar 

 radiation, yet allowed its exterior to chill into an im- 

 prisoning shell, is a contradiction in terms. Further- 

 more, the stauncher the shell the stronger the tide re- 

 quired to breach it, supposing such an event to have 

 really occurred ; and this, as we shall see, raises up new 

 difficulties. 



Whether through inability or negligently, Doctor 

 Chamberlin discreetly refrains from citing a single con- 

 crete illustration of what relation, if any, between the 

 star's mass and its solar distance would have sufficed to 

 meet the demands of his problem; subtly leaving upon 

 the mind of the uncritical reader the impression that 

 the possible choice of combinations of these two factors 

 is practically unlimited. Let us look into this matter 

 closely : 



In the first place, we must remember that the planets 

 do not revolve around the sun with equal velocities, but 

 with velocities varying greatly with their central dis- 

 tances. Thus Mercury, the nearest planet to the sun, 

 travels some eight times faster than Neptune, the outer- 

 most. Doctor Chamberlin assumes that all the planets 

 alike simultaneously acquired their tangential motions 

 from the gravitational attraction of the passing star. If 

 this were so, why did they not all start out with prac- 

 tically the same speed? In order to make clear how the 

 planets acquired their Keplerian velocities, Doctor 

 Chamberlin ought to show us just the spot where the 



