186 FROM NEBULA TO NEBULA 



The same phenomena would have occurred, in like 

 sequence, had we imagined the body M approaching E 

 through a great distance. M might then have been pos- 

 tulated as gravitational from the start, the same as E, 

 the element of distance taking the place of our artificial 

 regulation of the gravitational intensity. Tides thus pro- 

 duced, by repelling (differentially) the water under the 

 tide-causing body, would obviously conform to the phe- 

 nomena, respecting whose " perversity " Darwin mis- 

 takenly complains. 



Let us consider a second illustration: Imagine the 

 universe blotted out save for a single cloud of aqueous 

 vapor of, say, the same mass as the moon; then, under 

 the principle of gravitation, the cloud would eventually 

 condense into a watery sphere. Suppose, again, that 

 instead of consisting of water vapor alone, it comprised 

 equal parts of mercury and water ; then there would re- 

 sult a planet containing an inner core of mercury, and, 

 around it, a concentric sphere of the lighter material 

 constituting a universal sea of uniform depth. 



We will now conceive an exactly similar planet to 

 spring suddenly into existence at a distance of ten mil- 

 lion miles away and both planets to gravitate toward 

 each other by virtue of their mutual attraction until they 

 collide. Query: What would be the nature of their 

 tidal deformations in transitu, assuming that they pos- 

 sessed no axial rotation? 



To this question present-day astronomy vaeillatingly 

 returns two contradictory answers, consistent only in the 

 respect that both are equally inimical to the principle of 

 equilibrium; which, indeed, is precisely what they are 

 meant to be. One of these answers is Newton's own, 

 namely, that inasmuch as the power that causes the tides 

 resides in the fact of rotation, there being in this case, by 

 premiss, no rotation, there could be no deformation at 

 all; hence the two spheres would arrive at their point of 

 impact as perfectly spherical as when they began falling. 



The alternative answer is that of the hypothesis of 

 statical tides, a notion which astronomers adopt without 



