136 FROM NEBULA TO NEBULA 



from him their fraudulent character. Then, taking a 

 perfectly true pair of dice from your pocket, hand them 

 to him and say : ' i Here, friend, is a pair of honest dice 

 for you. Let us throw for the dinners. Do you use your 

 dice, casting them in the ordinary manner in the open air, 

 but let me shake my false ones within a vacuum tube 

 pairs of sixes to win." If he is consistent at heart 

 scruples of conscience aside he should take you up on 

 the instant. But will he ! Think the matter over. 



Theoretically, it would be possible to extend the 

 original vacuum-tube experiment to the other extreme; 

 that is, we may suppose the tube lengthened to, say, ten 

 miles. In that case the act of falling would consume just 

 about one minute surely not too long to grant Nature a 

 fair chance to absolve herself from the stigma of vacil- 

 lation that Newtonians have thrust upon her. Inci- 

 dentally, we may imagine the tube capacious enough to 

 allow for the introduction of suitable micrometrical de- 

 vices to record the equilibristic gyrations of the object, 

 not only at the instant of alighting, but also in the course 

 of descent. Of course, all this is practically impossible, 

 and if Nature must await her vindication until such a 

 thing becomes practicable, she is likely to remain in dis- 

 grace until all human interest in the issue has died out. 

 Fortunately for her and us, however, she has thought to 

 set out documentary evidence of her consistency on the 

 scroll of the sky. I refer to the moon. Why, do you 

 suppose, does our satellite continually turn the same face 

 toward us, unless it is because her visible hemisphere is 

 the heavier; and why does she exhibit her librations, if 

 not because of the conflicting attractions of the sun and of 

 the Prime Eesultant? 



Now conceding solely for the sake of argument, 

 however, that the moon is really falling earthward at 

 the rate of 1/19 inch per second, then the earth, being 81 

 times heavier, must be falling moonward only 1/171 inch 

 in the same brief instant. This is tantamount to saying 

 that the earth, if falling moonward at all, is falling only 

 one inch in about 3 minutes ! Suppose that by some de- 



