46 FROM NEBULA TO NEBULA 



the other, on her return journey, she correspondingly in- 

 creases it. Now, the doctrine of "persistent velocities" 

 holds that, in coming inward, the moon is endowed with 

 the occult property of gaining, not merely in velocity, 

 but in strength of persistency, or, what is the same thing, 

 centrifugal force; whereas, in going outward, the con- 

 trary is alleged to be the case. So you see that, not even 

 satisfied with demanding both uncaused rectilinear 

 motions and gratuitously persistent velocities, we are 

 asked to concede, further, that this persistency is vari- 

 able; nor that, merely, but intelligently so! Moreover, 

 every planet, every satellite, every asteroid, every comet, 

 every circulating body throughout the universe of matter, 

 we are asked to believe, is blessed with a similar occult 

 power, each with a special rectilinear velocity, and a 

 unique rate of increase and diminution, to suit the mathe- 

 matical elements of its individual orbit and the exi- 

 gencies of Newtonian theory. 



Thus, after long and arduous beating about the bush 

 the astronomers have come back to the same point from 

 which they started, flushed with pride at being able to 

 tell us the illuminating news that they have discovered : 

 that the planets got started of themselves, that they 

 maintain and vary their speed by virtue of some secret 

 unfathomable power, and that, in short, the whole busi- 

 ness is quite as inexplicable as we at first found it to be ! 

 How sad to think that Kepler had to die in his "ignor- 

 ance ' ' ! 



Again, Newton concentrated his whole attention on 

 the fact that the moon falls from her tangent a trifle of 

 1-19 inch per second, equivalent in a lunar month of 2,551, 

 400 seconds to scarcely two miles ; but he and his fol- 

 lowers pass over, with but scant attention, the vastly 

 greater variation in her altitude above the earth as be- 

 tween perigee and apogee, when, in only one-half the 

 elapsed time, she rises the enormous amount of some 31, 

 000 miles, or 130 feet per second as against the 1-19 inch 

 that she falls by gravity ! and this in the very teeth of 

 gravity! Later, on the return journey, she loses this 

 again, falling, now, 30,000 times as fast as she falls by 



