PLANETARY MOTIONS 45 



A little sober reflection ought to convince anyone that 

 attempts to solve the problems of the cosmos by adopting 

 in the outset a group of "laws" transcending, and even 

 contradicting, human experience, and, with these as a 

 base, trying to harmonize celestial phenomena in other 

 respects interpreted by mundane standards must prove 

 abortive. Natural law is consistent with itself from the 

 greatest to the least; pervert one part of it and you in- 

 volve yourself in an endless maze of error. Were the 

 matter less serious, it would be amusing to note the airs 

 assumed by astronomers at having "discovered" this 

 supposed departure of celestial from terrestrial me- 

 chanics this inconsistency of Dame Nature, the chief of- 

 fender of her sex. Thus, the late Miss Mary Agnes 

 Clerke, the celebrated English astronomer (Modern 

 Cosmogonies, p. 10) says naively: "Kepler's ignorance 

 of the laws of motion precluded him from the conception 

 of velocities persistent in themselves, and merely de- 

 flected from straight lines into curved paths by a constant 

 central pull. ' ' Let us, if you please, look into this ' ' con- 

 ception of velocities persistent in themselves" before we 

 decide whether to prefer to be ignorant with Kepler or 

 wise with Miss Clerke and the rest of Newtonians. 



As you, of course, know, the moon travels around our 

 earth, not in a perfect circle, but in an ellipse ; of which 

 latter the earth occupies the focus. The long axis of this 

 ellipse is called the major- and the shorter the minor axis. 

 The difference in the length of the semi-major axis and 

 the semi-minor is 1550, but the difference between the 

 longest distance of the moon and its mean distance is, 

 in round numbers, 14,000 miles, while the shortest dis- 

 tance, or when the moon is at perigee, is by even a larger 

 amount smaller ; the exact distances, according to Neison, 

 being 252,972, 238,840, and 221,614 miles respectively. 

 Now, there is one way, and but one, whereby you can di- 

 vide this orbit into exactly similar halves (at the same 

 time severing the earth in half) and that is, by slitting it 

 along the line of the major axis. Along one of these 

 semi-orbits, the moon, proceeding from her perigee to 

 her apogee, constantly decreases her velocity ; while along 



