60 ROUND THE YEAR 



distance, much greater than the diameter of the 

 earth's orbit, and if our point of view were in the line 

 joining the North and South Pole of the heavens, the 

 Moon might be seen to circle round the earth, while 

 both would circle round the sun. By careful obser- 

 vation of the place of the Moon in the background of 

 stars her path in space could be mapped with any 

 degree of precision that might be desired. 



We should find if the trial could be made that the 

 path of the Moon in space is so nearly identical with 

 the earth's orbit that very close observation would be 

 required to distinguish them. In its course round 

 the sun the Moon would make thirteen very gentle 

 undulations, curving outwards from the earth's orbit 

 for a very trifling distance thirteen times, and curving 

 a little within it as often. But it would require a 

 very large sheet of paper and very careful drawing to 

 make the difference apparent, for the deviation from 

 the earth's orbit would not at most exceed about J per 

 cent, that is J in. in 100 inches. (8 ft., 4 inches.) 



The times of rising and setting of the Moon are 

 influenced by the same causes which affect the times 

 of rising and setting of the sun, but not quite in the 

 same way. The Moon travels nearly along the zodiac. 

 The new Moon must rise and set nearly at the same 

 time as the sun, because she is near to him. The full 

 Moon will rise at about the same time that the sun 

 sets, and set at about the time that he rises, because 

 she is then opposite to him in the zodiac. Therefore 

 in winter, when the sun rises late and sets early, the 

 new Moon will do the same, but the full Moon will 

 rise early and set late. In summer the case will be 



