86 THE BOOK OF NATURE STUDY 



as it is the western border of the full moon that darkens as the 

 moon wanes, this spot early disappears in the waning moon, 

 and does not reappear until the new crescent appears. This 

 spot is the so-called Sea of Crises (Mare Crisium), one of the 

 numerous " seas " or plains of the moon. 



The evidence upon which is based the conclusion that the 

 moon has no light of her own, but shines by the pale reflected 

 light of the sun, is based upon somewhat close reasoning, and 

 the teacher will probably find it necessary simply to take this 

 conclusion for granted when dealing with elementary classes. 

 The fact may, however, be suggested in connection with actual 

 observations, which give it more vividness and reality. Thus 

 when the full moon is riding high in the heavens on a winter 

 night, the teacher may suggest the idea of the invisible sun which 

 she is then facing, and whose glory she reflects in her pale beams. 

 She is then, as it were, the mirror which tells us that the sun which 

 we cannot see is still shining in undiminished strength. Simi- 

 larly, when the slender crescent of the new moon appears in the 

 western sky, just after the sun has sunk, we may suggest that 

 the orb, which has been invisible for some nights, is now catching 

 some of the rays of the western sun, and is thus rendered visible 

 as a slender rim, whose convex side is turned towards the dis- 

 appearing sun. 



Again, if by a chance observation a pale " crescent " moon 

 is observed at dawn, we may point out that this is the waning 

 moon, whose eastern border is illuminated by the rays of the 

 rising sun, so that the horns are turned in the reverse direction 

 from those of the waxing moon. 



It may also be possible to combine a summer and a winter 

 observation, so as to show how high the winter moon rides in 

 the heavens, i.e. how far she is to the north as compared with 

 the more southerly full moon of June, which lies lower in the 

 great arch of heaven. 



The object of the observations should be to suggest the 

 double movement of the moon in the heavens, her movement from 

 west to east, and her other movement from south to north, and 

 back again to south. The latter movement is chiefly of im- 

 portance from our standpoint in that it gives us the long moon- 



