LUNAR CHANGES. 



the first quarter, it appears as a CEESCENT, the convex side of the 

 crescent being turned westward, and towards the sun (fig. 8). 



Fig. 7. 



The crescent moves with its concave edge foremost. The unen- 

 lightened part of the moon is indicated by the dotted line in the 

 figure. 



In this phase the moon, not having yet arrived at the first 

 quarter, is less than 90 east of the sun, and the less it is removed 



w 



from the sun, the thinner is the crescent ; and the more near it is 

 to 90 from the sun, the more nearly does the crescent approximate 

 to the half moon. 



The moon being thus removed more or less to the east of 

 the sun, or, what is the same, the sun being to the west of the 

 moon, will set just before the moon ; and the more the moon is 

 removed from the sun, the longer will be the interval between 

 sunset and moonset. After sunset the moon will therefore, soon 

 after conjunction, be seen as a thin crescent in the western 

 sky, and the farther it is removed eastward of the sun, the 

 greater will be its altitude at sunset, the broader will be the 

 crescent, and the larger will be the interval between sunset and 

 moonset. 



At length, when 7 days have elapsed, and the 8th day has com- 

 menced from the time of conjunction, the moon having advanced 

 to 90 eastward of the sun, and being in quadrature, as in fig. 7, it 

 will be on the meridian about sunset, and will not set until about 

 midnight. Between sunset and midnight it will be seen to descend 

 from the meridian to the western horizon. 



47 



