304 



THE MOON. 



in the meridian at midnight, and will rise as the sun sets, and set as the sun 

 rises'; and thus, whenever the enlightened hemisphere of the moon is turned 

 toward us, and when, therefore, it is the most capable of benefiting us, it is 

 up in the firmament all night ; whereas, when it is in conjunction, as at A, and 

 the dark hemisphere is turned toward us, it would then be of no use to us, and 

 is accordingly up during the day. The position at C is called the " first quarter," 

 and at G the " last quarter." The position at B is called the first octant ; D 

 the second octant ; F the third octant ; and H the fourth octant. At the first 

 and fourth octants it is a crescent, and at the second and third octants it is gib- 

 bous. 



Fig. i. 



The apparent motion of the moon in the heavens is much more rapid than 

 that of the sun ; for while the sun makes a complete circuit of the ecliptic in 

 365 days, and therefore moves over it at about 1 per day, the moon makes 

 the same circuit in little more than 27 days, and consequently must move at 

 the rate of a little less than 14 per day. As the sun and moon appear to 

 move in the same direction in the firmament, both proceeding from west to 

 east, the moon will, after conjunction, depart from the sun toward the east at 

 the rate of about 13 per day. If, then, the moon be in conjunction with the 

 sun on any given day, it will be 13 east of it at the same time on the follow- 

 ing day ; 26 east of it after two days, and so on. If, then, the sun set with 

 the moon on any evening, it will, at the moment of sunset on the following 

 evening, be 13 east of it, and at sunset will appear as a thin crescent, at a 

 considerable altitude ; on the succeeding day it will be 26 east of the sun, 

 and will be at a still greater altitude at sunset, and will be a broader crescent. 

 After seven days, the moon will be removed 90 from the sun ; it will be at or 

 near the meridian at sunset. It will remain in the heavens for about six hours 

 after sunset, and will be seen in the west as the half-moon. Each successive 

 evening increasing its distance from the sun, and also increasing its breadth, it 

 will be visible in the meridian at a later hour, and will consequently be longer 

 apparent in the firmament during the night it will then be gibbous. After 

 about fourteen days, it will be 180 removed from the sun, and will be full, and 

 consequently will rise when the sun sets, and set when the sun rises being 

 visible the entire night. After the elapse of three weeks, the distance of the 

 moon from the sun being about 270, it will not reach the meridian until nearly 

 the hour of sunrise ; it will then be visible during the last six hours of the 

 night only. The moon will then be waning, and toward the close of the 

 month will only be seen in the morning before sunrise, and will appear as a 

 crescent. 



