ASTRONOMY* 135 



With the first, it will make an angle of 1* 30' $ 

 and with the second an angle of 5 9'. 



This curious fact was observed by CASSINI. LA 

 GRANGE has explained it from the theory of gra- 

 vity. 



SECT. VIII. 



ECLIPSES OF THE SUN AND MOON. 



137. THE Sun and Moon are both subject to 

 occasional obscurations, most frequently partial, 

 but sometimes also total, which are called Eclip- 

 ses. 



138. The Eclipses of either of these lumina- 

 ries happen only when the moon is near her 

 nodes ; that is, either in the plane of the eclip- 

 tic or near it. Those of the sun happen only 

 at new moon, or when the moon is in conjunc- 

 tion with the sun : the eclipses of the moon, 

 again, happen at the full moon, or when the 

 moon is in opposition to the sun. The three 

 bodies, then, the Sun, the Earth and Moon, are 

 always nearly in the same straight line when an 

 eclipse happens ; and conversely, when these 



three 



