316 OUTLINES OF NATURAL PHILOSOPHY. 



In these computations, the compression is We 



have seen that its true value is . The quan- 



tity of the precession diminished in this ratio is 



319. The Moon produces a similar retrogra- 

 dation in the intersection of the equator with 

 the plane of the lunar orbit, which, being pro- 

 portional to the cosine of the inclination of these 

 planes, is subject to continual variation ; but the 

 mean quantity of the precession which is thus 

 produced, relatively to the ecliptic, is the same 

 as if the Moon moved in the plane of that circle. 



LA PLACE, Systeme du Monde, liv, 4eme > chap. 13. 

 p. 271. 2de edit. 



If the precession due to the Sun's force be 1 5". 3, that 

 which is produced by the Moon is 35 /; ; which is 

 to the former nearly as 7 to 3. If the effect of 

 the Sun were reduced to 12.5, that of the Moon 

 would be triple of it, which is agreeable to the la- 

 test results deduced from the theory of the tides, 

 as will be seen in the next section. 



320. The 



