ASTRONOMY. 101 



The series is here, and in the preceding case, adap- 

 ted to the computation of x from the perigee. 

 When x is computed from the apogee, the signs 

 of the terms involving the odd, multiples of x> must 

 be changed. A small part of this series will give 

 the radius vector in the case of the sun, with suf- 

 ficient accuracy ; we may suppose 



r = 1 +r- a cos x e* cos 2 x. 



. Though the eccentricity is supposed to 

 be found, from QJ. 9 it must be corrected by 

 means of the greatest equation of the centre, 

 determined by observation ; this equation being 

 called g, if 



g = 

 57.29578 2 768 983040 



As h is very small in the sun's orbit, being r= .038629, 

 e = - h nearly; that is, e = .016814. 



Syst. du Monde, p. 116. 5 BIOT, Astron. Phys. 

 torn. ii. p. 228. 2d edit. 



a. The greatest equation itself is found by observing 

 the sun's place in the ecliptic, day after day, and 

 comparing it with the mean place, calculated as 

 in 99. b. 



103. Astronomical 



