the Semi-axis Major of the Moon's Orbit, 341 



and it is sufficient to take 

 d 



8c d°~R _8c 

 n d e d c # ;z 



a« i /. d 2 i? /> ,. an. \ 



f(d*R\Sa /d»JZ\ j 

 iVdadc/ a?* T V dc* / a 



/ d* .R \ 8 a> / d 8 Jg \ 8y / d 2 ig \ 3jn 



\d co d c) a n \dy dc) an \d a d c) a n] ' 



This equation is similar in appearance only to the equation (A) 

 of Poisson, p. 259, for the quantities 8 a 9 8 c, 8 c, &c, are here dif- 

 ferently defined, 



I omit here all consideration of the terms 



because the proof which Poisson has given in his Memoire sur le 

 Mouvement de la Lune, is completely satisfactory with reference to 

 them. 



Si s* 



In the terms — , — , &c, it is necessary to consider the va- 



an an J 



riation of the quantities [a, «], [c, w], &c, and also that of the 



f i uantit y Ok) 



, 1 _ d a dn _ da di2, 



a n~ na 2 na*~~ 2na 2 ~ pdc ' 



d e contains the term 



which may be taken as a type of others ; 

 a nJ u J \ a co / J an \doo / 



