530 Royal Astronomical Society. 



I have used the following values of the greater axes which are 

 slightly different from those employed before : — 

 $ = 0-38709888 

 ? = 0-72333228 



4 = 1- 



<J = 1-52369210 



% = 5-20115524 



Tj = 9-53797320 



$ = 19-18251740 

 With these data I obtain for the annual sidereal motion of the node 

 of mercury : — 



d -8>°. = - 7"'264 - 0"-0621 ja, - 3"*8665 p, - 0"-S915 ft 

 at 



- 0-0991 ft -2-2292 ft - 0-1129 ft -0-0022 ft 



If we assume Encke's second value of the mass of Mercury, namely 



4865751 ' and su PP ose H, ft> ft. ft. ft. each = °> 



then ^ik = -7"-242 - 3"'-867 ft. 



Now, according to Lindenau, the tropical motion of the node 

 from 1631 to 1802 is 42"'534 annually; hence, with a precession 

 of 50" - 21, the annual sidereal motion is 7""676, 



... _ o"-434 = - 3"-867 ft 

 ft = + o"-n. 



With the same data as before I have calculated the motion of the 

 perihelion of Mercuiy, for which I find the following expression : — 



djLo = + 5"-44335 + 2"-88796ft + 0*86099 ft 

 dt r 



+ 0"-02881 j* 3 + l"-59026,<* 4 + 0"-07604ft. 



The mass of Mercury does not enter into this expression. The 

 coefficient of ft is insensible. Supposing now ft, ft, ft, ft, each 

 = 0, 



^5= + 5"-44335 + 2"-8876ft. 

 a t 



Now Lindenau gives for the tropical motion of the perihelion 



56"-354 ; or, with a precession of 50"-21, an annual sidereal motion 



= +6"-144. 



.-. 6"* 144 = 5"-443 + 2"-888 ft 



_ -701 _ n v. 9 , 

 • n,. = = u -Jo. 



pl 2 -888 

 The node of Venus, as given in my first note, furnishes us, as- 

 suming Encke's second mass of Mercury, and neglecting the terms 

 which contain ft, ft, ft, ft. ft. with tne equation 

 _ i"-60 = - 5"- 174 ft 

 .-. ft = + 0"'31. 



