OF URANUS AND NEPTUNE. V 



i = 0° 46' 28"'44, 



e = 0.04667938, 



which values we shall employ for the latter epoch.* 



The value of the mass according to Mr Adams, (Monthly Notices of R.A.S.,\ ol. IX. 



p. 159,) is 



1 



m = . 



21000 



, , . , , , 30686-8208296 . /l + m 



The value of the \ major axis deduced by the formula of = s6s . 256s6l2 V Y^Tr' 



where E = mass of the earth = , (Encke, Astronomische Nachrichten, No. 443), is 



389-551 



a = 19-18267909. 

 The elements of Uranus, therefore, which will be used, are, 

 Epoch Greenwich mean noon January 1, 1847. 

 e = 15° 32' 52""10, 

 ■sr = 168 11 31-1, 

 e = 0-04667938, 

 n = 42"-23311392, 

 a = 19*18267909, 



7 = 71 



n = n'j' 



see next Article, 



m= , mass of Sun being 1. 



21000 ° 



6. The elements of Neptune for the same epoch given by Mr Sears C. Walker, of the 

 United States of America, (Monthly Notices of B.A.S. Vol. VIII. p. 202), are 



e' = 328° 32' 44"-20, 

 •ar'= 47 12 6-50, 

 St'= 130 4 20-81, 

 Periodic time = 164-6181 tropical years, 



= 60125-4838 mean solar days. 



From this value of the periodic time, we shall find 



«' = 2l"*55492011. 



The mass, deduced by Professor Peirce, from Bond's and Lassel's observations on the 



satellite combined, is 



1 

 m = 



18780 



* The secular variation of e during the 46 years between i a which is due to the action of Neptune during the same 

 1801 and 1847, as well as that part of the secular variation of I period, is taken account of afterwards in Art, (57). 



