120 



THE ORBIT OF URANUS. 



But, if we take only the stars near Uranus, with which the latter was necessarily 

 most frequently compared, the corrections will be negative. Comparing the con- 

 cluded positions of the stars from a Serpentis through O 1 ' to ft Orionis, we find the 

 following mean corrections : 



In right ascension, O'.0l2; in declination, 0".09. 



In subsequent years it is stated that the adopted positions of clock stars used 

 each year are derived from the right ascensions observed at Greenwich, Cam- 

 bridge, and Edinburgh, during the year or the two years preceding, without any 

 statement whether corrections were applied for difference of equinoxes. In some 

 subsequent years the following corrections are deduced, sometimes from the adopted 

 and sometimes from the concluded positions : 



1837, Aa = O'.OOO ; 



1840, Aa = +0.015; A Dec. = (T.OO; 



1844, Aa = +0 .070 ; A Dec. = +0 .49. 



Paris. 



All the positions of planets given by Le Verrier, in his "Annales de I'Observa- 

 toire Imperial de Paris: Observations" depend both in right ascension and N. P. D. 

 on his adopted positions of fundamental stars, the corrections to which have 

 already been given. As the corrections to the individual star places used by 

 Le Verrier are not generally of a systematic character, the general mean correc- 

 tion is employed, which is : 



In right ascension 0'.024 -f 0\0857; 

 In declination -f-0".12 +1'MT, 



T being the fraction of a century after 1800. 



In 1854 a new and larger catalogue was introduced, and for this and the follow- 

 ing years the correction in declination is derived from Auwers' tables. 



A summary of the adopted corrections after 1830, as deduced from the pre- 

 ceding comparisons and discussions, is given in the following table: 



