Mr. Walker has also furnished the comparison of the ephemeris with the 

 normal places, derived from all the observations yet received. 





DATE. 



OBSERVATION 



—EPHEMERIS. 

















For R. A. in arc. 



No. ofObs. 



For Declination. 



No. of Obs. 







A a 





A 8 





1795, 



May 9 



II 



+ 0.20 



2 



+70.55 



2 



*1845, 



October 25 



+ 3.40 



1 



+ 2.38 



1 



1846, 



September 26 



— 0.21 



160 



+ 0.55 



144 





November 6 



+ 0.11 



343 



+ 0.62 



297 





December 31 



+ 0.95 



90 



+ 0.92 



80 



1847, 



April 6 



+ 0.42 



15 



— 0.18 



16 





August 22 



— 0.64 



76 



+ 0.19 



71 





November 8 



— 0.96 



46 



+ 0.77 



51 





December 18 



— 0.44 



18 



+ 0.89 



18 



1848, 



August 24 



— 0.66 



103 



+ 0.28 



97 





November 10 



— 0..56 



103 



+ 0.28 



91 



1849, 



August 26 



— 0.74 



20 



— 0.23 



20 





November 12 



— 0.55 



39 



— 0.73 



41 



Having, in the first quotation from Lindenau's paper, introduced the men- 

 tion of the theory of Uranus, it may be well to add a word on that subject. 



Professor Peirce, in a communication to the American Academy, made on 

 the 4th of April, 1848, announced that he had completed his investigation into 

 the action of Neptune upon Uranus, from which it appeared that, with the mass 

 of Neptune deduced from Mr. Bond's observations of Lassell's satellite, the the- 

 ory of Uranus was then perfect, and that the motions of this planet did not indi- 

 cate that there was any other unknown source of perturbation. 



But there is " considerable uncertainty in the determination of the mass of 

 Uranus, which still fluctuates, notwithstanding the most recent observations. It 

 is so difficult to make accurate measin'es of the elongations ol" the satellites, on 

 account of their faintness, and of their being seen only under very favorable cir- 

 cumstances of position and atmosphere, that the value of the mass derived from 

 the most recent observations by Lassell and Herschel, of two interior satellites, 

 varies between j^^ and ajgeo- Mr. Adams, for whose labors this element is of 

 great importance, finds, by a new reduction of the observations of Lassell, goigvi 

 and of those of Herschel, snei, and thinks accordingly, that a mass of 3I005 would 

 approach nearest to the truth." (Lindenau, Suppl.) 



Professor Peirce, in his second approximation to the theory of Neptune, 

 adopted the mass of Uranus taken from Lament's determination by the observa- 

 tion of the satellites. But the mass remains to be determined anew, as he has 

 already stated, by a study of the perturbations produced by Uranus in the orbits 



Lamont's Observation in his 2ones, discovered by Mr. Hindi 



