Astronomy. 133 



discovery. Notwithstanding my repeated examinations, it would be pre- 

 sumptuous in me to claim for my investigations a freedom from error 

 which the greatest geometers have not escaped, especially in the face 

 of the vastly improbable conclusion to which my analysis tends, viz. 

 that the influence of the new planet is wholly different from that de- 

 manded by the problem whose solution ledvto its discovery. It may 

 however be asked whether the attraction of Uranus might not be ex- 

 hibited in the motions of Neptune r in such a way as to modify the or- 

 bit deduced from observation, and thus to reconcile it with theory ; but 

 this question cannot be answered without further investigation." 



Mr. Walker's important discovery of the identity of Neptune with a 

 star observed by Lalande, May 10, 1795, (Vol. iii, ii Ser., p. 441,) 

 seems now amply confirmed. An examination of the original obser- 

 vations of Lalande, shows that he also observed the body two days 

 previous, but as the two observations disagreed, the earlier was reject- 

 ed, and the latter marked doubtful. The following communication on 

 the subject, by Mr. Walker, appeared in the National Intelligencer, 

 (Washington,) of June 4, 1847. 



Gentlemen, — In my letter of May 22d, announcing the confirmation 

 of my discovery of the Lalande observation of Neptune, I remarked 

 that the elements can now be completed, and that the computation of 

 Neptune's perturbations would afford the means of obtaining the pure 



elliptic orbit round the sun from the perturbed orbit presented in ele- 

 ments V. 



I have just completed this research by freeing them from the effect 

 °f the present action of the three great planets, (that of the others is 

 nearly insensible,) and am now able to offer to the public the defini- 

 tive elements of Neptune's orbit. They are as follows, referred as be- 

 fore to the mean equinox of January 1, 1847, and to mean noon 

 Greenwich : 



Elements VII. of Nept 



Perihelion point, 

 Ascending node, 



Epoch, January 1, 1847, . 

 Inclination, 



Eccentricity, . 



Mean distance, . 



Mean daily sidereal motion, 



Period in tropical years, 



1° 45' 32"-90 



129 51 13 53 



326 2 1 -34 



1 45 38 10 



0005052917 



3017775 



21 // -41144 



165y-7175 



.Elements VII. are derived entirely from the planet's recent path for 

 *ne months. The test of their correctness is, that they should repre- 

 fjt within reasonable limits the two observations of ^*™*°l* £J 

 J* and May 10th, 1795. The great pains bestowed on the jreduc ion 

 ° these observations of Lalande, by M. Victor Mauvais of t ^Institute 

 °J France, induce me to adopt his" places of Neptune forto™**^ 

 -PjMjtad in ,he CmvltS ReMus for 1847 No 6 £ -fcrrec, 



, ' m t0 ^e mean equinox of January 1, 1847. i na v« c 



for na«»ii„.. , . /„ , .• _„j u„.,„ ^nmnnrcd them with my 



Parallax 



emeris from Elements VII. The result is as follows : 



