OF ARTS AND SCIENCES. 67 



Two hundred and ninety-third Meeting. 



March 16, 1847. — Special Meeting. 



The President in the chair. 



Professor Peirce communicated to the Academy the fol- 

 lowing notice of the computations of Mr. Sears C. Walker, 

 who found that a star was missing in the Histoire Celeste 

 Frangaise, observed by Lalande on the 10th of May, 1795, 

 near the path of the planet Neptune, at that date, which may 

 possibly have been this planet. 



" Shortly after the arrival of the news of the jjJiysical discovery of 

 Neptune at Berlin, on a suggestion by Mr. E. C. Herrick of its prob- 

 able identity with the Wartman planet of 1831, Mr. Walker engaged 

 in the study of the orbit of the former, and soon concluded that they 

 could not have been the same, and that no set of elements could be 

 found, with a mean distance at all probable, which would represent the 

 four places of Wartman's planet, as published in the Comptes Rendus 

 for 1836. 



" His first examination of the orbit of Neptune led to the presump- 

 tion that the orbit is nearly circular. Also, the large planets lead by 

 analogy to the same conclusion. The eccentricity of 



Jupiter is 0.048 



Saturn " 0.056 



Uranus " 0.047 



Neptune " <^ 0.060, conjectured. 

 " With a small eccentricity, it was impossible for the sun's mass at 

 that distance to impress much daily variation of the radius vector. 

 Accordingly, an approximate solution was made from the places ob- 

 served on the 26tli of September, 26th of October, and 21st of No- 

 vember, on the supposition of a constant radius vector. The conclud- 

 ed true sidereal orbital motions n', n, and n", together with the mean 

 daily sidereal motion //, for the radius vector r = the semi-axis major = 

 a, are liere given. 



8 



