Prof. Challis's Observations relative to the Ne'co Planet. 245 



The eccentricity of tlie orbit cannot exceed 0'18. The 

 most probable vaUie is 0*06, which differs but little from the 

 eccentricities of the orbits of Jupiter, Saturn and Uranus. 



The most probable longitude of perihelion is 4-9° 5S', and 

 the probable true anomaly 276° 43', according to which the 

 planet is near the extremity of the latus rectum and is de- 

 scending towards perihelion. These results are extremely 

 uncertain. 



The mean distance is 30"35, with a probable error of 0*25 ; 

 and the corresponding sidereal period is 167 years, with a 

 probable error of about two years. It is remarkable that the 

 periodic time is very nearly double that of Uranus ; so that 

 these two bodies will offer an instance of mutual perturbations 

 of large amount, differing in character from those of the other 

 planets, but analogous to the mutual perturbations of the first 

 and second, and second and third satellites of Jupiter. 



According to Bode's law of the planetary distances, the 

 mean distance of the new planet should be nearly 38. The 

 actual mean distance differs so much from this, that we are 

 compelled to conclude that this singular law, which holds with 

 reference to the other planets, fails in this instance. 



Since the apparent diameter of the new planet is to that of 

 Uranus nearly in the ratio of 3 to 4, according to the foregoing 

 determination of the distance its bulk is to that of Uranus in 

 the ratio of 8 to 5. 



The above is the sum of the results derivable from the first 

 series of observations. For further and more exact informa- 

 tion we must wait till the planet emerges from the solar rays. 

 Before concluding this report, I am desirous of saying a few 

 words resjiecting the 7iamc of the planet. I recently liad the 

 satisfaction of receiving from M. Struve the copy of a commu- 

 nication read by him at the general annual meeting of the Im- 

 perial Academy of Sciences of St. Petersburg, on December 

 29, in which he states the reasons that have induced himself 

 and the other Poulkova astronomers to adhere to the name 

 of Neptune, which name was first proposed by the French 

 Board of Longitude, shortly after the discovery of the planet. 

 These reasons are tiius briefly expressed in a note addressed 

 to me personally: " The Poulkova astronomers have resolved 

 to maintain the name of Neptune, in the opinion that the name 

 of Le Verrier would be against the accepted analogy, and 

 against historical truth ; as it cainiot be denied that M. Adams 

 has been the first theoretical discoverer of that body, though 

 not so happy as to effect a direct result of his indications." 

 M. Struve's communication has been published in this coun- 

 try by the Astronomer Royal, who has expressed his assent to 



