OF ARTS AND SCIENCES. 137 



the existence of a ring ; but whether it is caused by a ring, or by the 

 inner satellites which probably exist, or whether it be only an optical 

 appendage, it would be difficult to determine. 



" The important object in view in these observations has been the de- 

 termination of the mean distance of the satellite, in order to ascertain 

 the mass of Neptune. For this purpose measurements near the times 

 of greatest elongation are most valuable. On five occasions, namely, 

 Nov. 26, 1847, July 3, Aug. 31, Oct. 20, and Oct. 23, 1848, the satel- 

 lite has been observed in this position. The elements of the satellite's 

 orbit from these observations, as computed by Mr. G. P. Bond, are : — 



Periodic time, 5.8752 days. 



Inclination, 30° 



Ascending node, 300° if the motion be direct. 



Passage of ascending node, 1848, Oct. 30.37, Greenwich M. S. T. 



Mean distance, 16."3 at the mean distance of Neptune. 



" These elements have been found by comparing the places of the 

 satellite computed from Professor Peirce's orbit, published in the first 

 volume of the Proceedings of the American Academy, p. 295, with 

 those observed, and thence deducing small corrections for the epoch, 

 period, and mean distance, so as best to satisfy the whole series of 

 distances. The following table shows the agreement between the ob- 

 served and computed places in the corrected orbit. 



" The corresponding mass of Neptune is = Tg-ixrTT' 

 VOL. II, 18 



