242 Prof. Challis's Obsetvaiions relative to the New Planet. 



results respecting the orbit which have been deduced from the 

 observations by calculation. 



A regular series of observations of the planet was com- 

 menced on October 3, 1846, and continued at all available 

 opportunities, partly with the meridian instruments, and partly 

 with the Northumberland equatoreal, to December 4, soon 

 after which the planet became too faint to observe on the 

 meridian on account of day-light. The observations were 

 subsequently carried on with the equatoreal to January 15. 

 The series was much interrupted by cloudy weather, parti- 

 cularly in the months of December and January. On the 

 whole I have obtained twenty-eiffht positions of the planet with 

 the meridian instruments, and twenty-five positions with the 

 -Northumberland equatoreal by means of ninety-two differential 

 observations of right ascension and as many of north polar 

 distance. The equatoreal measures were all referred to the 

 same star, No. 7648 of the British Association Catalogue, the 

 exact place of which was determined bj' sixteen observations 

 with the transit, and eight observations with the mural circle. 

 I have reason to think that the positions obtained with the 

 equatoreal are entitled to very nearly the same weight as those 

 obtained on the meridian. All the above observations I have 

 completely reduced, and have placed the results at the disposal 

 of Mr. Adams for deducing elements of the planet's orbit. 



On January 12, I had for the first time a distinct impression 

 that the planet was surrounded by a ring. The appearance 

 noticed was such as would be presented by a ring like that of 

 Saturn, situated with its plane very oblique to the direction of 

 vision. I felt convinced that the observed elongation could 

 not be attributed to atmospheric refraction, or to any irregular 

 action on the pencils of light, because when the object was 

 seen most steadily I distinctly perceived a symmetrical form. 

 My assistant, Mr. Morgan, being requested to pay particular 

 attention to the appearance of the planet, gave the same direc- 

 tion of the axis of elongation as that in which it appeared to 

 me. I saw the ring again on the evening of January 14. In 

 my note-book I remark, " The ring is very apparent with a 

 power of 215, in a field considerably illumined by lamp-light. 

 Its brightness seems equal to that of the planet itseli." On 

 that evening, Mr. Morgan, at my request, made a drawing of 

 the form, which on comparison coincided very closely with a 

 drawing made independently by myself. The ratio of the 

 diameter of the ring to that of the planet, as measured from 

 the drawings, is about that of 3 to 2. The angle made 

 by the axis of the ring with a parallel of declination, in the 

 south-preceding or north-following quarter, I estimated at 60^. 



