474 Royal Astronomical Society. 



The preceding appearance of the comet should fall about 837, in 

 which year a most splendid comet was observed both in Europe and 

 China. The elements of this body, calculated by Pingre, exhibit a 

 general similarity to those of Halley's comet, with the exception of 

 the node, which is almost diametrically opposite. Now Pingre con- 

 jectured, as he himself states, that the comet passed the ascending, 

 and not the descending node on the 1 0th of April, or otherwise it 

 could hardly be said to move in a north-west direction on the 12th, 

 as we learn from the Chinese relation. It is clear, from the position 

 of the tail on the former date, that the head of the comet could not 

 have been far from the ecliptic ; and it appears to me that Pingre's 

 conclusion is unavoidable, if we take into consideration the whole of 

 the Chinese description, notwithstanding its laxity as regards the 

 distances of the comet from the equator, and the singularity of the 

 circumstance that a comet should have become visible in the very 

 year when Halley's would probably return to the perihelion, pre- 

 senting in every element except the node a striking resemblance to 

 the orbit of that interesting body. The comet of 837, which figures 

 in our catalogues, was therefore in all probability different from 

 Halley's, though the position and distance in perihelion and direc- 

 tion of motion were the same, and the inclination of the orbit (a 

 most uncertain element in the present case) not very widely different 

 for the two bodies. 



The Chinese annals mention another comet in May and June 837, 

 which was probably that of Halley. It is not unlikely that suc- 

 cessive copyists have altered the original description of the path 

 amongst the stars, and that the comets observed in Gemini and Virgo 

 in these months were the same. For the Chinese accounts of the 

 apparent tracks of comets present frequent instances of want of 

 chronological arrangement : thus a date is occasionally mentioned 

 as the epoch of discovery, and a position corresponding to a subse- 

 quent time immediately follows. If we may interpret the Chinese 

 description, so as to place the discovery of Halley's comet in Gemini 

 on April 29, and to refer the positions in Leo and Virgo to that body 

 at a subsequent date, it will be easy to reconcile the apparent path 

 with calculation, supposing the perihelion passage to have occurred 

 early in April. 



If the comet of Gemini and Leo was not that of Halley, probably 

 this object was missed altogether at this return. 



M. Laugier has shown in the most satisfactory manner that the 

 observations of the comet of 760 in Europe and China are perfectly 

 represented by the orbit of Halley's comet, tbe perihelion falling on 

 June 11. This year accords witlu my intervals. The return of the 

 comet in 760 appears to me little, short of a certainty. (Comptes 

 Rendus. 1846, July 27.) 



In September and October 684 a comet was seen in China in the 

 western heavens ; but no further particulars are given. If Halley's 

 comet reached its point of least distance from the sun in October, it 

 might have been observed in this position in September and the 

 early part of October. 



