Royal Astro7iomical Society. 475 



The previous return should have taken place about the year 607, 

 and the Chinese annals have several comets in that year. I find, by 

 actual computation, that none of them present any decided indications 

 of identity with the one which forms the subject of these remarks, 

 and I am therefore inclined to fix its reappearance in the following 

 year, 608, when a comet is mentioned by Ma-tuoan-lin, though 

 (most unfortunately) he has omitted to state the days to which his 

 positions apply. The path attributed to this body, from Auriga, 

 through the lower part of Ursa Major, into Scorpio, where the comet 

 vanished, is precisely that which Halley's comet must follow when 

 the perihelion takes place in October or early in November. This 

 circumstance, and the close agreement of intervals, appear to render 

 it highly probable that the Chinese observed the comet of Halley in 

 608. 



After a careful examination of the particulars related of the comets 

 of 530 or 531, which Newton and Halley, owing to the want of 

 precise data, recognised as that of 1680, I find the whole of them 

 may be explained by the elements of Halley's comet, supposing it to 

 have been in perihelion early in November. Yet this inference is 

 necessarily open to considerable doubt, and I am very far from in- 

 sisting upon it. Of one point I have become pretty well convinced 

 by my calculations, viz. that the comet of 530 or 531 (for the year 

 of appearance is doubtful) was not identical with the celebrated one 

 of 1680. Pingre seems to have suspected this, though he has en- 

 deavoured, by alteration of dates or positions, to show that such 

 identity may have been possible. Where however we find the 

 accoimts of a comet as they stand in the original authorities recon- 

 cilable with a single orbit, it is surely unfair to alter them in any 

 way, so as to produce an agreement with some preconceived notions. 



In 451, or at an interval of about 79 years from 530, a comet was 

 observed in Europe and China. It appeared about the time of the 

 battle of Chalons, when Attila was defeated by the Roman General 

 Aetius. On May 17 the Chinese saw it near the Pleiades, and fol- 

 lowed it till July 13, when it was situate near /3 Leonis. Assuming 

 Halley's comet to have arrived in perihelion on July 3 at midnight, 

 M. Laugier finds a remarkable agreement between the observed and 

 calculated positions, and there can remain but little doubt that this 

 body was seen in 45 1 . 



Seventy-eight years previous, or in October 373, 24th day, the 

 Chinese mention a comet in Ophiuchus and Serpens. Suppose our 

 comet to have been at its least distance from the sun early in No- 

 vember, we shall find it would be located in Ophiuchus on the 24th 

 of October. The account is too vague, however, to allow of any 

 definite conclusion. 



Deducting another period of 78 years, we arrive at the year 295, 

 and at this epoch I find recorded a comet in Ma-tuoan-lin's cata- 

 logue which has every appearance of identity with Halley's. The 

 path assigned by this historian is exactly represented by the orbit of 

 Halley's comet, assumed to be in perihelion at the commencement 

 of April. I passed through the lower part of Ursa Major, Leo and 



2 I 2 



