54 Mr. Hind on the expected Reappearance of 



tions are in Eridanus during the latter part of the comet's 

 apparition; historians generally contenting themselves with 

 stating that the comet " finally traversed Orion." M. Pingre's 

 elements, which are not open to these objections, do not agree 

 so well as mine with the more circumstantial details left us in 

 the Chinese annals. The two orbits differ chiefly in the lon- 

 gitude of the node and perihelion distance, but the discord- 

 ances are by no means great. 



The results of my calculations have satisfied me that the 

 comet of 1264< was, in all probability, the same as that of 1556, 

 and consequently, that its return to perihelion must be very 

 near at hand. The nodes of the comet's orbit lie very close 

 to the earth's path. The ascending node is passed fifty days 

 before perihelion, the radius vector being 1*193, and conse- 

 quently the distance outside the earth's orbit about 0*197. 

 The passage through descending node occurs 31| days after 

 perihelion, and the distance of the point from the earth's orbit 

 inside is 0*126. However, the nearest approach of the comet 

 to the earth will not happen at the nodes, but soon after its 

 passage through them; thus in 1556 the least distance between 

 the two bodies was O'OT'i, nine days after the transit through 

 ascending node. The effect of this close proximity to our 

 globe on the period of revolution of the comet has been inves- 

 tigated by Professor Madler, of the Dorpat Observatory, as 

 detailed in No. 501 of the Astronomische Nachrichten\ it 

 amounted to 14| days only, and the return of the comet to 

 perihelion was fixed for the end of February 1 848. 



The following table contains the heliocentric co-ordinates 

 referred to the equator and the log. radii vectores of the comet 

 in my last orbit, reduced to 1848, for every tenth day, from 

 ninety days before to 90 days after perihelion. 



