ASTRONOMY. 297 



length succeeded in deducing approximate elements, which showed a 

 remarkable resemblance to those of comet I, 1880, and I, 1843. 



Per. pass. = 1882, September, 17.38, G. M. T. 

 Long. (Per. - node) = 00° 45' ^ 



Long, node =342 29 J^Mean equinox, 1882.0. 



Inclination : . = 1 40 1 7 j 



Log. q = 7.54407. 



The resemblance of the orbit of the great comet of 1880 to that of 

 the still finer one of 1843 had attracted the earnest attention of astrono- 

 mers at the time, and most had been led to consider them one and the 

 same body. 



And now the appearance of a third magnificent object on the same, 

 or nearly the same, track revived the discussion which took place in 

 1880. Then three leading theories had been started. 



The first, of least probability and but little received, saw in the comet 

 of 1843 a return of the comet of 1GG8, and supposing the comet of 1702 

 to have been another return of the same object, considered that we had 

 here a comet with a period of about 35 years, which had been apparently 

 slowly increased to one of 37 years. But this theory rested on but very 

 slender foundations; and, if true, it is obvious that our present visitor 

 can claim no identity with his predecessors in the same path. Professor 

 Weiss, of Vienna, holding a somewhat simOar view, ascribed to the comet 

 a constant period of about thirty-seven years, and identified it with 

 those of HOG. 1179, 1363, 1511, and 1695, but not with that of 16G8. 



A second theory suggested that the comets of 1843 and 1880 might 

 now be independent comets traveling on the same track, the original 

 parent comet having suffered disruption at some much earlier visit, and 

 the fragments having become so widely separated that an interval of 

 thirty-seven years now takes place between their perihelion passages. 

 In any case it was felt that the hypothesis that so brilliant an object 

 could have frequently returned without any observation having been 

 made of it was quite incredible. 



A third and more popular theory regarded, indeed, the comets of 

 16G8, 1843, and 1880 as one and the same object, but supposed that its 

 period was gradually being shortened through the resistance experi- 

 enced by the comet whilst passing through the solar atmosphere at 

 perihelion. M. Meyer went farther back, and regarded Aristotle's comet, 

 B. C. 371, as the next earlier appearance to that of 1G68. This theory 

 seemed to receive strong confirmation by the apparition of the present 

 comet, and further information seemed to lend it greater force. 



The great comet which had borne the names of Thollon, Common, and 

 Cruls, who had each in turn discovered it independently, now proved 

 to have been still earlier discovered by Mr. Finlay, first assistant at 

 the Cape Observatory, who remarked it at five o'clock in the morning 



