378 ANNUAL OF SCIENTIFIC DISCOVERY. 



a velocity somewhat diminished from the resistance encountered in 

 our atmosphere." 



THE GREAT COMET OF 1861. 



On the last evening of June, 1861, a comet of most remarkable size 

 and brilliancy suddenly made its appearance in the northern hemi- 

 sphere. It was at first supposed to be the celebrated comet known 

 as " Charles the Fifth's," the reappearance of which has, for some 

 years past, been expected ; but investigations soon showed that the 

 celestial visitant had probably never before been observed by astron- 

 omers. 



The suddenness of the apparition of this comet in northern lati- 

 tudes was one of the most impressive of its characteristics. On the 

 29th of June, observations at the Cambridge (Mass.) Observatory 

 failed to detect it ; but on the succeeding evening the comet was the 

 most conspicuous object in the western sky. It was, however, dis- 

 covered at Sidney Observatory, New South Wales, as early as May 

 13th, and became visible to the naked eye in southern latitudes on 

 the 27th of the same month. " On the 2d of July," says Mr. Bond, of 

 the Cambridge Observatory, " after the twilight had disappeared, the 

 head, to the naked eye, was much brighter than a star of the first 

 magnitude, if only the effective impression be taken into account, 

 although, as to intensity, it was far inferior to* a Lyrse, or even to 

 a Ursae Majoris. I should describe the head as nearly equal in 

 brightness to that of the great comet of 1858, between the 30th of 

 September and the 5th of October. 



" The aspect of the tail," continues Mr. Bond, " suggested a resem- 

 blance to the comet of March, 1843. It was a narrow, straight ray, 

 projected to a distance of one hundred and six degrees (106) from 

 the nucleus, being easily distinguishable quite up to the borders of 

 the milky-way. The boundaries, for the most part, were well defined, 

 and easily traced among the stars. Further observations on the tail 

 made it evident that a diffuse, dim light, with very uncertain out- 

 lines, apparently composed of hazy filaments, swept off in a strong 

 curve towards the stars in the tail of Ursa Major the southern edge 

 directed as low as towards Mizar. This was evidently a broad, 

 curved tail, intersected on its curved side at the distance of a few 

 degrees from the nucleus by the long straight ray, which, at the first 

 glance, from its greatly superior brightness, seemed alone to constitute 

 the tail. The two were in fact counterparts of the principal tail and 

 the supplementary rays of the great comet of 1858, with this re- 

 markable difference, that in the latter the straight rays were so far 

 inferior in brightness to the curved tail as to have been recognized at 

 only three observatories, those of Pulkova, Gottiugen, and Cam- 

 bridge, U. S. ; while, with the present comet, the predominating fea- 

 ture was the straight ray, to which the curved tail seemed scarcely 

 more than a wisp-like appendage. 



"On further scrutiny, with the aid of an opera-glass, two sharply- 

 cut and very narrow dark channels, bounding the principal ray, 

 could be traced for ten or fifteen degrees from the nucleus ; while 

 outside of them, on either side, were two additional faint rays. The 



