NATURE 



\yune 30, 1 88 1 



Prof. Skinner found that in two days and a quarter the 

 comet moved about ten degrees. On Saturday morning 

 it became distinctly visible at i'45, and could be seen 

 until the sun rendered invisible all the stars except Venus. 

 The astronomers at the observatory maintain their opi- 

 nion that this comet is identical with the one recently 

 observed by Dr. Gould in Buenos Ayres. Prof. Skinner 

 describes it as a much finer coinet than Coggia's, which 

 appeared in 1874, and brighter than any since that which 

 appeared in 1843. 



" Prof. Newcomb said that as all the observations made 

 on the comet of 1807 showed it to have a period of nearly 

 1700 years, it seems out of the question that under any 

 circumstances the same comet could have returned in so 

 short a time as seventy-four years, unless it has passed 

 in the vicinity of some larger planets, which it could not 

 have done. From Dr. Gould's telegram it may be 

 inferred that the comet was very near the orbit of that 

 of 1807 when he observed it. Prof Newcomb is inclined 

 to think that it is a case of two comets moving in nearly 

 the same orbit, rather than the return of the same comet. 

 One reason for this is that if it had been a periodical 

 comet returning every seventy-four years, it could not 

 have failed to have been observed on former occasion'^, 

 because it would have returned in 1734 and in 1760. 

 In neither of these years was any such comet ob- 

 served. The position of its orbit is such that it could 

 hardly have failed to be seen had it returned. Prof 

 Henry Draper has photographed the comet. To 

 obtain such a photograph as he would like, he said, 

 the plate ought to be exposed for at least an hour, 

 but he had succeeded in getting an exposure of only 

 seventeen minutes. The result, however, was satis- 

 factory, in so far that it demonstrated the possi- 

 bilities of photographing a comet. It showed the 

 nucleus and the coma and part of the tail. He will 

 try again to obtain a longer exposure. He wishes to 

 take a larger photograph if possible, to examine more 

 carefully the structure of the tail ; but the larger the 

 photograph, the more difficult it is to obtain, owing 

 to the diffusion of the light. If he succeeds in ob- 

 taining two good photographs he will next turn his 

 attention to its spectrum, which is much more diffi- 

 cult to photograph than the orb itself. 



" Prof. Bois, of Dudley Observatory, at AUebuy, 

 secured a number of valuable observations. He 

 says that at two o'clock on Saturday morning its 

 appearance both to the naked eye and in a telescope 

 was magnificent. The head of the comet was very 

 bright, and the tail thirty or forty minutes broad, 

 extending nearly 20° toward the North Star. The tail 

 was very diffused and nebulous, spread out in fan- 

 like form. Looking in the great telescope of thirteen 

 inches aperture, a multitude of details became re- 

 vealed which are not visible to the naked eye. The 

 head was there seen to consist of a condensed nucleus, 

 apparently about as large as Jupiter seen in a tele- 

 scope, but of far greater intensity of light. A spray 

 of brilliant rays spread out from the nucleus on the 

 side nearest the sun, then, turning backward, mingled 

 with the elements which form the tail. This re- 

 sembled the jet of a fountain very closely in its 

 general features. The tail itself extended in a 

 direction diametrically opposite the sun. The whole field 

 of the telescope was filled with glowing nebulosity. I am 

 inclined to think that this coinet has not been seen before 

 this year, in modern times at least. It is probably the 

 same comet as seen in South America. It is now certain 

 that this is not the long-expected comet of 1882. It is 

 almost equally certain that it is not the comet of 1S07. 

 The period of the comet of 1807 is about 1,700 years. 

 Prof Swift of Rochester says the comet grows smaller 

 and brighter in nucleus, showing that it is approaching 

 the sun. The head is active, and the tail does not ob- 



scure the stars. He thinks it will be visible several 

 weeks. He cannot yet determine if the comet was ever 

 before seen. Great activity is apparent in its head." 



M. Janssen has presented to the Academy of Sciences, 

 at its sitting of June 27, the cHcJic of a photogram of the 

 comet, which was taken with the large telescope he 

 described a few weeks ago, constructed for the purpose 

 of astral photography. He obtained also a series of 

 photograms of the nucleus, for which he varied the time 

 of exposure. The results prove that the brightness is 

 not more than that of a star of the fifth magnitude. On 

 the photograph, which will be printed in NATURE, and 

 which our correspondent has examined, the stars are 

 visible through the tail. M. Faye delivered a speech 

 praising the success realised by his colleague, and re- 

 marking that it was the first time that a comet had been 

 photographed. The opinion that the tails of comets are 

 merely an illusion, as professed by Seneca in his " Quaes- 

 tiones Naturales," seems to gain ground, owing to the 

 extraordinary transparency of these appendages. 



We have received the following communications : — 

 The following positions which I obtained of the path of 

 the comet may interest your readers : — 1 saw it first on 



Wednesday, June 22, at 10.55, during a break in the clouds 

 for about a minute. It was then brighter than it was last 

 night, the 27th, when 1 saw it well, the sky being clear. 

 The colour is of an orange tinge, and the tail extends to 

 about 10°, but can only be seen so far by sweeping across 

 it. It has changed wonderfully since I first observed it, 

 as will be seen by the drawings which I send you. The 

 No. I Drawing shows a most singular appendage round 

 the nucleus, in shape like a milkmaid's yoke, the nucleus 

 occupying the hollow, which was black. From the nucleus 

 two horns projected ; they were as bright as the nucleus. 



