SCIENCE. 



COMET B, 18S1. 



With the drawings of the above comet we received 

 from Professor Edward S. Holden the following letter: 



Washburn Observatory, ) 

 Madison, Wisconsin, > 

 July 9, 1881. ) 



To the Editor of " Science."' 



My Dear Sir — As you request, I send you with this, 

 the drawings of the head of the bright comet which have 

 been made here. The 15^-inch equatorial, with the 

 zone eyepiece (field 25'. 5, power 145), has been used. 

 The drawings have all been made by me, and in them 

 the darker the shading, the brighter the corresponding 

 part of the comet. 



Very sincerely yours, 



Edward S. Holden. 



description of illustrations. 



Figure 1. June 24, 18S1, I4h., m. t. 



" 2. " 25, " ioh., m. t. Hazy and 

 outlines of comet not well seen. The drawing shows 

 only the structure of the head. The nucleus is not 

 round, and is eccentric in the envelopes. 



Figure 3. June 26, 1881., nh.. 22m., m. t. Hazy 

 and clouds. The dark semi-circular line in upper part 

 of nucleus represents a dark part. 



Figure 4. June 27, 1881, 13b., m. t. 

 5. " 28, " • ioh., m. t. 

 " 6. " 29, " 9h., 30m., m. t. 

 " 7. July 8, " ioh., 35 m.— Moonlight. 

 The nucleus is not double. There is a dark, narrow 

 channel between the following side of the nucleus and 

 the envelopes, as in the figure. 



Figure 8. July II, 1881, 9V1., 30m., m. t. — Strong 

 moonlight and twilight. — In this figure, which is engraved 

 differently to the others, the white part represents light, 

 and the shading darker portions. 



Figure 4. 



Advices from Europe state that this comet was ob- 

 served by Dr. Elkin, of the Royal Observatory, Cape of 

 Good Hope, who states that after a week of overcast sky 

 the comet was found there on May 31. Mr. L. A. Eddie. 

 F.R.A.S., of Graham's Town, saw it on May 27, and 

 others claim to have seen it two days earlier. On June 4 

 the tail was 6° long, coma 20 minutes, and nucleus 20 

 seconds in diameter ; the comet was as bright as a 

 Columbas. 



Mr. William Huggins states that " On Friday night, 

 ("June 24) I obtained, with one hour's exposure, a photo- 



graph on a gelatin plate of the more refrangible part ot 

 the spectrum of the comet which is now visible. This 

 photograph shows a pair of bright lines a little way beyond 

 H in the ultra-violet region, which appear to belong to the 

 spectrum of carbon (in some form) which I observed in 

 the visible region of the spectra of telescopic comets in 

 1866 and 1868. There is also in the photograph a con- 

 tinuous spectrum in which the Fraunhofer lines can be 

 seen. These show that this part of the comet's light was 

 reflected solar light. 



Figure 3. 



This photographic evidence supports the results I ob- 

 tained in 1868, showing that comets shine partly by 

 reflected solar light, and partly by their own light, the 

 spectrum of which indicates the presence in the comet of 

 carbon, possibly in combination with hydrogen." 



The following spectroscopic notes, by W. H. M. 

 Christie, of the Royal Observatory, Greenwich, will be 

 read with interest : 



With the Sheepshanks equatorial (6J inches aperture) 

 the head showed the want of symmetry that has been re- 

 marked in some other comets. On June 24 the preceding 

 s : de was much the brighter, there being a strong brush or 



Figure 8. 



arc of light on that side, with a bright fan close to the 

 nucleus and a much smaller arc on the following side, 

 the two arcs appearing to spring from the nucleus on 

 opposite sides, and higher up to interlace. A very re- 

 markable feature was a straight wisp of light extending 

 from the nucleus nearly along the axis of the tail. On 

 June 25 this had become much less striking, and the 

 appearance of the head had entirely changed. The follow- 

 ing side was then much the brighter, and the general ap- 

 pearance was that of a parabolic envelope, with a much 

 brighter unsymmelrical parabola placed within it, the 

 latter having its focus on the following side of the nucleus, 

 and its axis turned round in the direction tip j / from 

 that of the tail. 



