4IO 



NATURE 



[June 2, 1910 



The observations of M. Borrelly, recorded in the same 

 number of the Comptes rendiis, indicate what a splendid 

 object the comet has appeared to those situated in a 

 favourable atmosphere. " Very beautiful," " superb," and 

 " magnificent " are the descriptions applied to it as seen ; 

 at the Marseilles Observatory. The observations extended i 

 from April i6 to May 13, and many changes were noted ; i 

 on April 23 it was seen that the nucleus had a very pro- i 

 nounced red tint.' On May 4 the comet was as bright as I 

 Markab, and the tail was 15° long. A sudden transforma- ' 

 tion took place on May 13, when, for the first time, a 

 bright, straight streamer was seen to issue from the rear 

 of the nucleus, dividing, medially, the rectilinear tail, which 'i 

 then had a length of 43° ; the extremity of this tail was 

 about as bright as a sixth -magnitude star, and was situated, j 

 approximately, in the position R.A. 22h. 6m., dec. +6°; i 

 the comet was still visible in daylight. ' 



In order to escape the disadvantageous conditions obtain- 

 ing in Britain, Prof. George Forbes took a sea trip from 

 Swansea to Savona, and was rewarded by some splendid 

 views of the comet, which he describes iii the Times for 

 May 31. The observations commenced on May 15, and 

 the head of the comet was never seen, but on May 18 a 

 tail extending for 100° was watched from 2 a.m. until i 

 5 a.m. ; this was in long. 9° 38' W., lat. 38° 54' N. On 

 May 15 the 30° tail was about as bright as the Milky 

 Way, but the next morning it was fainter ; at times, how- 

 ever, it appeared to brighten. The morning (3 a.m.) of 

 May 17 found it again much brighter for fullv 50°, and 

 it could be distinctly traced for a distance of" 70°. The 

 tail was perfectly straight, and narrowed down towards 

 the extremity furthest from the sun ; across its width its 

 brightness appeared to be quite homogeneous, there being 

 no dark shade along the axis and no rifts. As compared 

 with the tails of Donati's and Coggia's comets it was. 

 so far as Prof. Forbes 's memory goes, much brighter and 

 of a much greater length. On May 18 the tail was much 

 widened at the root, where the brightness appeared to be 

 concentrated ; the narrowing from root to tip appeared to 

 be more accentuated, and the position of the axis among 

 the stars had not altered from the previous dav. 



According to Prof. Forbes, the earth was in the tail of 

 the comet on May 19,- and, from 2.30 to 3 a.m., a brighten- 

 ing near the .horizon and an illumination of the dark edges 

 of dense, black, cumulus clouds were seen by him and bv 

 the ship's officers. This was long before any trace of 

 dawn could appear, and all the observers agreed that these 

 peculiar phenomena must be due to light from the comet's 

 tail; the' ship was then in long. 7° 54' W., lat. 36° 36' N. 

 The same phenomena were repeated on the following morn- ; 

 ing. It should be noted that at the time of writing his I 

 notes (May 24) Prof. Forbes had not seen any reports, 

 concerning the cometary observations, since the S.S. 

 Kinsale \eh Swansea on May 13. 



In a letter received from Mr. G. W. Grabham, dated 

 Khartoum, May 19, the writer remarks how feeble the 

 accounts of British observations of the comet appear to 

 one who has observed it in lat. 15° 36' N. He first saw 

 it on April 19, when it was a conspicuous object, with 

 a tail broad in proportion to its length. With field-glasses 

 he could make out some 2j° or 3° of tail, and beyond that 

 there was a faint glow extending about 2° further. A 

 letter sent by Mr. Grabham to the Sudan Times caused ; 

 a number of people to wait up for the comet, and it was 1 

 easily seen by many on subsequent mornings, until it | 

 became more difficult owing to bright moonlight. After 

 the moon waned it was quite a striking object, and. on 

 the mornings of May 12 and 13, its tail stretched half- 

 way to the zenith. An article on the comet, written by 

 Mr. Grabham, appears in the Sudan Times in both English 

 and Arabic. 



Mr. Leach also sends us a further report and a draw- 

 , ing of the comet as seen with field-glasses on May 20, at 

 7.4> p.m., at Malta. On May 17 and 18 the comet was 

 well seen, except the head, which was eclipsed by a search- 

 light beam from the forts ; but the tail was seen, and. on 

 the latter date, extended to a distance of about 9^°. The 

 sketch made on May 20 shows the nucleus surrounded bv 

 a misty halo which has the shape of a pair of horns, with 

 the nucleus on the forehead. On Mav 21 about 20° of 

 tail was seen, but this faded as the moon got brighter, and 



NO. 2 II 8, VOL. 83] 



on May 22, 23, and 24 the comet was seen without any 

 signs of a tail. 



.-V number of notes on the comet appear in No. 21 

 (May 25) of the Comptes rendus. M. Eginitis records the 

 observations made at .Athens on May 18 and subsequent 

 days. On the morning of May 20 the tail was seen in , 

 exactly the same position as the previous night, and in 1 

 the evening was seen, in the telescope, as turned towards \ 

 the sun. On account of its curvature it was not seen in 

 the east on Saturday morning (May 21), but in the even- 

 ing was seen turned towards the east. M. Eginitis is of 

 the opinion that the earth's passage through the tail was 

 either greatly retarded or did not take place ; nor were 

 any signs of the head apparent as it transitted the sun's 

 disc. 



M. .Andr6 reports that the preparations for astronomical 

 observations of the passage were rendered nugatory by 

 clouds, and that the electrometers and magnetometers re- 

 corded no abnormal action. 



Acting upon M. Guillaume's suggestion, M. Georges 

 Claude attempted to trace cometary matter among the 

 residual inert gases left from the liquefaction of air. With 

 his apparatus at Boulogne-sur-Seine he is . able to treat 

 350,000 litres of air per hour, and to detect the presence of 

 one-millionth part of any extraordinary gas. Experiments 

 carried out on May 17 (4 hours), 19 (9h. to i2h., Paris 

 M.T.), 20, and 23 failed to reveal any difference of density 

 in the residue greater than the probable error of .observa- 

 tion. 



MM. Angot, Lebel, and Limb and Xanty, all report 



Apparent path of Halley's Comet, May 29-July 16. 



slight electric and magnetic disturbances registered at their 

 observatories during the computed time of the earth's 

 passage through the tail of the comet; but in no case was 

 the disturbance extraordinary, nor could, it be ' attribute*! 

 to any abnormal condition produced by the comet. 



The following is a further extract from the dailjl 

 ephemeris published by Dr. Ebell in No. 44 11 of th^ 

 Astronomische Nachrichten : — 



Ephemeris for 12/1. Berlin M.T. 

 Ua-e a (true) S'true) Date a (true) 5 (true) ' 



h. m. o , h. m „ 



June 2 ... lo o 4 ... + I 34'2 June 26 ... 10 4^0 ••• - 2 20T 

 ,, 6 ... 10 137 .. +0 23-1 ,, 30 ... 10 467 .. -2 41-8 

 ,, 10 ... 10 22-6 ... -o 25 4 July 4 ... 10 50 I ... - 3 26 

 ,, li ... to 29-2 ... - I 18 ,, 8 ... 10 53-3 ... -3 22-8 

 ,, 18 ... ID 34-5 ... I 3r-5 ,, 12 ... 10 564 ... - 3 428 

 ,. 22 ... 10 39-0 ... - I 57-0, „ 16 ... 10 595 ... -4 29 

 The estimated magnitudes decrease from i-o on June 2 

 to 4-6 on July 16, while the distance from the earth in- 

 creases from 52 to 197 millions of miles. 



The apparent path among the stars is shown on the 

 accompanying chart, but owing to its increasing apparent 

 proximity to the sun and its decreasing magnitude the 

 cornet will be observed with difficulty during the later part 

 of the ephemeris. The planets Mars and Jupiter are also 

 shown, but Mars will set at about 10 p.m. on June 25 and 

 about 25 minutes earlier each succeeding day, whilst 

 Jupiter sets at about midnight at the end of June. 



