22 



KNOWLEDGE. 



[Januaby, 1902. 



tutcd for hair in the stiifTiiitj of chairs, etc., and such material 

 woulil form a good hreeding ground for creatures of this 

 deBcrijjtion. They require a certain amount of dampness to 

 propagate. 



Commutilcations and enquiries on Microscopical matters are 

 cordially invited, and should be addressed to M. I. Cross, 

 Knowledge Office, 326, High Ilolhorn, W.C. 



NOTES ON COMETS AND METEORS. 



By W. F. Denning, f.r.a.s. 



Periodical Comets Due in 1902.— The returns of two comets 

 of sliort jieriod may be expected during the year. Swift's comet 

 of 1895 whicli was computed to have a period of 7^ years is due 

 in the autumn, but the conditions will be less favourable than 

 in 1895. and it is probable that this object will escape rcdetection. 

 TenipelSwifl's comet will return to perihelion in November, 

 and is likely to be successfully observed a,s in 1869, 1880, and 

 1891. Its period is as nearly as possible 5J years, and the 

 circumstances favour its visibility at every alternate return 

 occurring at intervals of 11 years" In 1869 perihelion occurred 

 on November 18, in 1880 on November 8, and in 1891 on 

 November 14. On these occasions its apparent path in the 

 heavens was nearly the same, and the comet will run a nearly 

 similar course during the autumn and winter of 1902. 



Swift'.s Comet, 1899, I. — Definite orbit-elements have been 

 rompnted by Mr. 0. J. Merfield, of S.vdney [Ast. Nach. 3747-8). 

 The comet was first seen on March 3, 1899. and 605 observations 

 for position were obtained between March 4 and August 10. 

 The following are the elements deduced : — 



T = 1899, April 12, 978010 G. M. T. 



0) = %" 41' 46--18" \ 



!} = 21" 59' 59-93" [ 1900. 



i = 146" 15' 30-29" ) 



log. q = 9-5139795. 



log. c = 0-0001521. 



e = 1 0003503. 



Perrine'.s Comet, 1897, I. — The orbit of this object has been 

 investigated by Dr. J. Moller, who finds from observations 

 between November 2, 1896, and April 29, 1897, that its path 

 was decidedly hyperbolic. There appears, indeed, to have been 

 only one other comet, observed in 1889, which exhibits this 

 exceptional form of orbit in a more striking manner. 



The Leonid Shower or 1901. — The nights of November 14 

 and 15 were generally clear in this country, though fog pre- 

 vailed in some places. The meteors were attentively watched 

 for, but only a moderate number seen. At short intervals 

 a Leonid would shoot swiftly from the direction of " the Sickle," 

 but nothing in the form of a brilliant shower was witnessed. 

 At certain distant places observers appear to have been more 

 successful according to some telegraphic reports pubUshed in 

 the newspapers. Quite an active exhibition of Leonids was in 

 fact recorded at a number of stations. The information comes 

 from New York that on the early morning of November 15 

 a great shower was witnessed on board a steamer from New 

 Orleans. On the morning of November 15 at the Leander- 

 McCormick observatory of the University of Virginia, Va. , Mr. 

 C. P. Oliver, watching the sky from 4h. 50m. a.m. to daylight, 

 saw 84 Leonids, the average being one per minute in spite 

 of adverse atmospheric conditions. On the morning of November 

 16 at Phcenix, Ariz., a meteoric shower of great brilliancy was 

 noted. It continued for half an hour during which it supplied 

 200 meteors. Just before daylight on November 16, at Los 

 Angelos, Cal., the faU of Leonids was quite marked. One 

 observer counted 385 meteors between 4 and 5 a.m., but the 

 total number seen was estimated at over a thousand. From 

 these and other reports it appears certain that the recent display 

 was much richer than in 1899 or 1901, and the inference is 

 that the tail end of the stream has not been disturbed to the 

 same extent as the denser region. This leads to the hope 

 that many Leonids will be visible in November, 1902, but un- 

 fortunately there will be a full moon to mar the spectacle. 



Fireball of November 10, 6h. 45m, — Scottish observers have 

 supplied descriptions of a very briUiant meteor. At Crieff it 

 was seen in the south-east " descending rapidly, and bursting 

 into a number of rocket-like stars." At Aberdeen one observer 

 says it flashed across the S.W. sky and lit up the earth like 

 a search-light. Another observer there says that it was half 

 the apparent diameter of the moon, and so Bright as to be quite 

 dazzling, and almost like a new sun. It crossed the sky from 

 the region of a Pegasi to Altair. At Newtouhill it is 

 described as crossing the heavens from E. to W., at about 



40 degrees above the horizon, and making an angle of 20 degrees 

 with it. In colour it appeared like a quantity of burning mag- 

 nesium, and for the space of three seconds the country seemed 

 as though lit by numbers of arc lamps. At Ulairgowrie it 

 emitted an intensely bright white light, and at Ellon, N.B., 

 it was seen to burst out in Pegasus, and to travel in a direction 

 to the S.W. From these and other accounts it appears that 

 til.' nu-teor was a fine Taurid falling from a heiglit of 64 to 55 

 miles from over the North Sea to Dunning, Perth. Length 

 of path 73 miles, and velocity about 24 miles per second. 



FiRKiiALL OF NovKMiiER 13, 6n. 53m. — Another magnificent 

 nuteor was seen in Scotland at this time, but only three de- 

 scriptions have come to hand. Mr. A. C. Allen, of Keswick, 

 says it passed to the right of a Ccphei and S Cygni, and to 

 the left of 7 Lyrae, and continued it.^ (light some distance 

 further. The meteor left a nebulous cloud near y Lyrae for 

 about li minute, moving slowly to S.W. , and curving into 

 a cre.scent shape. The nucleus was accompanied throughout its 

 course by a halo of about 45 degrees diameter. At Stair 

 the meteor was estimated to have a breadth half the 

 diameter of the full moon, and it broke into two pieces. It 

 fell at any angle of 45 degrees from S.E. to S.W., and lit up 

 the sky like a flash of lightning. " It only lasted 4 or 5 seconds." 

 At Fife the meteor was exceedingly bright, of a greeni.sh white 

 colour, and it left a luminous streak for 4 or 5 seconds. It passed 

 from about the centre of the square of Pegasus to a. and /3 

 Capricorni. The radiant point was in Auriga probably at 

 87° + 34", and the height of the meteor was from about 90 to 52 miles 

 from over the Cheviot Hills 12 miles E. of Langholm to the Irish 

 Sea in longitude 5° 47' W., and latitude 53° 38' N. Path 

 about 165 miles and velocity about 33 miles per second. 



THE FACE OF THE SKY FOR JANUARY. 



By W. Shackleton, f.e.a.s. 



The Sun. — On the 1st the sun rises at 8.8 a.m., and 

 sets 3.59 P.M. ; on the 31st he rises at 7.43 a.m., and sets 

 at 4.44 P.M. The earth is at its least distance from the 

 sun at 7 a.m. on the 1st; the apparent diameter of the 

 sun then being at its ma.Kiinum, 3'2' 35"-16 ; the horizontal 

 parallax is then 8''-95, also a maximum. 



Few sunspots are to be expected. 



The Moon: — 



The more interesting occultations visible at Greenwich 

 are as indicated in the following table: — 



The Planets. — Mercury is not well situated for obser- 

 vation, being in superior conjunction with the sun on 

 tho 1st; towards the end of the month it will be an 

 evening star setting a little more than an hour after 

 the sun, but even then it is too far south for easy 

 observation. 



Venus remains an evening star and attains her 

 f/reateH hriUiancy on tho 9th. the apparent diameter 

 then being 40". Throughout the month she will form 

 a conspicuous object in the south-west shortly after sun- 

 set, and with the exception of the last few days the 



