262 



KNOWLEDGE. 



[NoVEMBEB, 1902. 



Bcrtrand's lens, etc., from the body, .ind substitute for the 

 polnrisor an achromatic condenser. 



ir. /•'. N. — Tf yon .succeed in using 30ur aclu'omatic condenser 

 satisfactorily with the limited means at your dispos;iI, it can 

 only be at the cost of infinite care and patience. It must l)e 

 recognised that to use a condenser of large aperture etKciently 

 it requires as much care in adjusting as an objective of large 

 aperture. You ought, therefore, to provide yourself with a rack- 

 work focussing substage, with centreing screws to make the 

 condenser quite true with the objective ; a simple sliding tube is 

 really not enough for good work. 



Communications arid enquiries on Aficroscopical matters are 

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

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



NOTES ON COMETS AND METEORS. 



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



Pkrkink's Comet (1902 b). — This object was very favourably 

 visible when near the zenith in the clear moonless evenings during 

 the early part of October, but, though pretty conspicuous to the naked 

 eye, it never developed into a really large and imposing comet. 

 Bapidly traversing a path which successively carried it through the 

 stars of Perseus, Cassiopeia, Cepheus, and Cygnus, and thence to the 

 S.W., it entered the equatorial constellation Ophiuehus on about 

 October 17th. On November 1st the comet will be situated about 43" 

 east of the eun, and will set about 3J hours after that luminary. 

 About an hour after sunset the comet will be placed some 23° above 

 the S.W horizon, and may be found 4° N.W. of the star ji. Ophiuclii 

 (mag. 4'7). On November 3rd the object must be looked for 4° W. 

 of the star. On November 9th it will be ^een about .5" N. of 

 ■n Ophiuchi (mag. 2'6). The comet will exhibit a perceptible decline 

 in brightness from night to night (while its apparent motion in the 

 firmament will become markedly slower), so that when moonlight 

 strongly interferes with observation after the first week in November, it 

 will practically disappear as a suitable object for ordinary telescopes. 



Pall op a Meteorite in Ieeland. — On S'j;tember 13th, at about 

 10.30 a.m , some men at Crosskill, Crumlin, Co. Antrim, were working 

 in a field when they heard a noise caused apparently by some explosion, 

 and this was succeeded by a sound similar to that of escaping steam, 

 or a train on the line, only much louder. On looking in the direction 

 from whence the sound proceeded, the men saw something descending 

 with lightning speed into the wheat field adjoining, and portions of 

 the soil were thrown up a considerable distance into the air. Mr. Andrew 

 Walker, on whose farm the meteorite alighted, says it fell vertically, 

 for it made a perpendicular hole, and the corn standing round was not 

 disarranged in any way. The stone was quite hot when taken from 

 the hole about a foot and a half below the surface. It was an 

 irregularly shaped mass of a dark metallic eolom-, slightly tinged with 

 Bometliing like gold. There was a piece broken off, apparently at an 

 earlier date, and was about nine and a half pounds in weight. It was 

 cracked, probably by contact with a large field stone which it met with 

 on embedding itself in the soil. Mr. L. Fletcher, of South Kensington, 

 visited the spot, and piu-chased the meteorite for the British Museum, 

 80 that we may expect to hear more particulars of the interesting 

 phenomenon. 



Fireballs. — These brilliant objects were very numerous in August 

 and September, and the following are brief references to a few of the 

 most important ; — 



August 20, lOh. 31m., G.M.T.— Fireball lit up the sky with a glare 

 which dimmed the light of the full moon. Patli from 245° + 22° to 

 210° + 12°. Duration, three seconds. — Rev. W. F. A. Kllison, 

 Enniseorthy. 



August 22, 6h. 35m. — Large meteor as bright as the moon seen at 

 Trinidad, W. Indies. It appeared in Capricornus, and shot to Coma 

 Berenices. — Newspaper account. 



August 24, 7h. Ora.— Brilliant meteor observed at Colombo, passing 

 from N. to S., and bursting into a blaze of light. The dnzzling flash 

 terrified the natives, and served to enhance the apprehension regarding 

 the earthquake and similar disasters prophesied by Indian astrologers 

 for the end of the month. — Newspaper account. 



August 25, lull. 31m. — Fine meteor exceeding the lustre of Venus. 

 Path from about 260° + 83° to 163° + 43°. Duration 2-1 seconds.— 

 T. \V. Backhouse, Scaton Carew, near West Ilartlepool. 



August 2(i, 151i. 13m. — Fireball brighter than Venus shot from 

 305° + 40° to 290° + 15°, and left a streak for IJ minutes.— 0-. M. 

 Knight, London. 



September 6, 8h. 30m. — A magnificent meteor seen from the 

 £ngUsh Channel, London, and Shropshire, but not very exactly 

 recorded. 



September 12, 131i. 47Ju). — Meteor equal to Sirius soared slowly 

 across the Bouthern sky, tnn'crsing a path of about 46" in 3J eeronils. 

 I'osition 3.'iO° + 301° to 3(H!" + 18°, and radiant near the eastern 

 horizon between y.'i'+2'' and 103°-.'')".— Prof. A. S. ller-chel. Slough. 



Si'pt«mbcr 19, lOli. — Tl<*markahly large meteor appeared in the 

 N.W., not very far above the horizon, and remained visible about 

 half a minute. It had a pear-shaped head, and fell almost vertically. 

 — The Hon. Cordelia Leigh, Kcnilwortli. 



September 25. 7h. 35m. — Brilliant flashing fireball observed by th • 

 Rev. W. F. A. Ellison, Enniseorthy, and also by the writ«r at Bristol. 

 The former recorded tlie path as from 340" -f 31° to 350° + 17°, while 

 the latter gave it 211° I- 41° to 204° •*- 38i°. The radiant was at 

 25.5° -f 46°, and the height of the meteor 88 to 57 miles over the sea, 

 between Cardigan Bay and the St. George's Channel. The length of 

 the luminous course was about 34 miles, which it must have traversed 

 with very exceptional velocity, for .Mr. Kllison estimated the duration 

 of flight as certainly not more than one-eighth of a second ! At 

 Bristol the actual descent of the meteor was not seen, but the flash 

 caused the observer to look upwards, and the path was recorded by 

 the transient streak. 



September 27, 7h. 42m. — Large meteor brighter than Venus, seen 

 by Rev. W. P. A. Ellison, at Enniseorthy, moving from 290° -f 3° 

 to 298° — 7°, and lighting up the country. Duration \h seconds. 

 This object was also observed by Mr. A. SulUvan, of Dundrum, Co. 

 Dublin, with a path from e Aquari to within half a degree of Jupiter. 



THE FACE OF THE SKY FOR NOVEMBER. 



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



The Sun. — On the 1st tlie sun rises at 6. -54 and sets 

 at 4.33 ; on the 30th he rises at 7.43 and sets at 3. .54. 

 The equation of time is at maximum on the Srd, when the 

 sun is 16m. 20s. before the clock. 



Sunspots may be looked for. 



The Moon: — 



The moon is in apogee on the 5th, and in perigee on 

 the 17th. 



The following are among the more interesting occulta- 

 tions visible at G-reenwich : — 



The Planets. — Mercury is a morning star, and is near 

 a. Librae on the 20th. He attains his greatest westerly 

 elongation of 18° 50' on the 4th, when he rises about 

 5 A.M., the diameter of the planet is then ti"'8. 



Venus is praetically unobservable, being in superior 

 conjunction with the sun on the 29th. 



Mars is becoming more conveniently observable. About 

 the middle of the month the planet rises half-an-hour 

 after midnight and his path is situated in Leo. On the 

 17th he will appear in the same field of view as the fourth 

 magnitude star ^ Leonis. The diameter of the planet is 

 increasing, being now about 5"'5, whilst 0"91 of his disc 

 appears illuminated. 



Jupiter can be observed during the early part of the 

 evening ; at the beginning and end of the mouth he is on 

 the meridian at 6.5 p.m. and 4.26 p.m., and is therefore 



