94 



KNOWLEDGE 



[April, 1902. 



II. (1. B. — The specimen you have sent can har.lly be Fluntra 

 rhiirtareo', its this species is but 1 J ' ' in height, and is distinguished 

 by its small size ; it is more likely to be Flimtra securifraiis 

 (Pallas), anil follo\ve<l by llincks. 



(/'. /'. — The simplost andijuickest means of measuring objects 

 under examination is with an eye))iecc micrometer dropped into 

 the eyepiece to rest on the diaphragm. The value of the lines 

 of this micrometer have first to be taken from a stage micrometer 

 with the objective and eyepiece in use. The blue glass that 

 you use, from the point of comfort is quite sufficient. The 

 object of the green glass is to render the illumination approxi- 

 mately monochromatic. Provided the glass is fairly free from 

 bubbles, &c., there is no reason why it should not be placed 

 immediately beneath the condenser. A stand is necessary when 

 liipiid filters or combinations of coloured glasses are used. 



./. H. A. — The objectives you mention by Bausch and Lomb 

 are thoroughly good, and you would be quite satisfied with them 

 for general work. 



Communications and e>iquiries on Microscopical matters are 

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

 Knowledoe Office, 32G, High Holborn, W.C. 



NOTES ON COMETS AND METEORS. 



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



Comet T. 1898. — Herr Adolph Hnatek, of Wien, has computed 

 definitive elements for this comet which was discovered by Giacobini 

 at Nict> in 1898, June .8. During the months of June, July and 

 August, 94 observations were obtained. The comet appears to have 

 been revolving in an eUiptical orbit of great excentricity, tlie com- 

 puted period being 42,043 years (Ast. Nach., 3770). 



The Apbil Meteors. — Moonlight will greatly interfere with 

 observations of the shower this year. The maximum will probably 

 occur on the morning of April 22, and the moon will be full on the 

 evening of the same day, so that only the brighter meteors will be 

 visible. In 1901, April 21, there was a moderately plentiful display, 

 and it will be advi-able to watcli for its return this year, though the 

 brightness of our satellite wUl rob the. event of its conspicuous 

 features. 



May Metbors. — The moon will have sufficiently waned on the 

 mornings of the first week in May to allow the Aquarida to be satis- 

 faetorilv seen. This shower presents an orbital resemblance with 

 llalley's comet, and has therefore acquired a special degree of interest. 

 The comet is expected to return to perihelion in 1910, May, and it 

 will be important to watch annually for its associated meteor shower 

 during ensuing years to ascertain whether it intensifies as the earth 

 passes nearer to that section close to the parent comet. The mean 

 position of the radiant is at 336'4° — 2 5°, and this point does not 

 rise m England until shortly before 2 a.m., when morning twilight is 

 strongly in evidence in the north-eastern sky. In southern latitudes 

 the shower can be more successfully observed than in England, as the 

 radiant is visible for a longer period before sunrise. The meteors 

 are swift with streaks, and their paths are abnormally long, a leature 

 which seems characteristic of meteors directed from radiants at low 

 altitudes. 



FiEEBAi-i. OP 1902, Janxjabt 7. — At 8.30 p.m., a very brilliant 

 detonating fireball was seen by many observers in New South Wales. 

 At Sydney tlie object is described as having increased in size as it 

 travelled along, and as finally exploding in the same manner as a 

 rocket Some of the fragments travelled eastwards, and ■' appeared 

 to go down into the sea." At Scone the fireball passed from S.W. to 

 N.E., and two minutes afterwards a tremendous concussion shook 

 the doors and windows. A noise as of distant tliimder was also heard. 

 At Gunnedah the blaze of light startled pedestrians, while at 

 Newcastle the earth and sky are stated to have been brilliantly 

 illuminated for several seconds with a beautiful orange-coloured light. 

 Air. W. E. Besley, the Director of the Meteoric section of the 13. A. A., 

 has received about twenty accounts of the meteor, and though most of 

 them are of a very imperfect character he has aproximately deter- 

 mined the real path. The beginning height was 71 miles, over a pmnt 

 20 miles E.of Muswellbrook, andtheobject moved to N., disappearing 

 when 28 miles over 20 miles W. of Walcha. Radiant at about 

 240° — 83° in Octans, but the exact position is doubtful. 



Laboe Meteors. — The following have been reported from various 

 places, and it would be useful to have further descriptions : — 



1902, January 24, 5h. 25m. Like a large rocket. From N.W. it 

 moved slowly nearly parallel with the horizon towards N.E. Altitude 

 45 ', duration 5 to 8 seconds. H. Sheppard, Bergen, near Bishop's 

 Stortford. 



)9ii2, January 24, 12h. Im. Biiuht meteor passed from a little E. 



of a Lconis, towards S. of W., crossing the moon in its flight. 

 Duration 5 seconds, streak lasted 10 minutes. P. Mulligm, Lancaster. 



1902, January 30. 6h. 25m. Mag. 1. Falh 4U° + 20° to 4.5° + 9°. 

 Slow. Reddi.sh-yellow train. Ivo F. II. C. Gregg, liouriiemouth. 



1902, February 1, 8h. 20iii. Brilliant meteor fell Ui the ea.«tward. 

 It was of a steely-blue colour and descended with an inclination 

 towards N., bursting into fragments in its passage through the 

 atmosphere. Or. Tavlor, Shrubland PHrk. 



1902, February 1, 12h. 4m Equal to Capella. Travelled from 

 near the zenith to N.W. and disappeared in Cassiopeia. Wery rapid. 

 Ten minutes later an electric-blue meteor, twice as bright as any star 

 visible, appeared in the zenith and passed due N., disappearing at the 

 Pole star. G. II. Price, London, S.W. 



1902, February 12, llh. 14m. Brighter than Venus. Path 

 215° + 35° to 195° -H 20°. Verv swift left a streak forscveral seconds. 

 Eev. W. F. A. Ellison, Dublin. 



1902, February 15, 8h. 25m. Bright meteor shot from direction of 

 Orion and travelled towards west. Duration, 4 seconds. Colour, 

 head blue, tail consisted of three red balls. F. F. Grench, Wimbledon. 



1902, March 5, lOh. 35m. Meteor equal to Capella shot from 

 158" + 70° to 98° -I- 40°. Duration of flight 2 to 24 seconds. Eev. 

 W. F. A. Ellison, Dublm. 



1902, March 6, lOh. 58^m. Mag. 1 to equal Sirius. Path 

 108° + 29° to 110° — 2°. The meteor gradually brightened during the 

 second half of its path, and then suddenly vanished. The nucleus 

 was bluish white, witli a train of yellow sparks. C. L. Brook, 

 Meltham, Huddersfield. 



THE FACE OF THE SKY FOR APRIL. 



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



The Sun. — On tlie 1st the sun rises at 5.40 a.m., and 

 sets at 6.30 p.m. Ou the 30th he rises at 4.38 a.m., and 

 sets at 7.18 p.m. 



Few sunspots are to be expected. 



A partial eclipse of the sun takes place on the 8th, but 

 it is visible only in the high latitudes of the North 

 Pacific Ocean. 



On the 22nd the moon rises at 7.5 p.m. totally eclipsed ; 

 the times of the various phases of the eclipse are as 

 follows, whilst the phase at any particular instant may be 

 deduced from the diagram below : — 



h. m. 

 First Contact with Shadow 5 0-2 



Beginninc^ of Totality ... 6 102 



End of Totality 7 35 4 



Last Contact with Shadow 8 45'4 



Last Contact with Penumbra 9 55 3 



G.M.T. 



Diagram s owing the path of the Moou through the Earth's Shadow 

 and the phase at 8 P.M., April 22ud. 



