238 



KNOWLEDGE. 



[October, 1903. 



Should any readers take up the study of these beautiful 

 creatures, dates of collecting, localities where discovered, and 

 particulars of anything they may have observed new in the life- 

 history, particularly varieties of colouring, should be carefully 

 kept, together with, if possible, drawings. There is one mite, 

 Fiona riii'd Korli, which has been found in England in three 

 distinct bright and beautiful colours, viz., red, green and brown. 



The two best text books on fresh -water mites are in German 

 — " Deutschlands Hydrachniden," by Dr. R. Piersig, rather an 

 expensive work, with about .'iDO pages of letterpress and 51 

 plates ; and a number of " Das Tierreich " on the IlydrachnidcF, 

 by Dr R. Piersig, Berlin, IHOl. This contains the account of 

 every known species up to date of publication. 



Lectuhks and Demonstrations in Microscopy. — One of 

 the rules of the Manchester Microscopical Society states that — ■ 

 " The objects of the section (Extension Section) shall be the 

 extension of the knowledge of Microscopy and Natural History 

 to outside associations by means of lectures and demonstrations." 



In pursuance of the objects set forth, this Society has pre- 

 pared a list of fifty-four lectures and demonstrations of various 

 microscopical subjects, some of which are illustrated by diagrams, 

 others by magic lantern, the microscope, or by actual specimens, 

 while in some instances two or more of these are combined. 



The work of lecturing and demonstrating is entirely gratuitous 

 on the part of the members, the only charge made being for the 

 hire of slides, travelling and out-of-pocket expenses, and in 

 gome cases an additional small fee for the lecture. This is 

 specially intended to present scientific knowledge in a jiopular 

 form before societies which are unable to pay large fees to 

 professional lecturers. 



This is a step which it is hoped will meet with great appre- 

 ciation, for it is undoubtedly in the right direction, and should 

 increase the popularity of the microscope. 



Full particulars may be obtained from Mr. Abel P. Bradshaw, 

 3, Clifton Street, Hulme Hall Lane, Miles Platting. 



Practical Scheme. — Through the kindness of a naval officer 

 in China, I am able to offer for distribution some spines of 

 EchinuK. 



The following is the manner in which he suggests they should 

 be ground and mounted : Slice the spine as finely as possible 

 with a fret-saw, dressing the cut end after each slice with a file ; 

 cement a number of slices to a slip by their smoothed sides, 

 with balsam, in the usual way. Rough them down with a 

 smooth file and a light hand, polish on a stone with water, turn 

 and finish on the other side with the stone, select the best 

 specimens, and mount in balsam. 



I shall be happy to send some of these spines to any readers 

 who will send a stamped addressed envelope, together with the 

 coupon which appears in the advertisement pages of this issue. 



NOTES AND QUERIES. 



A.R. — You will get your unmounted microscopic objects 

 from Mr. R. G. Mason, of tVJ, Clapham Park Road, S.W. He 

 has a large variety put up in packets, with full directions for 

 preparing. 



C. Moaliin. — It would appear that a mistake was made in your 

 lamp in the size of .slip. It is not unusual for lamp chimneys 

 to be provided with apertures of different sizes and shapes, so 

 that light may be only emitted from one definite spot, and the 

 room kept otherwise dark. You will probably have noticed in 

 the July number of this journal that Mr. Rousselet offers 

 suggestions as to the selection of objectives for Pond-Life, 

 which exactly accord with your ideas. 



C. J. S. — The only way to remove picric acid is to wash in 

 repeated changes of methylated spirit ; the specimens must not 

 go into water at all, and the staining should be carried out in 

 alcoholic solutions. Chromic and osmio acid solution sections 

 wash well in water, they should then be placed in a 10 per cent, 

 solution of bicarbonate of ^oda for about an hour, wash in water 

 thoroughly to remove all trace of soda, then place in methylated 

 spirit, which should be changed every day until water is 

 removed. Three changes are usually required. 



Communications and enquiries on Microscopical 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.b.a.s. 



Brooks's Pkhiodical Comet (1889 V.— 1890 VI.).— This comet 

 was first discovered on July 6, 1889, and kept well under obBervation 

 during tlie ensuing summer and autumn. At the end of the month 

 named it appears to have broken up into several distinct portions, for 

 it was thus observed at the opening of August. A period of 7'07 years 

 was found for the time of revolution, and it duly returned in ISyfi, on 

 which occasion it was first scon by M. JaveUc, of the Nice Observatory, 

 on June 20, and tlie comet passed its perihelion on November 4. 

 From the observations obtained, Herr Bauschinger redetermined the 

 period as 2592"i37 days, or 7'096 years. For the present return Mr. 

 F. E. Seagrave has computed an ephemeris, and finds that while the 

 comet made its nearest approacli to the earth at the middle of August, 

 the perihelion will not occur until December 1 1. Prof. Aitken, of the 

 Lick Observatory, redetccted the comet on August 18, and found it in 

 a position closely according with the ephemeris place. It is a faint 

 object, moving slowly eastwards low in the southern sky. The 

 following is an eplieuieris for Washington, midnight : — 



Distance iu 

 R.A. Dec. Millions of 



Date. H. M. 8. ° , Miles. 



October 4 ... 20 45 39 -24 32 129 



„ 8 ... 20 48 37 -24 131 



12 ... 20 52 4 -23 26 133 



„ 16 ... 20 55 59 -22 51 136 



„ 20 ... 21 18 -22 14 139 



„ 24 ... 21 5 2 -21 35 143 



„ 28 ... 21 10 9 -20 54 147 



ArorsT Meteors. — The moon was full on Augusts, and interfered 

 in no small degree with observations of the I'erseid shower. The 

 unfavourable weather of a very ungenial season added to the 

 dilficulties, and thus comparatively few meteors were observed. The 

 niglit of August 10 was, however, clear at Bristol, and the Perseids 

 returned, though by no means abundantly, shooting from the usu al 

 radiant about 2" N.N.E. of "n Persei The maximum evidently 

 occurred on the night of August 12, Perseids being very plentiful, 

 and falling from a radiant very sharply defined at 46" I- 58". On the 

 latter night, Prof. Hersehel, at Slough, saw about 25 meteors during 

 a three hours' watch, and found the chief radiants at 41° -f 58" and 

 49" -1-6 1", with indications of others in Camelopardus, while only two 

 meteors belonged to the minor showers of the epoch. 



Ddbation of the Perseid Shower. — A few swift meteors leaving 

 streaks continued to be observed this year until August 25, and as 

 they we. e conformable, both in aspect and direction of flight, with 

 true Perseids, it seems highly probable tliat the shower remains 

 visible until the date named. Observations in previous years have 

 also furnished distinct evidence of Perseids in the fourth week of 

 August. The radiant point on August 25 appears lo be in about 

 68° -1- 59°, but the position is not very precisely deflnej, the meteors 

 having nearly all appeared on the western side of the radiant. There 

 are showers of Camelopardids in August, from 60" -i- 59° and 77" + 57°, 

 the met»!or8 of which are likely to be confused with, and mistaken 

 for, true Perseids ; it is therefore impossible to conclude with certainty 

 that the great Perseid shower is visibly prolonged until August 25. 

 More materials are required, and to obtain these it will be important 

 to watch the northern sky between August 20 and 25 in future years, 

 and record with particular care the flights of any streak-leaving 

 meteors that may uppear. 



Brilliant Meteors. — On August 15, lOh. 44m., G.M.T., the 

 Rev. W. F. A. Ellison, of Enoiscorthy, observed a meteor equal to 

 Venus. It gave several briglit flashes and left a short train as it 

 moved from 20.5" -I- 54° to 182° -1-45°. On August 21, at 13h. 32m., a 

 fireball was seen by the writer at Bristol. It produced a flash 

 apparently as bright as the full moon, and left a streak of 5 degrees 

 1* to the right of 3 Cygni for about a minute. The path was from 

 295"-!- 30" to 285° -1-25 i°. 'Ibe radiant cannot be definitely assigned 

 as no other observations have come to bund. There was another fine 

 meteor seen at Kirkstall at an early hour on the same morning, for a 

 correspondent of the Yorkshire Daili/ I'ost alludes to it as shooting 

 from "a little above a Andromeda; to the well-known ' W ' of 

 Cassiopeia." On .\ugu8t 29, 8h. 15m., a pretty bright meteor was 

 noticed bv Mr. F. L. Raymond at Yeovil, in the west, travelling 

 rather swiftly from 210" + 35° to 190° -I- 20°. 



Real Path or a Meteor. — On August 25, 9h. 3.5m., Mr. C. L. 

 Brook, of Meltham, near Iluddersfield, observed a meteor of 3rd 

 magnitude i-booting from 347" + 2i° to 34l° — 8° in one second. The 

 same object was seen by ilie writer at Bristol, where the apparent 

 course was from 21° + 29° to 2U'' + 19°. It moved swiftly across 

 a Trianguli, and left a streak. The combined paths indicate a radiant 

 at 79" + 59°, and lieights of 70 to 52 miles over Suffolk and Essex. 

 This shower near 3 Camelopardi appears active in the months 

 August, September, and October. 



