286 



KNOWLEDGE. 



[December, 1903. 



following formnla; are given by The Scientific American for 

 the purpose : — 



1. Dissolve 5 to 10 parts gelatine in 100 parts water ; add 10 

 per cent, of a concentrated solution bichromate of potash, mix 

 thoroughly and keep in a dark place. When the articles joined 

 by this cement are exposed to sunlight for a short time, the 

 cement becomes tough and insoluble in water. 



2. Quicklime ... 4 parts. 



Litharge ... ... ... 6 „ 



Linseed oil varnish ... ... 1 part. 



A yen- Calaloi/iie. — 3Ir. C. Baker, of ■_'44, High Holborn, is 

 now issuing a fresh edition of his Catalogue of Microscopes, for 

 the year 1904. This list contains much valuable information, 

 and describes instruments and accessories for every description 

 of microscopical investigation. Reference to it indicates the 

 fact that, by special arrangement, Powell & Lealand's well-known 

 microscopes are now supplied by C. Baker. Also among other 

 new items will be found an illustration and description of 

 Dr. Spitta's Monochromatic Light Apparatus, which was 

 described in these columns at the time of its exhibition at the 

 Roj'eI Microscopical Society. The excellent arrangements made 

 in connection with the Slide-Lending Department are fully 

 detailed, and altogether the Catalogue is one that every 

 microscopist, who wishes to be conversant with the latest in- 

 struments and accessories for his work, must have among his 

 reference books. 



NOTES AND QUERIES. 



lier. J/. C. H. Bird. — Either of the followingbooks will meet 

 your requirements : — ■" A Popular Hand Book to the Micro- 

 scope," by Mr. Lewis Wright ; " Modern ^Microscopy," by Cross 

 and Cole ; and, as a complete text book, " The Microscope and 

 its Revelations " (Carpenter), edited bj- Dr. Dallinger. 



C. F. Hiiixun. — Amoeba are somewhat casual in their occur- 

 rence, and can frequently be found in non-running water and 

 on mud. No doubt your difficulty in collecting them is due to 

 your failure to distinguish them ; they are somewhat difficult 

 to recognise to those who are unfamiliar with them. The 

 method of mounting the Hydrozoa will be to wash well first in 

 fresh water ; then place in a shallow white dish or saucer, select 

 and cut off the portion that is to be mounted, and place it on a 

 slide slightly warmed ; drain away as much water as possible, 

 and add some glycerine jelly. Apply the cover-glass, allow the 

 slide to cool, remove the excess of jelly around the edge of the 

 cover, wash the slide in water, dry, and add several coats of 

 enamel or varnish. 



Communications and e>iquiries on Microscopical matters are 

 cordially invited, and should be addressed to F. Shii.lington 

 Scales, Knowledge Office. 326, High Holhorn. W.C. 



NOTES ON COMETS AND METEORS. 



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



Peeiodical Comets. — Of the seren periodical comets which were 

 expected to return to perihelion in 1903, only one (Brooks's comet of 

 1889 and 1896) appears to hare been re-observed This is a disap- 

 pointing result, but due to conditions which could not be overcome. 

 In 1904 several of the best-known comets of short period will return, 

 and the circumstances will be favourable in two eases. In tlie early 

 part of the year Pons-Winneeke's and D'Arrest's comets are due, 

 Tempel's ot 1873 should visibly return in June, while Encke's will 

 probably be weU observed in the autumn. The latter has returned 

 twenty-five times subsequently to its detection by Pons in 1819, and 

 it has been observed on every occasion. At intervals of thirty-three 

 years ( = 10 periods) this comet returns at nearly the same times of 

 the year as before, and traverses approximately the same path in the 

 sky ; thus in 19U4 the favourable returns of 1S05, 1838 and 1871 will 

 be repeated. Mechaiu was the first to discover this interesting comet, 

 and its mean periodic time derived from thirtv-five returns between 

 1786, January 30, and 1901, September 15, is = 1206 6 days. 



GiAC0BiNi*s Comet (1896 Y.).— This comet, which passed its peri- 

 helion last June, is possibly visible in large instruments, though its 

 rediscovery has not yet been announced. Its place is computed as 

 R.A. 3h. aum. 42s., Dec. + 3° 49', on December 7, and R.A. 3h. 17m. 

 22s., Dec. -i- 3° 48', on December 15. The object wdl therefore be 

 nearly stationary on the eastern border of the head of Cetus. 



Comet 1894 I. (Dbsxixg).— Dr. P. Gast has published in the 



ilitteilungea ot the Heidleberg Observatory a summary of the 

 observations and calculations relating to this comet, and gives the 

 positions, ascertained in 1902, of 88 comparison stars lying near its 

 track. The data collected will be valuable in the final determination 

 of the orbit. The comet should return under favourable conditions 

 in the winter following 1908. 



October Metboes. — Stormy weather and cloudy skies have 

 continued to prevail, so that few opportunities have been presented 

 for any kind of astronomical observation. Fortunately, however, the 

 nights from October 22-25 were generally clear at Bristol, and 74 

 meteors were observed during nine hours ot watching. Amongst 

 these were 14 !; Geminids (99" + 13°) and 10 Orionids (93° -H 16°). 

 The results are somewhat noteworthy as proving what the writer 

 observed in 1900 and 1901, that the ^ Geminids appear to have 

 supplanted the Orionids as the richest shower of the period. Among 

 the contemporary systems, the most active this vear were situated at 

 91° -H 59', 117° '+ 4«>° and 128° + 33° (swttt meteors), and at 

 29° -I- 36°, 32« -t- 19°, 40° -I- 21° (slow meteors). 



DotTBLT - OBSKEVEU Meteoe. — A fine meteor directed from a 

 radiant close to t Arietis, was observed by Mr. C. L. Brook, at 

 Meltham, near Huddersfield, and by the writer at Bristol, on October 

 23, lib. 47im. As seen from Meltham, the object crossed the 

 equator in Pisces, the apparent path being from 3*^ •*- 3° to 3t6°— 4°. 

 As viewed from Bristol, it shot through Draco and passed over 1 in 

 that constellation as it descended almost vertically in the X.X.W. 

 sky. The height of the meteor was 75 miles wbeu first seen over a 

 point near Knighton, Radnorshire, and 37 miles at disappearance over 

 the district of Llanfair, Montgomeryshire. Its length of path was 

 48 miles, and the earth point is indicated 10 miles S.W. of Denbigh. 

 The shower of Arietids, from which the meteor was directed, forms 

 one of the principal displays in October, and it is one which vields an 

 abundance of fireballs. At Bristol, in 1877, October 28 to Xovember 

 1, 31 meteors were recorded from a radiant at 43° •♦•22°, and in 1887, 

 October 11-24, 45 meteors were noted from a centre at 40° -H 20°. 



FlBEBALL. — On November 3rd, Gh 25m. p.m., Mr. C. Grover, ot 

 Lyme Regis, observed a large fireball suddenly light up the landscape 

 with a brilliancy equal to that of the full moon. A bright fragment, 

 of th; apparent size of Jupiter, detached itself from the principal 

 mass and descended vertically about two degrees west of A Aquilae. 

 The same fireball was seen by Mr. A. F. Parbury, ot Hascombe, 

 Surrey, in the S.W., and he describes it as a long train of fire, 

 vertical, and near the horizon. It was also witnessed by a corre- 

 spondent of the Standard signing himself " W. D. F.," who says that 

 as he was crossing the Purbeck Hills, Dorset, he saw a very briUiant 

 meteor in the S.W. It fell diagonally from left to right, and 

 disappeared at about 40 degrees above the horizon. " The shape 

 suggested an incandescent tadpole diving from the stars." This 

 fireball was situated over the English Channel, between Lands End 

 and Brest, on the west coast of France, but the observations are not 

 sufilciently exact to permit the real path to be calculated. 



Bhight Meteob. — A meteor rivalling Jupiter in brilliancy was 

 seen by Mr. H. Macpherson, junior, of Johnsburn, Midlothian, on 

 November 7, 7h. 10m. p m It passed from near Altair to near Alpha 

 Ophiuchi, emitting a blue light, and lasting only a few seconds. 



December Gbmikids. — The return of this annual shower should 

 be looked for on the nights December 11, 12, and 13. The moon will 

 be past the last quarter, risiug after midnight, and will offer little 

 impediment. The radiant point, like that of the Perseids, probably 

 has a motion eastwards, but sufficient observations have not yet been 

 obtained to render the fact certain. 



The Leo s ids of 1903. — The Leonid shower formed quite a 

 striking display as observed at Bristol during the morning hours of 

 November 16. The maximum appeirs to have occurred between 

 5h. 3(im. and 5h. 4.5m. a.m., when Leonids were falling at the rate 

 of about 170 per hour for one observer. Several fine meteors as 

 brilliant as Jupiter or Venus were seen, and the radiant formed an 

 area ot several degrees round the central point, 151" ■(- 22'. 



THE FACE OF THE SKY FOR DECEMBER. 



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



The Sun. — On the 1st the sun rises at 7.44 and sets 

 at 3.53 ; on the 31st he rises at 8.8 and sets at 3. .57. 

 Sunspots may now be observed at any time, for the sun 

 appears well on the way to the period of maximum activitv. 

 There have been of late rarely less than three groups of 

 spots on the solar disc. During these periods of remark- 

 able solar outbursts and magnetic disturbances, auroi-ae 

 should be looked for in the north. The sun enters the 



