22 



KNOWLEDGE. 



[.Ianuart, 1903. 



G. L. — I am afraid that I am unable to advise j'ou in your 

 attempt to prepare realgar specimens, the work is frauglit with 

 80 much difficulty that it has been abandoned by ne;irly every- 

 one ; even those who do it professionally do not secure 

 uniformity, some specimens keep for a number of years, while 

 others decompose in a few days. 



Communications and enquiries on Microscopical matters are 

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

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



NOTES ON COMETS AND METEORS. 



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



Comet Pereixk (1902 b). — This interesting object is now necessarily 

 relegated to the care of observers in the Southern hemisphere, as its 

 position renders it invisible in high northern latitudes. Movingsome- 

 wbat rapidly in a 3.W. direction it has recently traversed Scorpio and 

 Centaurus. and will occupy a position in about 46 degrees south of 

 the celestial equator on January 22, thereafter returning north- 

 wards and again exhibiting itself above our English horizon early in 

 February. The comet approached comparatively near to the planet 

 Mercury on the morning of November 30 last, when the distance 

 separating the two bodies was equal to 1,644,000 miles. The following 

 is an ephemeris by Stromgrcn : — 



After the 6rst week in March the comet will finally disappear as an 

 object for ordinary telescopes. 



Comet Tempel-Swift. — No announcement appears to have been 

 yet received as to the rediscovery of this comet. The calculations 

 show that the present return to the perihelion has been much delayed 

 owing to the disturbing action of Jupiter. 



Comet Swift (1895 II.). — This comet was discovered by Lewis 

 Swift on Echo Mountain on August 20, 1895, and though a faint 

 object it was followed until February 5th, 1896, during which period 

 aliout 400 observations were obtained. M. Schulhof has recently 

 computed definitive elements, and remarks that " at the opposition of 

 1902 the comet will remain very faint; there may be hope, nevertbe- 

 lesi, that it may be found with the aid of some of the more powerful 

 instruments. There will be no possibility of observing it at its subse- 

 quent returns in 1910 and 1917. In 1924 its luminous intensity will 

 be almost the same as in 1902, but the limits of uncertainty in its 

 position will then be four times as great." 



JfoVEMBEB Leonids. — Once more the month of November has 

 come and gone without having furnished any striking meteoric 

 spectacle, and it is now certain that the present generation must 

 abandon all hope of witnessing a really grand exhibition of these 

 meteors. Our experiences in and since 1898 have been singularly 

 disappointing, and the (at least) temporary loss of the shower is to be 

 deplored on several grounds. Its recurrence would no doubt have 

 stimulated interest in the whole subject of meteors, while it would 

 certainly have proved an incentive to the more thorough observation 

 of these remarkable and numerous bodies. -■Vpart, however, from 

 special displays such as the Leonids occasionally produce it .should be 

 remembered that even on ordinary nights of the year the sky affords 

 a vast and continuous exhibition of meteoric phenomena which patient 

 and persevering observers may i-eadily witness and record with 

 pleasure to themselves and advantage to astronomy. 



FiEEBALLS.— November 3, Gh.— Mr. H. M. Cross, of Scarborough, 

 saw a very brilliant meteor shoot across the heavens from east to west, 

 leaving a long streak of light behind it. 



November 9, 7h. 20m.— Mr. Ivor F. H. C. Gregg, of Cambridge, 

 obseryed a fireball about two or three times brighter than Venus 

 moving very slowly, and leaying a fine streak. Path from 154° -h 57° 

 to 1324" + 54° ; duration of flight, 4 seconds. 



November 16, evening. — Very large meteor, with a trail of red 

 light, seen at Berlin. The meteor burst low down in the western skv, 

 and appeared like " a tremendous rocket." 



November 25, 7h. 45m. — A splendid meteor, noticed by a casual 

 observer at Bristol, moving rapidly in a north-west direction, and 

 throwing off a long train of sparks. 



December 2, 7h. 20m. — The Rev. S. J. Johnson, of Bridport, saw 

 a meteor brighter than Venus passii-g slowly near the stars k Draconis 

 — ^UrsiB Majoris. The meteor was greenish in colour, and it left a 

 train. Duration of flight, about 2^ seconds. The observed course 

 was from 187" -h 71° to 203°-r57 , and the probable radiant near cither 

 a Persei or £ Arietis. 



♦- 



THE FACE OF THE SKY FOR JANUARY. 



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



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

 sets at 3.-59 p.m. ; on tlie 31st he rises at 7.44 and 

 sets at 4.44. 



The earth is at its least distance from the sun at 1 a.m. 

 on the 4th ; the a]>parent diameter of the sun being then 

 at its maximum, 32' 35"-06; the horizontal parallax of the 

 sun is then 8"'95, also a maximum. 



Small groups of sunspots may be expected from time 

 to time. 



The Moon : — 



The moon is in perigee on the 13th, and in apogee on 

 the 25th. 



OccTJLTATiONs. — The principal oeeultations visible at 

 (jreenwich are as follows : — 



Ocoultation of a Cancri. 



The diagram shows the oecultation of the 4th magnitude 

 star a Cancri. The letters D and E indicate the points of 

 disappearance and reajipearauce. 



