loS 



NA TURE 



[November 26, 1908 



OVR ASTRONOMICAL COLUMN. 

 Astronomical Occurrences in December : — 

 Dec. 2. 2h. Ilm. Saturn in cunjunclion with the Moon 

 (Saturn 2° 56' N.). 

 7. 9h. 55m. Middle of penumbial eclipse of the Moon 



visible at Greenwich. 

 „ ilh. 32m. OccuUation by the moon of 105 Tauri 



(mag. 5'8), reappearance I2h. 43m. 

 ,, I7h. 36m. Occiiltalion by the Moon of r) Tauri (5'2), 



reappearance i8h. 21m. 

 S. loh. 58m. Occultation by the Moon of i Gemino- 



rum (4'3), reappearance I2h. I3in. 

 9. igh. 2m. Neptune in conjunction with the Moon 

 (Neptune 2° 38' S.). 



13. I4h. 37m. Qjcullation by ihe Moon of / Leonis 



(57), leappearance ijh. 44m. 



14. loh. 47m. Jupiter in conjunction with the Moon 



(Jupiter 4° 22' S. ). 

 17. I7h. 50m. Occultation by the Moon of So Vir- 

 ginis(i;'8), reappearance i8n. 53m. 



19. I3h. 56m. Mars in conjunctun with the Moon 



(Mars 2= 58' S.). 



20. I2h. 3701. Venus in conjunction with the Moon 



(Venus o' 56' S. ). 

 22. 23h. 49m. Eclipse of the Sun. Invisible at (jreen- 

 wich. 



24. oh. 39m. Uranus in conjunction with the Moon 



(Uranus 1° 25' N.). 



25. Comet .Morehouse (19081) in perihelion. 



29. 8h. 14m. Satuin in conjunction with the Moon 

 (Saturn 3° 4' N.). 



MoKiiiiousE's Comet, 19081:. — Its declination having be- 

 come southerly on November 22, and its R..\. being within 

 2| hours of that of the sun, comet .Morehouse is now 

 becoming a more dillicult object to find, and this condition 

 has been considerably aggravated, in town, during the 

 past fortnight, by the haziness of the sky between sunset 

 and midnight. The comet now sets below the horizon 

 of London at about S. 15 p.m. 



A continuation of Dr. EbcU's cphemeris, prepared by 

 Dr. Smart, appears in No. 402 of the Ohservatory (p. 422, 

 November), and shows that, after its perihelion passage, 

 the comet will never rise above our horizon from about 

 the middle of January until the middle of May, 1909. 



The greatest southerly declination. So", will be attained 

 about >Iarch 24, and during its period of visibility the 

 comet will have practically travelled from pole to pole. 

 .'\ccording to the ephemeris, its apparent brightness is 

 now decreasing slowly, but wnII not fall below that at the 

 time of discovery until the end of .April. 



A second set of elements and a new ephemeris have 

 been prepared by Messrs. Einarsson and Meyer, of the 

 Berkeley .Vstronomical Department, and are published in 

 No. 139 of the Lick Observatory Bulletins ; the cphemeris 

 •extends to December 28-5. 



Halley s Comet. — A search-ephemeris for Halley's 

 comet, published in Popular Astronomy, gives the position 

 for November 27 as 6h. 21m. i8s., +11° 15' 17", and shows 

 that the R..\. is at present decreasing at the rate of about 

 44s. per day, whilst the declination is decreasing by about 

 30" per day. On November 27 the calculated distance of 

 the comet from the earth will be about 5-26 astronomical 

 units. 



According to Mr. Wendell, the radiant point of the 

 meteors from Halley's comet is R..\. = 22h. 43m., 

 dec. = + 1° iS', and it is suggested (the Observatory, No. 

 402) that meteors should be looked for from this radiant 

 about May 12 during the next three vears. 



In anticination of the return of Halley's comet and the 

 increase of our knowledge of comets that is likely to 

 result therefrom, the Astronomical and .\strophysical 

 Society of .-Xmerica has appointed a committee to organise 

 the proposed observations, so that the most useful results 

 may be obtained. 



A Snipi.F. Instrument for finding the Correct Time. 

 — In the November number of the Bulletin de la Socifte 

 astroiwminuc de France (p. 483I Prof. S. de Glasenapp 

 gives an illustrated description of a very simple apparatus 



NO. 2039, VOL. 79] 



by which the true time may be determined with wonderful 

 precision. 



The device is called the ccrcic solairc, and consists 

 of a metallic cylinder, about 4 inches in diameter and 

 half an inch in height, so suspended that a diameter 

 always hangs vertically, and so that its direction in 

 azimuth may be fixed. A conical hole is drilled through 

 one wall of the cylinder at a point 45° from the top, the 

 smaller end of the hole being directed towards the centre. 



The method employed is really that of equal altitudes 

 before and after the meridian passage, and the sunlight 

 passing through the conical hole forms a " disc " image 

 on an arbitrary scale marked on the interior wall of the 

 cylinder. To find the error of a watch, the times at which 

 the solar image transits, or is tangent to, or sym- 

 metrical with, the same scale marks before and after mid- 

 day are noted, and by a suitable reduction of the 

 observations the time, by the watch, of actual solar noon 

 is found. Applying the corrections for the equation of 

 time and the difference of longitude, if any, the actual 

 mean time is obtained. 



The instrument has been rigidly tested at the St. Peters- 

 burg Observatory, and the results show th.at the true 

 time may be obtained within forty seconds even when the 

 change of the sun's declination is neglected; if the latter 

 be taken into account, the reduction necessarily becomes 

 a little more complicated, but results correct within one 

 second may be obtained. 



Ephemeris for Jupiter's Eighth Satellite. — A new set 

 of elements and an ephemeris for the eighth satellite of 

 Jupiter, calculated at the Berkeley Astronomical Depart- 

 ment, appear in No. 140 of the Lick Observatory Bulletins. 

 The ephemeris gives the distances, in R..^. and declina- 

 tion, between the satellite and Jupiter until December 2. 

 The period of the satellite, according to the new elements, 

 is 2.2948 years. 



Designations of recently discovered Variable Stars. 

 — No. 427S of the Astronomische Nachrichlen contains the 

 final designations of fifty-three variable stars discovered 

 during 1007, as fixed by the Commission for the A.G. Cata- 

 logue of 'S'ariable Stars. The table also contains the 

 provisional number, the position (1000), the precession 

 (iqoo), and the range of magnitude of each star, and is 

 followed by numerous notes dealing with the peculiarities 

 of many of the variables. 



The Enu.meration of Minor Planets. — The permanent 

 numbers for recently discovered minor planets (1907-8) arc 

 given by Prof. Bauschinger in No. 4278 of the Astrono- 

 mische Xachrichtcn. The increase, during the past few 

 years, of the number of these objects known is shown by 

 the fact that the permanent number for 1908 C.S. is 659. 



The Variation of Latitude. — In reducing the inter- 

 national latitude observations it is assumed that the 

 individual variations, in a definite interval of time, are 

 equal, whatever star pairs be used, and in order to test 

 the validity of this assumption Mr. Hirayama has 

 examined the results of the observations for the period 

 iqoo-4. The results of his research appear in No. 4281 

 of the Astronomische Nachrichten (p. 133, November 7), 

 and show that the variation of latitude deduced from each 

 individual pair deviates more or less in a systematic 

 manner. It is also shown that the amplitude of the z 

 variation depends to some extent upon the zenith distance, 

 the brightness, and the difference in right-ascension of the 

 pair of stars observed. 



THE FOREST REGION OF MOUNT KENIA. 

 T^ENT.A is the only snowy mountain in the Old World 

 ■*■*■ lying exactly on the equator. Its height is 17,150 

 feet ; it has fifteen glaciers, and the snow-line is there 

 somewhat lower than to the north and south, where there 

 is more variation of season. Kenia is the culminating 

 point of the richest part of British East .Africa. The Kenia 

 snows can now be reached in little more than a month 

 from England by way of Mombasa and the Uganda Rail- 

 way. Mr. E. Hutchins (chief conservator of forests) and 

 Mr. Ross (director of public works in British East Africa) 

 recently returned from a tour round the Kenia forest and 

 a visit to the glaciers. 



