Aug. 14, 18i 



'•] 



♦ KNOWLEDGE ♦ 



way of saying that if the earth's absorbing atmo- 

 sphere were annihilated the sun's rays " would raise 

 one gramme of water three degrees centigrade per minute 

 for each normally - exposed square centimetre of its 

 surface " ; which, for the benefit of those hapjjily unfa- 

 miliar with South Kensington cram-books, may be trans- 

 lated 15-43 grains of water 5-4 deg. Fahr. per minute for 

 every 'SOSTl- inch of its exposed surface. If we are to 

 accept Professor Langley's theory of selective absorption 

 and carry it out to its legitimate conclusion, we shall 

 arrive at some jirct ty startling results. Among them that 

 Sir John Herschel was hopelessly in error as to the lunar 

 temperature ("Outlines of Astronomy," pp. 284-5), which, 

 so far, as he (loc. cit.) states, from "possibly .... exceed- 

 ing that of boiling water," mu.st — if Professor Langley's 

 views be correct — be considerably lower than —200 deg. 

 Cent., even under a vertical sun ! With which astonish- 

 ing statement we commend the careful peinisal of a really 

 remarkable work to every one interested in solar physics 

 and meteorology. 



The Asdepiad. By Benjn. "Ward Richardson, M.D. 

 July, 1885. (London : Longmans, Green, & Co.)— The 

 observation which we have made above in connection 

 with Mr. Trever's work, that it possesses a certain 

 interest outside of that profession to which it is 

 especially addretrcd, appilies «'' fortiori to Dr. Richard- 

 son's capital quarterly magazinr, iii:isiiuu-li ;is it ;il\vrtys 

 contains more or less matter :it ox't- riMilalili' by and 

 insti-uctive for the ordinary himii of ^liiiirr. In the 

 present number an article (ui '■ il(.iiirl'',s,i uiid X(.iii;Mlic 

 Populations: their Saiiitiiry Con. lit i.m and 1 ii^]:rrn(.u,'' 

 quite falls within this L-.dr'^nvv. 



Proceedings of the Am. ri'cxn PI: :i.,s>>i^l:i'.d S^^ri.f,,, 

 Parts L, II., and III., for 1883. (■j'lnladrli,!,!:, ; .MrCalla 

 &: Stavely.)— The first two parls nf tliL.s.' ■■ I'mcc.aiiigs" 

 contain a variety of scientific pai-ci-s cf tlic type usually 

 found in such publications, but the third pcssesses a 

 peculiar interest, it being made up of the Old iliuutes 

 of the Society from 1743 to 1838. The astronomer will 

 read with interest of the appointment and doings of the 

 Committee to Observe the Transit of Venus in 1769. 

 At the meeting on May 20, it was decided for " Ewing, 

 Williamson, and C. Thomson to wait on Miss Norris, to 

 request the use of her telescope." We wonder who 

 Miss Norris was, and whether her telescope has survived 

 her. Five heliotypes of the exterior and interior of the 

 Society's buildings, and a sixth, which is a facsimile of 

 a letter from Benjamin Franklin, are bound up in the 

 volume. 



Geometry and Oravitation. By Alfred Jukes Allen. 

 (London : Abraham. Kingdon & Co. 1885.) — All who 

 wish to see the operation of the law of gr.Tvitatinn 

 lucidly explained by geometrical methods slmuld L^if tlii 

 little book. The author incidentally slioxvs li.iu ii 

 follows from the doctrine of energj- that if the ncIikiiv 

 of a body describing an orbit about another at a giveu 

 distance from it is the same in different orbits, the 

 velocity at any other distance is also the same in all. 

 His terminol..i:y is of the latest. 



77 ( /[ /' 'iTial. (London : Society for Promoting 

 t'liii i; , !-c.) The Little Ones Own. (London: 



l)c III ,v ^ 1 all of well-executed coloured pictures, 



and ul tak.^ iuul .sketches adapted to the capacity of 

 our nursery population, each of the publications named 

 above must bo eagerly looked for by its juvenile clienttle. 

 The parent who wishes to gratify his tiny ones with a 

 jileasurc to be anticipated every month, but who is un- 

 decided which of these little magazines to choose, .should 

 buy both. They are cheap enough. 



THE FACE OF THE SKY. 



Feom Acgcst 14 TO August 28. 

 By "F.K.A.S." 



THE student will turn his telescope on the Sun whenever the sky 

 is clear, to look for spots and facuta;. The face of the night 

 sky is shown in Map A'lII. of "The Stars in their Seasons." 

 Minima of Algol will occur at llh. 38m. p.m. on the 17th, and 

 8h. 26m. p.m. on the 20th. Mercury is an evening star, but is 

 rapidly getting into an unfavourable position for the observer 

 towards the end of the next fortnight. Venus is an evening star, 

 too, and may be seen glittering over the western horizon after 

 sunset. The rest of the planets are, as we said a fortnight ago on 

 p. 97, invisible. The Moon enters her first quarter at 6h. l-lSm. 

 a.m. on the 16th, and is full at 7h. Sl'm. o'clock in the morning 

 of the 24th. Three occultatioos of fixed stars occur at convenient 

 hours during the succeeding fourteen days. The first happens on 

 the 20th, when the 6th mag. star B.A.C. 6,2S7 will disappear at 

 the Moon's dark limb at llh. 39m. p.m., at an angle from her vertex 

 of 165°, reappearing at her bright limb at 12h. 35m. at a vertical 

 angle of 272°. On the same night, eight minutes after midnight 

 B.A.C. 6,292, another 6th mag. star will disappear at the dark limb at 

 a vertical angle of 115°. It will have set ere it reappears again. 

 Lastly on the 21st p' Sagittarii, a star of the 4th magnitude, will 

 disappear at the dark limb 35 minutes after midnight, at an angle 

 of 157° from the vertex of the Moon. As in the preceding case, 

 however, its reappearance will be invisible. The Moon is in Virgo 

 all day to day, leaving Virgo for Libra at 12h. 30m. to-morrow 

 night. Forty-eight hours later, i.e., 30 minutes after midnight on 

 the 17th, she passes into the narrow northern strip ot Scorpio, 

 from which she emerges at 10b. 30m. the next morning (that of 

 the 18th) and enters Ophiuchus. She leaves Ophiuchns for Sagit- 

 tarius at 8 a.m. on the 20th. At llh. 30m. on the night of the 

 22nd she passes into Capricornus, and from Capricomus into 

 Aquarius at noon on the 23rd. At midnight on the 26th she enters 

 Pisces. She is still travelling through Pisces at midnight on the 

 2Sth. 



I violent character visited various parts of 

 the country last week. At Northampton, on Wednesday, a young 

 man named Soden was struck by lightning, his sight being injured. 

 The West Berks district was visited on Friday by several terrific 

 thunderstorms. The first occurred at about two o'clock in the 

 morning, when the flashes of lightning were frequent and vivid, 

 and the peals of thunder particularly loud. A second storm com- 

 menced shortly before midday, but the most serious storm broke 

 over the district in the afternoon, when there was a heavy fall of 

 hail, lasting some time, and doing considerable damage to the com 

 crops on several farms. A great quantity of rain fell, flooding many 

 places. A heavy thunderstorm prevailed in the district of Ayles- 

 bury on Thursday night and Friday, accompanied by torrents of 

 rain. In Hartwell Park, nineteen shee]) belonging to Mr. Lee, which 

 had taken refuge under a tree, were struck by lightning. Sixteen 

 were killed on the spot, and the other three were so injured that 

 they had to be slaughtered. A fire-ball, it is said, fell on Hartwell 

 Vicarage lawn during a flash of exceptional rividness and a terrific 

 thunderclap. In other parts of the district injury has been done. 

 Some farm premises at Tring were struck. Birmingham was visited 

 by a heavy thunderstorm, accompanied by drenching showers. The 

 thunderclaps were exceedingly loud, and the lightning flashes very 



The 



n Mowl 



• thunder- 



