220 



♦ KNOWLEDGE ♦ 



[May 1, 1886. 



Rudiments of Chemist r>/. By Temple Or)ie. (London : 

 Swan Sonnenschein, Le Bas, & Lowrey. 188G.) — This little 

 book consists in effect of the description of a series of easy 

 and attractive experiments, l)y the aid of which the rudi- 

 mentary principles of cliemistry may be explained and 

 illustrated with facility. It is absolutely elementary, all 

 use of the atomic theory being eschewed, and the con- 

 sequent familiar equations being wholly absent from its 

 pages. A large proportion of the experiments described 

 may well be performed by any intelligent boy himself, and, 

 apart fi-om its undoubted use and value as a school manual, 

 we cannot help thinking that it would form a very welcome 

 and amusing present to any such lad with tlie slightest taste 

 for scientific pursuits. 



Mind your Ei/es ! Advice to the sliort-sighted, by their 

 fellow-sufferer, Francisque Sakcey. Translated by R. E. 

 Di-DGEON, M.D. (London : Bailliere, Tindall, & Cox, 18SG.) 

 — To everyone suffei'ing from short sight we would say, buy 

 and read Al. Sai'cey's amusing brochure straightway. When 

 we add, though, that it tells how he himself absolutely lost 

 the sight of one eye, and had to submit to the operation for 

 the removal of a cataract in the otlier, it may appear, to say 

 the least, odd, that it can be possible to apply the term 

 " amusing " to such a nai-ration. Nevertheless we repeat it 

 in connection with a piece of personal history, wr'itteu with 

 all the brilliancy of one of the most accomplished of French 

 litterateurs, and also repeat our recommendation to all 

 myopes to learn from its pages a lesson which may be of 

 priceless value to them. 



THE FACE OF THE SKY FOR MAY. 



By F.K.A.S. 



[In tlie preliminary note to this column, on p. 190, we recommended 

 the reader of our notes to provide himself with "Tlie Stars in 

 their Seasons." We would furtlier advise him to procure "The 

 Seasons Pictured," also by the conductor of Knowledge, as he 

 will find the zodiacal maps in it particularly useful in tracing 

 the paths of the planets. The large scale on whicli they are 

 drawn and the projection adopted render them \'cry suitable 

 for this purpose.] 



311E sun should be observed on every clear d.ay, as 

 tine spots and groups still appear at intervals on 

 liis surface. Map V. of " The Stars in their 

 Seasons" exhibits the aspect of the night sky. 

 After the 22nd twilight will persist all night long 

 throughout Great Britain. Mercury is a morning 

 star throughout the month. Ke ai tains liis greatest 

 elongation (26° 16') west of the sun at 1 A.M. on 

 tlie 7th. About tliis time he may be caught by 

 the nailed eje, twinkling over the E.ast horizon before sunrise. At 

 A.M. on the 31st he will be only 32' north of Neptune. Venus is 

 also a morning .star, and is, of course, much more brilliant and 

 conspicuous than Mercury. In the telescope she presents a crescent 

 akin to that of the moon in her last quarter. Mars now souths 

 soon, and must be looked at as soon as it is dark enough. He 

 is, though, a comparatively insignificant object, and requires a 

 powerful telescope to exhibit any detail on his surface. He 

 is becoming perceptibly gibbous (?'.<■., his periphery is less than 

 a circle). He is in Leo (zodiacal map, plate xxv., in " The 

 Seasons Pictured"). On the night of the 23rd he will only be some 

 3' south of the star x Leonis, shown in the map referred to. Jupiter 

 may be seen during the whole of the amateur's ordinary working night, 

 but should be looked at as soon as it gets dark enough. He is travel- 

 ling in the direction of /3 Virginis (zodiacal map, plate xxv., in "Tlie 

 Seasons Pictured "). The Satellites of Jupiter continue to present a 

 series of interesting phenomena to the observer. Beginning with 

 May I, Satellite I. will begin its transit 39 minutes after midnight. 

 On the 3rd the egress of the same satellite will happen at 91i. 22m. 

 P.M., followed by that of its shadow at lOh. 17m. On the 4th, 

 Satellite II. will reappear from eclipse at 12h. 28m. 48.s. p.m. On 



the 6th, Satellite III. will be occulted at Sih. 57m. P.M , reappearing 

 from occultation at Jupiter's opposite limb at 121i. 5ora. On the 

 9th, Satellite I. will be occulted at llh. 37m. P.M. On the 10th this 

 same satellite will begin its transit at 8h. o-jm., and be followed by 

 its shadow at 9h. 56m. The satellite will pass oif Jupiter's opposite 

 limb at llh. 11m., and the sliadow it casts at I2h. 12m. P.M. On 

 the lull. Satellite I. will reappear from eclipse at 9h. 18m. 58s. P.M., 

 and Satellite II. be occulted at lOh. 14m. On the 13th, the egress 

 of the shadow of Satellite II. will happen at 9h. 24in. P.M. On the 

 17th, at lOh. 37m. p.M , the same phenomenon will occur with the 

 shadow of Satellite III. Later, Satellite I. will enter on to Jupiter's 

 limb at lOh. 45m., as will its shadow at llh. 51m. The egress both 

 of satellite and shadow will not occur until the next morning. On 

 the 18th, Satellite I. will reappear from eclipse at llh. 13m. 30s., 

 and Satellite II. be occulted 41 minutes after midnight. On the 

 20th, the ingress of the .shadow of Satellite II. happens at 9h. 12m. 

 P.M. Thirty minutes later, the satellite casting it leaves Jupiter's 

 opposite limb, which the satellite itselE does not do until 

 llh. 58m. On the 24th, the egres? of Satellite II[. takes place at 

 9h 58m P M-, while Satellite III. itself actually does not enter on to 

 Jupiter's opposite limb until llh. 44m. Later, at 12h. 36m., 

 Satellite I. begins its transit. On the 25th, this same satellite will 

 be occulted at 9h. 44m. P.M. On the 26th, Satellite I. leaves the 

 planet's face at 9h. 20m. p.m., as does its shadow at lOh. 30m. On 

 the 27th, II. begins its transit at 9h. 21m., and is followed by its 

 shadow at llh. 47m, The egress of the satellite occurs at 12h. 10m. 

 P.M. On the 29th, Satellite II. will reappear from eclipse at 

 9h. 36ra. 53s. P.M. ; while finally, on the 31st, Satellite 111. will enter 

 on to Jupiter's face at lOh. 42ui. P M. Saturn is invisible, a remark 

 applying also to Neptune ; but Uranus may be found a little to the 

 s jutli and just to the east of the 3-4th mag. star )j Virginis (zodiacal 

 map, XXV., " The Seasons Pictured ''). The moon is new at 

 3h. 42ora. A.M. on May 4, enters her first quarter at 2h. 20'lm. A.M. 

 on the 11th, is full at lli. 47'lm. A.M. on the 18th, and enters her 

 last quarter at llh. 36-lm. p.m. on the 25th, Four occultations of 

 stars by the moon will occur at fairly convenient hours during May. 

 The first one happens on May 6, when the 5i mag. star 111 Tanri 

 will disappear at the moon's dark linili at 81i. 12m. P.M., at an angle 

 of 114° from her vertex, reappearing at her bright limb .at 9h. 3m. 

 P.M. at an angle of 324'^ from her vertex. At 9h. 42m. on the same 

 evening, 117 T.auri, a slar of the 6di magnitude will disappear 

 at the dark limb of the moon, at an angle of 88° from her vertex ; 

 but she will have set ere it reappears. On the 17th, t; Libiu^, a 

 6tli mag. star, will disappear at the dark limb at lOh. Kim. P.M. 

 at a vertical angle of 04'. It will reappear at the bright limb at 

 llh. 32m. P.M., at an angle of 240° from the moon's vertex. Lastly, 

 on the 21st, when the moon rises, she will have already occulted 

 d Sagittarii, a 5th mag. star at her bright limb. Later on, at 

 lOh. 67m. P.M., the star will reappear at her dark limb at an angle 

 from her vertex of 266°. In the description which follows of the 

 moon's path through the sky during May, the figures in parentheses 

 refer to the zodiacal maps in " The Seasons Pictured," and will 

 enable the student to trace her course in the heavens for himself. 

 When our notes begin, then the moon is in Pisces (xxii.), in 

 which constellation she remains until 3 A.M. on the 3rd, when .she 

 enters a corner of the most northerly part of Cetus. She takes 

 nearly 12 hours to cross this, and between two and three o'clock the 

 same afternoon passes into Aries (xxiii.). At 4 P.M., on the 4th, 

 she quits Aries for Taurus. She is travelling through Taurus until 

 6 A.M. on the 7th, %vhen she arrives on the boundary of the narrow 

 northern strip of Orion, which she quits in turn at 6 P.M. for 

 Gemini (xxiv.). Her passage through Gemini occupies lier until 

 9 A.M. on the 9th, when she enters Cancer. She remains in Cancer 

 until 9h. 30ra. P.M. on the 10th, when she crosses into Leo. It takes 

 her until 10 A.M. on the 13th to traverse Leo, and she then (xxv.) 

 passes into Virgo. She leaves Virgo for Libra at lOh. 30m. A.M. on 

 the lOtli (y:xvi.), and is travelling through Libra until 7 A M. on the 

 18th, at which hour she arrives at the edge of the narrow northern 

 strip of Scorpio. By 5 P.M. she has traversed this and passed into 

 Ophiuchus. At noon, on the 20th, she leaves Ophiuchus for 

 Sagittarius, as she does Sagittarius for Capricornus (xxi.) at mid- 

 night on the 22nd. Twenty-four hours later (( c. at midnight on 

 the 23rd) she crosses into Aquarius across which she is travelling 

 until 4 AM. on the 27th, when she returns to the constellation of 

 Pisces (xxii.), whence she set out. Continuing her course in the 

 sky, she, at 9 a.m. on the 30th, regains Aries (xxiii ). At mid- 

 night, on the 31st, she is on the confines of Aries and Taurus, where 

 we leave her. 



COMETS FABRY" AND BAPvNARD. 

 Fabry's comet is now travelling so rapidly down into the southern 

 hemisphere that it will soon be lost to sight in these regions. On the 

 night of May 1 it will be N.N.W. of the 6th mag. star { Eridani ; on 



