182 



KNOWLEDGE ♦ 



[Feb. 27, 1885. 



identical in principle witli tlie "tisli" nippers described on p. 117- 

 The latter, however, act by opening:, while JI. F. W.'s appear to do 

 so by closing. The latter cost a shilling. The former so small a 

 fraction of a penny that they are given away. — CnAs. Rose. Marked 

 for insertion, the purely theological portion being excised. — C. C. 

 D.wis. Your tracing is, per sc, valueless, because everthing depends 

 upon the aspect of the window. Dialling is a matter of spherical 

 trigonometry, and all I can say here is that the edge of the gnomon 

 must, in every case, be parallel to the axis of the earth. Go to 

 some second-hand bookseller's, and get sucli a book as Ferguson's 

 "Dialling," Leybourn's "Dialling Improved," by Wilson, &c. — 

 Leipsic. Nothing surpasses Chauvenet's " Spherical and Practic.il 

 Astronomy," published by Lippincott & Co., of Southampton-street, 

 London. For details of the aspect of the sky, consult Webbe's 

 " Celestial Objects for Common Telescopes." Star Charts in the 

 "New Star Atlas" by the conductor of this journal. Celestial 

 globes of Newton, Wyld, Stanford, or any geographical establish- 

 ment. — G. P. M.iCK. Certainly man can exist at a temperature of 



degi'ees. I cannot, without an amount of searching for which 



1 have no time, tell you the lowest temperature experienced 

 by Captain Nares ; but Gorochow noted —81° (i.e., 81^ below 

 zero!) at Werchojansk, on Dec. 30, 1871; this is only in 07^' 20' 

 north latitude. — P. h. W. Newcomb's. — UnX'LE John. No proof 

 exists "that this planet is in ,a semi-fluid state;" at any rate, 

 the crust is so thick that the entire globe behaves as a solid. Were 

 it otherwise, the thin, solid shell would slip round the Huid internal 

 spheroid, and the phenomenon of the precession of the equinoxes 

 would not exist. No; it is absolutely imiios.-iihh' "that the 

 planet has a rotation from north to south of a few inches a 

 year!" I have not heard of "the rapid movement of the 

 fixed stars " to which you refer. — E. A. Tixdall. My good 

 sir ! do not imagine that I resent the expression of any 

 reader's opinion (be he a subscriber or not) upon a question on 

 which he is competent to give it. I merely entered a mild protest 

 against yom- quasi-Papal fashion of teaching me how to edit this 

 paper. — A. J. W. The explanation of the telescopic disc of a star 

 involves some pretty abstruse mathematics, the phenomenon being 

 dependent upon the very nature of light itself. In fact, the larger 

 the aperture of the telescope the smaller that disc is. It is the 

 quantity of light we receive from a star which determines its 

 "magnitude." All fixed stars are, in reality, absolute points. A 

 planet is a totally different thing. It is sutficiently near for ns to 

 see its real surface. Here is a simple experiment for you. Foctis 

 your telescope, with its full aperture, on Jupiter. Now, by the aid 

 of a blackened card diaphragm, cut, down the diameter of your 

 object-glass to IJ inch, and again look at the planet. Its size will 

 remain the same ; albeit it will look very much dimmer. Repeat 

 this with a star, and you will find that the cutting down your 

 telescopic aperture will notably increase the size of the spurious 

 disc. — T. Ckawford. Thanks for the trouble you have taken ; 

 but the length to which the extracts run render them quite 

 inadmissible. The divining rod (or " finding -stick" of the 

 West of England) is a very old superstition. For a rational 

 explanation of its action read Carpenter's " Mental Physiology." 

 — R. T. Palmer. No; the question was never answered. 

 Can any one inform our correspondent how glass-tnVie pens are 

 made ? — II. Pillev. Chambers' " Mathematical Tables," published 

 by W. & K. Chambers, London, will cert.ainly suit you. Price not 

 given, as this is not an advertisement column ; but it is a cheap 

 book, under four shillings. — J. H. D. points out, justifiably enough, 

 the " fanciful absurdity " of supposing that " height and depth " in 

 Ephesians iii., 18 v., represent separate dimensions, as alleged by 

 " E. L. G.," in letter 1588, p. 137. — L.^titude. As good and cheap 

 a book as you can obtain is Young's " Navigation and Nautical 

 Astronomy," published by Crosby, Lockwood, & Co. in " Weale's 

 Series." There is a volume of tables in the same series for use 

 with it, wliich I have some idea you may get, bound up with it. 

 At .any rate it is purchasable separately. — Antony Gliins. I am 

 ignorant where the fire-extinguishing grenade is procurable — J. W. 

 Manxino. No mi6take whatever; 5i feet represent the /ocus of 

 the object-glass, not its aperture. To an eye, 5^ feet on the other 

 side of the focal image formed by such an objective Jupiter, or any 

 other object, would appear of the same size as he does to the naked 

 eye. As, however, we approach this imago we obviously begin to 

 magnify it. — A. E. R. I know of no such tables ; but, of course, an 

 ordinary proportion sum will enable you to find what you want ; 1 lb. 

 of coal will raise 11,000 lb. of water 1 degree, whether such water 

 be at a temperature of 35 or 7'J. — A. J. Gaskin. 1. The fault is 

 not due to the formation of "an electric film," but to the fact that 

 the current is not strong enough to properly govern both sets of 

 electro-magnets simultaneously. Probably your lower lamp offers 

 less resistance than the upper one. Measure the resistances if 

 you can. By increasing current, or joining the lamps in 

 series instead of parallel circuit (providing you can get 



the necessary EMF), you will jirobably be able to over- 

 come the difficulty. In the latter case, however, you wculd 

 require short-circuiting plugs or switches. 2. The impression 

 of the steps, &c., probably had its origin in their radiating heat 

 at a slightly different rate to the surrounding water, and so modi- 

 fying its crystallisation. The subject, though, is obscure. — E. C.R. 

 Your " extra luminous patches" on the sun were nothing in the 

 world but/(ic»/a, which were first observed by Galileo some 274 

 years ago. See Knowledge, Vol. IV., p. 179. — H. C. Wellington. 

 No books or pamphlets have, so far as I am aware, been published 

 on the new method of reckoning time ; although a mass of corre- 

 spondence on the subject has appeared in divers journals. — J. 

 Hekbert. While quite agreeing with you as to the desirability of 

 the adoption of the new time, 1 greatly fear that the chances of 

 its being so adopted are rather remote. I have it on good autho- 

 rity, that a strong opinion against changing the existing mode of 

 reckoning was expressed at the recent meeting of the Royal 

 Astronomical Society ; and if astronomers, as a body, set 

 their faces against it, the chances of its ever coming 

 into popular use are very small. The " Nautical Almanacs," 

 moreover, so far iJublished {i.e., up to 1888), adhere to the old 

 form of reckoning. For this reason I think it improbable that 

 " F.K.A.S." would be disposed to make any change in his " Face of 

 the Sky " until the (question is more definitely decided. — Waltek 

 MoODIE. The Dramatic lievieir is published at 12, Catherine-street, 

 Strand, London. Price not given for a reason repeatedly stated. 

 M.D. (Glasgow). For reply to your first qnery see Knowledge, 

 Vol. v., p. 351. In answer to your second, the time kept at the 

 railway stations, post office, &c., is Greenwich time, and the pheno- 

 mena of Jupiter's satellites, of course, will occur at the times given. 

 But Gla.-'joie time, i.e., the time obtained by the tr.ansit of the sun 

 or a star over the meridian of Glasgow, is 17 niin. 11 sec. before 

 that at Greenwich. For example, Greenwich mean midnight would 

 be only llh. -12min. 49Bec. p.m. at Glasgow by local time. — W. II. G. 

 kindly sends us the information that a course of six lectures is 

 now being delivered at Derby under the auspices of the Gilchrist 

 Educational Trust. The lectures take place every Wednesday 

 fortnight. They began on Jan. 21, and will terminate on Marc!) 

 25. Our obliging correspondent omits to mention the subject. — 

 CVMRO. The pole of the heavens is simply that point in space U> 

 which the extremity of the earth's axis points. Hence, if that axi.s 

 have a conical motion the celestial pole will describe a circle in the 

 sky, which, as a matter of fact it does. In the time of Hipparchus 

 our present Pole star was 12° from the Pole; 215 years hence it 

 will be less than 30' from it. After some 12,000 years or so Vega 

 will be the Pole star, and so on. Of course as the Equator is 

 always 90° from the Pole it will have a corresponding motion, 

 which gives rise to the Precession of the Equinoxes. — H. Trieman 

 Wood. Received with thanks.— The President of the Society 

 OF Architects. Received with thanks. — Borderer. I am 

 tempted to think that if springs "break" immediately upon 

 a gale of wind it must arise from the very great diminution 

 of atmospheric pressure which occurs at such a time. Thi- 

 subject of the actual temperature of the sun is one on which we 

 possess but few trustworthy data to guide us. On the whole 

 the most probable temperature of the solar surface is not foi- 

 from 18,000 deg. Fahrenheit. The most intense obtainable artificial 

 heat scarcely reaches 4,000. Nothing isknoYvn of the central heat of 

 the sun.— II. Brain. Where the ball is hit fairly in the middle, 

 the angle of reflection is equal to the angle of incidence ; where 

 "side" or "screw" is employed a ball may be made to do all 

 sorts of things. — T. Lvne Coode. I have nopamplets on cremation 

 whatever. Write to W. Eassie, Esq., 11, Argyll-street, London, W. 

 See paragraph in capital letters Yvith which the heading of the 

 correspondence column concludes. — Ja.mes Burn. Too purely theo- 

 logical for admission. — F. W. H. I am afraid that we are drifting 

 into mere logomachy. — Sir John Lubuock. Received with thanks. 

 — Lover of Knowledge asks for an explanation of the theory ot 

 ginger-beer plant; and further, whether after fermentation it is 

 intoxicating in any degree, and Yvhat effect it has on the human 

 system as an article of food ? — Anthropological Institcte and 

 Park.es Museum. Received with thanks.— An Earnest Thinker. 

 Indeed I am not ungrateful for the real courtesy and kindness 

 which can alone have prompted your gift of " The Blessed Hope" ; 

 but I can only repeat the words of the Scottish idiot on returning 

 the dictionary which some one had lent him: "I've read it u 

 through ; but eh ! it's a vair disconnectit bulk ! " 



The Cutler's Company of Sheffield approved on Wednesday :> 

 scheme for holding an Industrial Exhibition illustrative of Sheffield 

 manufactures during the coming summer. The Duke of Norfolk 

 has promised a handsome subscription, and over £1,000 has been 

 contributed to a guarantee fund. 



