JtLT 7, 1882.] 



♦ KNOV\^LEDGE ♦ 



gnslun-fl! to Corrrsponlifntfi!* 



*^* All commun\eation» for the Editor requiring early attention thould reach the 

 C^ce on or before the Saturday preceding the current isiue oj Knowlbdoe, th» 

 increaeing circulation of xhich compile ii$ to go to prett early in the tceek. 



HiKTS TO COBSISPOKBIICTS.— 1. Ab qnetfioni atlcing for icientijic in/ormation 

 can be anncered through the poet. 2. Letters tent to the Editor for correepondentt 

 cannot be forvarded ; nor can the namee or addreeeea qf correepondenta be gittn in 

 anencer to private inquiriee, 3. Correepondente ehould terite on one tide otily of 

 the paper, and put dratcinge en a eeparale teq/. 4. Each letter should hate a iiile, 

 and in replying to a letter, r^erence should be made to its number, the page on 

 which it appears, and its title, 



M. E. H. H. Your answer to " Pjranius" is not coirect. IIow do 

 you make out fourteen for tliird year ? There would be twelve for 

 lirst year, each of whom at end of year would pay £40, making, 

 with £6,000 annual subscription, £6,480 ; out of whicli, twelve more 

 would each receiTe £500. At the end of second year there would 

 bo £6,960 for distribution, and thirteen (not fourteen) more sub- 

 scribers would receive, each, £500, and so on. — il. J. Madge. As 

 stated, we were referring to the idea as presented by our corre- 

 spondent. Permit us to say that your way of putting the theory 

 is entirely unscientific — the " evolution of immense volumes of 

 electrical energy which, flj-ing ofi from the sun's body into space," 

 <ic., do such and such things, will really not do in the way of 

 scientific descrijjtion, even if the ideas underlying your account wero 

 sound. The theory that the greater eccentricity of cometic 

 orbits is duo to the cometic nucleus being "constituted of a 

 nature less amenable to electric absorption than the planets," 

 is utterly untenable. — F. Sk:.t..\k. Thanks ; will consider both 

 points. — EBi.N-GO-BRAcn. Centre of earth generally regarded 

 as solid. We are approaching Hercules, rale not known. 

 Estimate usually given (150 million miles per annum) 

 unite untrustworthy.— F. Wixgheld. The question, p. 4-1, should 

 liavo been, When wiJI Arcturus cross the meridian three hours before 

 noon 'f The mistake is tolerably obvious, for if sidereal time on 

 December 9 at noon is 17 h. 10 m., it wiU not be 14 h. 10 m. at 3 p.m., 

 but 20 h. 10 m. — J. Clakk wishes to know where in the writings of 

 Augustine the saying occurs : " God is great in great things, but 

 greatest in small things " (veiy kind of Augustine thus carefully to 

 apportion his praise). — One Offe.sded. Your complaint is pre- 

 posterous. Wo cannot ask advertisers to certify that the goods 

 they offer at specific prices are worth the money. " Yea, indeed," 

 as you put it, that would be absurd. — F. G. A. A bicycle in not 

 kept in the vertical position in the same way as a hoop. In the case 

 of a rolling hoop there cannot bo displacement from the vortical 

 without greater changes in the direction of motion of particles of 

 the hoop than the hoop's weight can produce. But in the case of 

 !i bicycle, oven when at Ugh speed, the weight of the rider would 

 .suffice to bring the instrument and himself over, did he not com- 

 bine with balancing movements such slight changes of direction as 

 cause the weight which had boon tending to produce sway in one 

 direction to act iii the opposite. The greater the rider's practice, 

 tho less these changes, till they are practically evanescent. But 

 no bicyclist could trust to the steadiness resulting from the mere 

 running of the wheels. — J. A. L. R. I doubt whether any photo- 

 graphs of tho recent solar eclipse will bo available for tho '" public 

 eye " for many months to come. Very little of importance was added 

 to oar knowledge of the sun on that occasion. All that about 

 evidence of tho dissociation of tho so-called elements in tho sun is 

 sheer windy nonsense. Professors Liveing and Dewar have dis- 

 proved tho supposed terrestrial evidence, and Professor Young 

 tho supposed solar evidence, and nothing new was obtained on 

 that point, last May. — PnAiiMACEi'TicAL CnEMUsT. Fear it is 

 only too true that bicycling injures tho spino, though strongly-built 

 men may not notice tho effect for a long time. Theoretically, 

 nothing could be much more mischievous to the system than jarring 

 tho body when in the attitude necessary for bicycling.— II. W. 

 .Mai.et. The lato Sir Charles I.yoll, on tho contrary, attached great 

 weight to Mr. CroU's geological investigations. Tho subject is, 

 however, as you say, very dillicult. 1 cannot quite see why I ho 

 mere fact that the undated carboniferous system has buried 

 the .Ti- miles of denuded matter, justifies your considering tho 

 work of denudation to have been done under water, and so mul- 

 tiplying tho time by 1,740! Again, tho goograiihiciil, and not the 

 physiographical (horrible word), is the true surface measure in such 

 oiscs; for tho average denudation per s(iuare mile is in question, 

 not tho avcr.ago measm'cd vertically to the surface, with all its 

 varying slopes. — A REAnKK ok Knowledge. The comet may pos- 

 sibly bo visible in tho positions indicated elsewhere ; but only with 

 ■ a good telescope. — Campsie. Fear tho transference of engmvings 

 to porcelaia rather outside our range, but if any readers of Know- 

 ledge know how such work is done, wo will find simce for their 

 .iccount, if not too long.— AfGU.sTfs J. Harvev. Ah, yes ! get 



Government to do anything, and it is sure to be done well, — 

 Cioverument not being carried on by men like the rest, but by men 

 officially etherialiscd. Your " one hundred national painters," all 

 painting " for the glory of England," would be sure to raise the tone 

 of art. Our school boards ought to adopt this as a copy-book text, — 

 Official Pcsition Ensures Continuous Aiuiduilij.— W.Vt'. I would like 

 to tell you at what point of tho celestial compass our globe is at 

 the summer solstice ; but — forgive my ignorance — what i« the celes- 

 tial compass ? — J. A. W. Oliveb. Thanks for your valuable and 

 suggestive letter. — Cabl S. The reverend gentlemen you quote 

 and name imagine that because they can only conceive a deity very 

 limited in his attributes (though they talk of Infinite Power, Om- 

 niscience, Omnipresence, and Eternity), science, which smiles at 

 their limited deity, is atheistic. They are quite honest, however, in 

 their denunciations. They have gravely told me of a scientific 

 club — president, Professor Tyndall — founded for tho advance- 

 ment of atheism. The object, no doubt, is to get rid of all 

 restraints, religions or moral. It is, of course, well known 

 that nine-tenths of all the offenders brought annually to judgment 

 in civilised communities are men of science (under disguised 

 names). — A. Aitke.v. Sorrj- for tho mistake about postage; but 

 the wrapper should have been sent to publishers, not to editor. I 

 do not think your solution of Pyraraus's question quite right, unless 

 we assume that, as fast as money comes in, it is used to give sub- 

 scribers their £500, or such part nf it as can be distributed, those 

 who have received a part paying a proportional part only of 

 the annual .£10. In that case, of course, your solution would bo 

 correct. Every one seems to understand the question differently, 

 by-the-way.— G. L. U.akbai'. If I remember rightly, there is 

 a good exposition of the Nebular llypothesis in Prof. Xewcomb's 

 "Popul.ir Astronomy." — II. A. B. (1) Arago's delightful Essay 

 on Lightning (in his "Meteorological Essays"). (2) The fact 

 that after June 21 tho days do not shorten as rapidly as 

 they lengthen after December 21 i.s due to the motion 

 of the earth being slower in Juno and July than in Decern 

 bcr and January. Tho ear<h, as it were, han^s longer in tho 

 solstitial neighbourhood. (3) The sun's orbit m stellar space is 

 not circuited in hundreds of thousands of years; thousands of 

 millions would be nearer the mark, I imagine. (4) The instinct 

 and reason differences hard to define. — R. S. McKebreli. Go 

 through the work to bo indexed, writing down the title and ]>ago of 

 each subject on a separate small sliji of pa])er, or, if of sufficient 

 importance, on two or more, varying the heading, as,— Spots i^n tbo 

 Sun, by W. Uupgins, p. 113; Sun, Spots on, W. Uuggins, p. 113; 

 Huggins, W., Spots on the Sun, p. 113. Ilieu sort ; first into 

 letters, then under each letter into proper alphabetical posi- 

 tion. — W. Lees. Wo have such a list ; but wo aro not 

 free to lend it ; so far as wo aro concerned, wo ivould 

 willingly do so. We do not belong to the society.— Serckast 

 A. SnARPE. Many thanks ; but electrical and telegraphic articles 

 already provided for. — Faheu.vt. That leaf (v., vi., in No. 33), is 

 not to be bound with the volume. The advertisement ytar. ni 

 foot of p. 47, was inserted by mistake of printers, as you can gntlicr 

 by glancing over ndvertiscuieut columns. The contributiir you 

 name has promised to do what those you refer to would not do, and 

 his papers will have an independent value accordingly, and bo 

 practically more useful; just as my valued friend F.R-A.S. 

 describes nothing in his " Nights " which ho has not oianiincd 

 at the telesco|» within o few hours of tho time of writing. 

 —J. U. ConUETT. Four weeks of ill-health (we aro quite well 

 again, thanks) must be onr excuse for not sooner replying. Liko 

 you, we have never soon oitlar A'cnns or Eve, in painting or statue, 

 represented otherwise than as a more or less be.iutiful young 

 wonuin, born in the usual way. Michael Angelo, who repn-sentod 

 Moses with horns, might Imvo venlurcjl on a bolder cours«' with 

 either of those ladies, or with both. Many thatiks for your kiml 

 advocacy.— J. L. 11. Thanks for solutions of mathematical 

 probl.-ms. Wo give shorter and more general solution.— J. Gbkv. 

 Doubtless the comet : see part of reply above to J. H. Cobbett.— 

 Excelsior. See reply to J. II. Cobbett.- A JiNioK. It shonld 

 hardlv bo necessary to say that I jwrsonnlly would prefer having 

 more" astronomy; but 1 yield place to others, and ask others 

 to do part, or must of the astronomy.— J. A. U. Tho diffi- 

 culty has lK>en that description of the microphone turni-d out to 

 lie very long and illustration rather exiKmsive. We cannot keep our 

 corrcspondenia' promises.— P. H. D. The ice theory li;»s .lilficullios ; 

 but if every year there is a cold spell due to ice, an.l the iiveraKO 

 lime for thVis a particular part of May, that would .account fi>r tho 

 observed fact— the thiTO cold days.— C. M. P.h.lk. Yea; t hero is 

 room fi.r oil. Tho point is that with natuml increase, even as now 

 checked in England, a few hundred years would overcrowd 

 the earth, counting "humans" only.— .1. K. Yes; Browning's 

 Rninbnnd Spectroscope shows the niin-sign admirably.— VkubI'si 

 Sap. Yesj but how nU>ut tho prcprielors, if we thus do advcr- 



