128 



KNOWLEDGE ♦ 



[Dec. 9, 1881. 



9n^cr«( to CorirdpontirntsJ. 



*«*.!'/ commumcutioH* Jvr tkt EtUtor rrqttiring eartj/ tUifnlioit thould rtttck the 

 Offic9 on or h^ur€ tkn S^ttnrdfiy prtrfding tkr current isMUf of K^owlkdok, tkt 

 iNfr/iMiN'/ rircu/«i/tu(i oj trAici tomiirU tt» to qn to prtM ftrlj/ itt thr week. 



HlHTdTO CoRHKNl'ONDKSTJ*. 1. Xo qtteUion, iitkint fur Mrir„tijlc iu/ijrmalion 

 €am be artficfreti through tkr pott. 3. Letters ^r tit to the Editor for corrftpomimtM 

 cQHnot be fortrartird ,- nor ran the namet or addretaen qf correipondenta be giteit in 

 anerer to primte inqnirio. 3. Xo queries or rrplirt tacouring qf the mi'ttre qf 

 adcertieemeMtf cnn be imerled. 4. Letter/, gneriei, and repli*» are interled, ttitlrrt 

 roMlrarjf to IluU A, free nf rh.trge. 5. Corretpondfnls ehouLI vrite on OM aide 

 oitlg of the p'inrr, and put drmrhigt on <l nepurale leaf. (t. Enth letter, qiieri/, or 

 reptg ahouiJ haee <i tUte, and JM replying to leltere or queriet, r^erenee ehouid be 

 made to the number qf Utter or query ^ the pnge oh which it appears, and it$ title. 



K. II. R. The Witch of Agne^ i-i one of thone rurves jiivpntna in former times 

 for the solution of ceoniL-trical probloma which cannot bo HOlved by use of the 

 cin'lr und atrsiRht hno only. Wo find little about it in our books. Its equation 

 is given in Brnnde's '* Dictionary of Art and Scnenccs." We must study it u 

 little ourselves before answering your question ; und, nnxt week, hope to {p%r a 

 drawing of the cur^-«andabricf aromint of it : Reometriial, if possible.— Pi zzi.ed. 

 We do not wonder you are puzrled. The ^ttoteraent in the 'J'imea ift out of date 

 where it is correi't, and the rest of it aniUKingly inexact. Newspaper flrieuco is 

 apt to be "mixed" in this way.— O. O. Wakkkiklb. Your form of Holution 

 was specially deluded when the prize was offered. We have, however, 

 pivcn your solution as a jjood illustratiim of the way of writing down to any 

 required position, altcrinf;, however, your notation, which occupies too much 

 space. — W. W. WiLLMOTT. Your query appears, and number containing 

 it has been sent to author of the paragraph'.— h. C. R. Thanks for interestinf; 

 -W. A. S. Very K'ad i"^*<'c<l to "''"i" from vou. How lonfj it ' 



met. Your reply is a specially welcome one, for I feared that particular 

 query would remam unanswered. Roucht everywhere for information, but 

 knowing no Rabbis could pet none that was trustworthy.— Walter E. R. We 

 hope to have many papers on BioIo*ncal subjects ere long; but Science is 

 ialinite, and Knowleugo is not.— JoHX Blind. In your long letter you 

 urge the familiar objections to the sun's being the source of heat, and advance 

 a new theory of the tides. Of the former our readers have had a fair supply 

 already, and the latter is quite inconsistent with known facts. You are 

 alfto evidently unacquainted with the facts on which the accepted theories 

 are based. For instance, you say the sun exercises greater attractive 

 power than the moon, yet raises no double tide, the facts being (1) that 

 the Sim's tide-raising' power is less than the moon's in the proportion of 

 2 to 5, yet (2) that he does raise a double tide of proportionate height. We wish 

 vou and others who propound paradoxes, to understand that your objections are 

 in reality your difficulties. Those objections were difficulties "to science students 

 some two or three centuries ago. There is an unscientific objection to your com- 

 munication on the ground of po.stage underpaid. — J. McGbigor Allan. We 

 agree with much that you have written, but our pages are scarcely suited for the 

 physiological study of the subject. We agreed to a concise presentation of your 

 views, but supposed the column in Number 4 was what you meant ; or, that if 

 section 2 were treated at all, it would bo very briefly. The other sections will be 

 more suitable. Vray understand that we are satisfied no student of science could 

 by any pos^ibility object to your riewa or your way of putting them; but we 

 write not for students of science only — firginibue puerisqne caiUaniuf. — 

 Bkbtrjind K. Dawson. There is no real difficulty. Binders have repeatedly 

 to insert hulf-shectA. They will have to do so in the case of our star 

 maps. There is much less risk of the single page separating from its 

 fellows than of a full sheet coming out through imperfect sewing. — J, F. D. 

 Sbldst. It is impossible to insert your '* intentionally ambiguous" remarks on 

 the cause of gravity. Your replies to "Queries" 13 and 3 are unsatisfactory 

 from a similar ambiguity. Your fears eeem uncalled for. Publishing a new 

 and sound theory on any subject whatever, by no means involves, as a neceesary 

 oon^tequence, " utarvatioii, despair, and early death." Wasting many years over 

 a false theory, through unwise caution, may be more likely to lead to such unde- 

 siralde results. — .1. lIi?fEs. Your communication is too long for the subject, now 

 nea.ly ezhauHte<l (though the sun's tea' is not). The '* prevailing hypothesis of 

 the action of nndulatory forces" is by uo means inconsistent with the 

 heat of the sun being " true heat in the naked form," that is (as we under- 

 stand you) such heat as there is in a fire or furnace. Your theory is qiiite in- 

 consiNlent with facts ; and the growinfr pressure on our space, though it does not 

 forbid our weighing objections and considering doubts, w ill not allow of our devoting 

 columns tothe careful enunciation of untenable hypotheses. No paradoi-monger 

 who can honestly say {and eflfectively show) that he has thoroughly mastered 

 the accepted tlicorieH and the researches on which they rest, sliall be refused 

 ample space here. But paradoxes evidently based on misconceptions like those 

 of Mr. Newton Croslandand others can no longer have the space which we earlier 

 allowed them. They must make way for the sounder matter which reaches u«. — 

 U. M. Haasskn, You can scarcely form an idea of the pressure on our space. 

 Such a list as you suggest would be useful only to a small section of our 

 readers. Almost every one who attends such meetings knows when thev 

 arc to be held without our assistance.— John Spillbh. Thanks for your 

 letter, which shnll appear, unaltridged. It is very much to the purpose.— 

 ACTiNOHTK. Have mserted the gist of your query, but have omitted the 

 closing words. What has Knowledge to do with Professor RawUnson'a behef, 

 or want of belief, in Mosaic chronology? We know nothing about the 

 matter, to !)egin with; and we do not want to know.— Aldbbt E. Holpbn. 

 Thanks for your useful letter.— E. Kaycb. Thanks for your BUggestions. We 

 are proceeding tentatively at present, and, indeed, just now our unexpectedly 

 rapid success involves certain practical difficulties which will presently dis- 

 appear. The principles which will guide us in the choice of subjects will be 

 Darwinian,- to wit, natural selection and the survival of the fittest.— John 

 Phillips. We consider art questions altogether suited to our columns ; and shall 

 be glad to admit correspondence on such subjects as you mention.^S. P. Eastick. 

 Wc have been promised a paper on Faure's Accumulator by a skilful electrician ; 

 but there has neen great dehiy. If your suggested contribution were short 

 and simple, we should be glad 'to use it. Spare not illustrations nuch as the 

 Bubject may reouire.— Dixon Kkmp. Many thanks. We should be gUd to hear 

 of the resulta of your experiments.— Nkhton Cbosland. Can insert only por- 

 tions of your very voluminous letters. You misunderstand our comments ; but 

 not more than you have misunderstood the teachings of science.— Hbnby 

 SiooiN. We by no means intend to forget geology.— E. F. B. Habston. Thanks 

 for kind wishes. Query appears.— A. irBOOD. Many thanks for your offer, but 

 original matter, correspondence, queries, Ac., leave no room for reports of 

 lectures, which are nearly always unsatisfactory.— T. J. H. Your remarks on 

 *' Anti-Guebre's " letter are 'sufficiently sound, but he has been already 

 answered. Wonderful to relate, he sees and admits his error. We pay 

 wooderful, because when anyone haa allowed Diisapprebension to bloeeom 



into fali.e theorien, bis ci»e m too often past cure. Thorn are the mokineit 

 of a man of Mnencn in " Anti-Gmbre."— 8. 8. H. 8. Wr think it biHer 

 lo let our read»-ni inin in annwcring qui^tiotia eten on thtme- nibjecti which *•.- 

 hn\e specially fftudo'd. Where no f>ther antner come* wo shaU endeaToor t.. 

 supply the omistion, and nomelimei, a<« you may have noticed, we take ihe 

 initiative. Hut we «i^h tni" lo l>c a mo^zine of general knmvlodge. not a ni*Te 

 orRan for the expre-Kion of Mr. Richard A. Proclora opinion! on thine* in 

 general. JFe have, indeed, a number of qoevtiooa to oAk. only hitherto we hair 

 not been able to find room. Your quer^ about Bpihtuolism'i* omitted. W*- 

 could not find space for the eiidence which would pour in from all nidei, for »nd 

 n^'ainAt, still lesB could we find time to sift it, and without tifting, it would be of 

 little worth either way. Another que5tion is omitted a« not Quite suited to <>ur 

 jwgCTi. We must not offend even the weakest brethren. Mill lesi the weaker 

 histers.— K. C. R. Your letter about parhelia in lft79, ii lery inte- 

 resting, but crowded out by more recent matter. — K. E. ^<'I,'iT^.■. 

 Note answer to Mr. McOrigor Allan.— B. M.. F.R.A.3. Many thanki. 

 Your interesting stories of intelligence in animals shall certainly ' appear — 

 J. Parkeb Fowlbh. In the great pressure of more strictly scientific matter. 

 T hypothesis that ghosts and spectres, ef hoc genus oniae, may, perchance, be 

 »-. _-..!._- _ 1 --.1 _» _ ^ 1. . ^,^^ cannot appear 



r colu 



.lolct ( 



ultra red, and 



able to cert a 



any 



slight degree probable " We agree vrith you thoroughly, and also in considering 

 that it is original. "If it has ever been started before, we, like yourself, " have 

 never seen anything of it."— Habbib Rcssell. You will see that many starn 

 are named in the maps for this month. We may shortly find space for the noirn 

 you suggest ; but being astronomical ourselves, we 3o not wish to giye our 

 readers too much astronomy.— F. H. G. We hope to be able soon to gixe 

 short biographies of eminent men of science. Space is our trouble just no«. 

 As we grow we shall do all we can.— F. Cowlbt. Many thanks —B. C. Cowfli.. 

 No advertisements need be bound in ; of course there will be a litle-pnge.— P. M . 

 TrsSBi'LL. Compare the date of the passage you quote with that of Huxley s 

 later utterances about automatism in|animala.—EfN(jriBKB. ^Vhere do you get the 

 " hydrogen of the air " in sufficient quantity to account for the heaTy'minfaU? — 

 C. T. B. The Question of the infenority of woman has been now* sufflcientlv 

 discussed. Mathematical answer well known ; chemical answer inserted.— R. J. 

 BcBNsrnE, W. Most, and others. Thanks.— Mart B. Aldbb. See reply 

 above to C. T. B. Thanks.— J. D. Uabdt. We regret that space cannot 

 be found for your ingenious speculations about comets. Most probably 

 the coma may consist of crystalline particles ('* of the particular 

 nature belonging to the gas " forming the comet as a whole) ; but 

 the laws of optics will not permit us to regard the tail as produced in 

 the way you suggest. Moreover, the motion of the particles under solar at- 

 traction would not be what you suppose. Each particle would travel on its 

 proper ellipse as certainly as a planet would. AVe, unfortunately, must limit 

 greatlv the space we allow to the unsound, however ingenious, in order that we 

 may fceep room for scientific truths.— A. S. Fabqihabs^on. We would rather 

 not insert your query. Sleep preventatiyes are not rashly to be meddled with. 

 Better yield to nature's hints that she needs her " sweet restorer." — Amicus. 

 Y'our mathematical problem belongs to an easy class ; we have left it for our 

 mathematical readers to deal with. — D. C. Anderson. Your kind suggestion 

 noted. — W. H. Pertwbb. Have printed the passage you have kindly sent me; 

 recognised an old friend in it, as you will see. — Vbga. ' Thanks ; an ofevious mis- 

 take. — E. M. King. The article was not such easy reading as we coold have 

 wished; but the author is yen* eminent in that department.— J. A. L. R. 

 Y'our reasoning, which is perfectly sound, has already been employed (p. 8) . — 

 Wbather Gl'ide. a correspondent suggests that a weather gm'de might Vie 

 Iramed " without difficulty," in which the indications of the heavens, stars, 

 moon, sun, clouds, movements and cries of animals and birds, the human body, 

 plants, flowers, liquids, apparent nearness or distance of hills, &c., would help. 

 We beUeve such a guide might be framed, but not without difficulty. "Excep- 

 tions" would, probably, occupy the larger part of the guide. But the matter i» 

 worth considering. 



We are sorry to say that we continue to receive many letters calling attention to 

 the difficulty of obtaining copies of Knowledge. We can only repeat that we 

 have dime all in our power to prevent this, and that our publishers will be obliged 

 if subscribers will call their attention to the fact, should they experience an^ diffi- 

 culty in obtaining Knowledge at any of the railway book-stalls, or from their local 

 newsagents. To ensure a supply of the Back Numbers, which are rapidly becoming 

 scarce, orders should be sent without delay,— Ed. 



Knowledge. — Although we ofiFer our readers more in the way 

 of orijjinal matter (apart from correspondence, which is not to be 

 estimated by mere bulk) than any other jonrnal of similar price 

 and cliaracter, we wish to do better still. Wc hope so to extend the 

 circulation of Knowledge that we may be justified in enlarginj; 

 each number, in giving more illustrations, and in extending the 

 number of onr original contributors. To attain this cud ive need 

 the co-operation of our readers. Those among them who approve 

 our scope and plan can do more to improve Knowleuge than either 

 editor or publishers. If every reader were to obtain but one new 

 subscriber, not only would our circulation be doubled, but our power 

 to improve the matter placed before our readers would be increased 

 ii\ like proportion. If our renders will remember this, they will 

 follow the best course for making Knowledge what we wish and 

 hope that it may before long become. 



Contents of Knowledge Ko. 5. 



PAOB. 



Our Fields. By E. W. Preyost 85 ' 



Comets and Comets' Tails. [By the 



Editor— (///uWru/^-J) 86 



SoUds, Liquids, and Gases.— Part 



III. By W. Mattieu Williams 



TAGB. 



Missing Link— The linch Ord- 

 nance Maps-Pahzsch & Halley's 

 Comet— Do Comets obey Gravity ? 

 —The Crimson • circled Star — 

 Tables of Meridianal Parts. Ac... 9S 



of" Disease and Death. By The Eastern Skies in December— 



Dr. Andrew WUson, F.B.S.E.— {Itlusirated) 97 



Part II 89 Queries 101 



Brain Troubles.— Impaired Memory 90 Kephes to Queries 102 



Man a Fruit^ater 91 Training 102 



A Mild November 92 Our Mathematical Column lOS 



Cobrbsposdemcb.— The InyisibiUty , Our CheLS* Column 104 



of Light - Inclination of the Our Whist Column 104 



Earth's Axis- The Z«etrop©— The Aaawera to Correspondents 10« 



