118 



KNOWLEDGE 



[July 11, 1882. 



fancies lip must — pive in ; and from nny distuni-c, at nny pnins, ho 

 returns, penerallv to find that his fears have been wholly pronnd- 

 loss. Only those who have either themselves experienced this 

 tloobt, or repeatedly watched its Rrowth or witnessed its effects iu 

 others, can imafnno how terrible in itself, and what a prolific source 

 of mental mischief, so seemingly small a matter may prove. It is, 

 in f»ct, the first and warning symptom of many a grave, and — 

 beoatise neglected — afterwards incurable case of mind disease." — 

 J. Mortimer Granville. M.D., in iVood U'erdi. 



From observation, 1 think that the more thoughtful and intelli- 

 gent persons are generally the victims, and indeed, after reflection, 

 it seems natural it should be so. I should like to see this subject 

 discussed in your columns, and to know the canse of it and the 

 cure. ' W. M. M. 



VABICOSE VEINS AND CYCLING. 

 [4G9' — I have head it said that medical men attribute the groat 

 prevalence vt varicose veins to the use of bicycles and tricycles. 

 I shall be glad to know if there is any truth in such a statement. 



A Teicyclist. 



TUE DOUBLE STAR, CASTOR. 



[470] — May I be permitted to suggest with regard to your reply 

 to " Eicclsior," on p. 83 of Knowlkpgk, Xo. 35, that the fact that 

 "no sensible change has taken place in the relative position or 

 distance of the principal star and the 11' one since the year 1823" 

 (1829 ? U. and So's results are coufisscdiy not very accurate here), 

 tends rather to imj.ly a physical connection than an optical one. I 

 think you will find that the system is not "universally regarded 

 among astronomers as being simply binary," because this small com- 

 panion shares in the proper motion of" Castor in the same way as 

 the little pairs ;i' BOotis or i: 518 share in the P.M.'s of ^' Biiotis 

 o' Eridani ; all three being probably tcrnarj-. U. SAULEK. 



[F.R.A.S. wrote the reply in question, not The Emtoh.] 



MEDICAL WORKS. 



[471] — "Enquirer" would bo glad if any of the readers of 



KsoWLEUCF. would inform him if any societies similar to tho " New 



Sydenham," i.e., societies which issue works on medicine and allied 



sciences to subscribers, and terms of subscription. MEDICUS. 



AN ARTISTIC DOG. 



[472] — I send you the follon-ing instances of what may bo called 

 artistic appreciation in a dog. Jly dog, on whose ambiguous descent 

 " Skyey influences " have undoubtedly operated, jiointed in a 

 marked manner at a Japanese figure of a cat, in which the mons- 

 trous was blended mth tho life-like. It stood on the floor insido a 

 ■hop, and I Imd to call tho dog off just ns I might had tho creature 

 been alive, not before the dog had evinced more than curiosity. 

 Again, tho same dog came nncxpectcdly upon a life-sized plaster 

 bast of a man standing on tho pavement. This aroused his atten- 

 tion, then surprise, and nltimately fear, or indignation ; in fact, ho 

 barked in a way that reminded ni'e of tlio lato Frank Matthews as 

 Qoince, on meeting Bottom "translated." 



It is clear that tho dog's sense of form alone was appealed to, as 

 neither object wag coloured in at all tho natural tints of the 

 respective originals.— Vours, Ac , J. I'owEU IIk.k.s. 



CHANGE OF COLOUR IN lll.OWl'lPE BBAD.S. 



[173]— The colour of beads before the blowpipe is to bo attri- 

 batcd to the luminosity, or vibratory motion, in tho beads them- 

 selves, and not to reflected light rays. 



In the case of the cooling gold bead, tho molecules become con- 

 densed, therf;by shortening their period of vibration, and causing 

 the Ipminosity of the bead to run up tho gamut of colour. So in 

 tho bismuth bead, the expansion of tho free path of the molecules 

 lengthens their vibratory pericd, and tho light runs down the 

 gamot. 



Is it not possible that at various strings, when stretched, will 

 pick out each its own note in a harmony of sound, and respond to 

 it ; so all matter shines— I have no other word— with the colour 

 its vibratory period selects from the harmony of light ? 



Aug. W. Ork. 



TELEGKAl'H via BEHRING'S STRAITS. 

 '471"— Is it practicable to build a telegraph line ns far north as 

 Bchring's Straits, and then a cable to America ? There is one to 

 Uammerfest, in Norway, as far north. Such a route would have 

 the KTr^t advantage of a short cable, which could be multiplied 

 indefinitely at little cost, and would, 1 presume, work quicker than 

 a long one owing to the less induction. J. p. 



9ns(U)fi£f to CorrrsponlirnW. 



the Editor requiring earty attention rkould reach the 

 Office on or before the Sitturdtit/ prtcedtnij the current ieeue qf Knowledsb, th» 

 increaeimg circnlution nfithich compete ur to ffo to preet early in the vceic. 



HllcTs TO ComsroKnuHTS.— 1. A'o queitioni aetcing for ecientijie tti/brmnKoi* 

 can be anrvered through the poet. 2. Leitere eent to the Kditor for corrcepondente 

 cannot be forwarded ; nor can the namee or addreeeee cff correepondente be given in 

 anewer to private inquiriee. 3. Correepondentt ehoutd ecrite on one eide only of 

 the paper, and put draieinge on a eeparate le^f. 4. Kach letter ehoutd huve a title, 

 and lit replying to a letter, r^erence ehould be made to ita number, the page on 

 which U appeari, and ite title. 



LiKi'T.-CoL. Ross. Yonr opinion that " Knowledge " is " tho best 

 twopennyworth that England over had " is very gratifying ; but I 

 am obliged to decline further Green Beam and Blowpipe papers. 

 Your views on the former sulijoct I know to be incorrect ; of the 

 latter subject, so far as practical blowi)ipo work is concerned, I 

 know nothing; but space will not permit of further articles on a 

 subject in which few, I fear, tnko interest. — Stellabum Vox. (1) Tho 

 astronomical views of Tycho and Kepler were not without tincture 

 of astrological fancies — natural enough in their time. (2) Astrology 

 has no basis whatever in scientific facts ; one cannot siiy it is not; 

 " a correct science," for it is not a science at all. (a) As held by 

 the earliest Chalda?an observers, it may Imvo been associated with 

 a flat-earth theory ; but the later Chaldaan astronomers recognised 

 the earth's rotundity. (4) It is not " worthy of any credence 

 whatever." — T. R. A. You do not seem to have noticed that an 

 account of tho mastiff Kepler's arithmetical feats is given in the 

 series of articles on Intelligence in Animals. The work you mention 

 is in hand for review. — R. Ellis. Y'our poetical account of 

 medical story suggests something rather "dreadful." If you will 

 kindly consider that among our readers arc many of tcuder souls and 

 sensitive nerves, and so " do your spiriting gently," 1 have no doubt 

 the story would be very acceptable. Tho returned proof is suggestive 

 of a liveliness of imagination provoking to constant improvements. 

 But printers have a pleasing way of introducing tho letters, L, S, 

 and D, in connection with such changes. If every cDlmnn of 

 K.NOWi.EiiGK wore treated that way, I fear it would bo iiniirovi'il off 

 tho face of the earth. Thanks all tho same.- Anxioi .s I'uiknd. 

 Exceptional care is taken about such advertisements as those. Iu 

 the case you mention a sample packet was ordered, which proved 

 <|uite unolijoctionable. — Jas. Deas. I do not remember anything 

 ill your communication which was similar to tho very striking 

 achievement of Casoneuve. As far as I remember, yonr account 

 related only to parlour expel imcnts, which may always bo "got up" 

 by tho invention of simple signal codes. I think, however, it was tho 

 pait SM).'trl■^t in;,' animal magnetism which seemed to mo to render 

 yni;i , ti,t I,: i. i 1.111— which was rather long — unsuitable. Pray 

 I" li 1 1 at there was not tho least intentional disparage- 



niri \] I , , kttcrs reached mo on tho same subject about 



tlia' I ill [i I . |inios rather careful discrimination to draw tho 



lino liein cell wli.it may bo useful as scientific evidence, and what 

 may not. Of course, H. M.'s evidence by itself may bo open to 

 exception. Uis friend may have boon also a friend of tho con- 

 jurer's. Ho himself may have forgotten some details. And so 

 forth. But his amount accords well with the evidence given by 

 Dickens. (I believe it was tho same conjuror in both cases.) On 

 tho other hand, general accounts of thought-reading at evening 

 parties, where tho narrator " is sure there was no deception," 

 are really of no valuo from a scientific point of view. An 

 exact account of precautions to prevent deception should bo 

 given. (They were unnecessary in II. M.'s case, which depends 

 solely on his own veracity and the trustworthiness of his friend.) — 



II. W. Faucus. There can be no doubt that when largo masses of 

 aqueous vapour are suddenly condensed into the cloud form, or largo 

 masses of cloud still further condensed by tho gathering together of 

 minute water-drops or vesicles into largo rain-drops, electricity is 

 generated and vicc-vcrnd. It can also be shown experimentally that 

 when oxygen and hydrogen in due proportion aro converted ex- 

 jilosively into water, electricity is generated. But tho theory that 

 lightning and thunder are caused by tho explosive change of oxygen 

 and hydrogen in tho air into water is quite inadmissible. Hydrogen 

 and oxygen nowhere exist in the air in tho right, or anything like 

 tho right, proportions. — W. M. M. Thanks. Your letter shall appear 

 shortly. — Postcakd. You certainly have entirely misunderstood our 

 notes " On Some of Our Critics." We wish every reader who bcoh 

 any mistake, or thinks hO'docs, to call our attention to it. We have 

 been rather careful to show this. It is only tho icay of making cor- 

 rcctionswhich is in question. Compare thctwo following corrections 

 on tho same subject, and you will see that while one is not only 

 admissible, but useful, the other is not so well : — 



(1.) " It appears to me that Dr. Wilson's use of the term quad- 

 ruped as synonymous with mammal may mislead some of your 

 younger readers, though, of course, no biologist could for a moment 



