Feb. 17, 1882.] 



KNOWLEDGE ♦ 



347 



of raw, trichiniforous pork is the chief cause of the propagation of 

 the entozoon to man ; but tlie parasite is not easily killed, even by 

 cookiug or salting. A temperature of 144° to 155 Fahr. kills the 

 free trichina?, but those encapsuled demand a greater heat. 

 (Fiedler.) — During conking, a temjierature which will coagulate 

 albumen (150° to 155° Fahr.), renders the trichina' incapable of 

 propagation or destroys them. As a practical rule, it may be said 

 that if the interior of a piece of boiled or roast pork retains much 

 of the blood-red colour of uncooked meat, the tenijici-ature has not 

 been higher than 131° Fahr., and there is still d.anger. Hot smoking, 

 when thoroughly done, does destroy them (I.cuckart) ; but the 

 common kinds of smoking, when the heat is often low, do not touch 

 the trichimc (Kuchenmeister).— Chas. Boyle, M.B. 



[275]— Asbestos P.vixt .*xd the Safety Lamp. — The prinGijile 

 of the Dav)' lamp is that tlie heat of the ignited gas within the 

 lamp is absorbed l)y the wire ganzc before the incandescent par- 

 ticles can pass through it. If you w^cre to coat it, as you say, with 

 a non-conductor, it would at once lose this power of conducting 

 heat away from the flame. The particles of gas would pass through 

 the meshes before they were cooled below flashing point, and an 

 explosion would ensue. No. What you want is, if possible, to 

 improve the conducting power of the wire gauze, and also to 

 increase its capability of radiating heat.— C. H. Wingfield. 



^nfiUins; to Corrrgpontifnts. 



)mmiintcntions for the Editor requiring early attention ghoidd reach the 

 before the SiiturJat/ preceding the current iainie of Knowledge, the 



irculatioH o/u-hich compels us to go to press early in the iceck. 

 Burns TO CoBRESPONDSNTS. — 1. Xo qiiesiions asking for scientifc information 

 cam be answered throvgh the post. 3. Letters sent to the Editor for correspondents 

 cannot be fortcarded ; nor can the names or addresses cf correspondents be given in 

 ansver to private inquiries, 3. A'o queries or replies savouring of the nature of 

 •dvertiMements can bt inserted, 4. Letters, queries, and replies are inserted, unless 

 contrary to Rule 3, free of charge, 5. Correspondents should tcrife on one side 

 onljl of the pi'per, and put drawings on a separate leaf, 6. Each letter, query, or 

 nply should have a title, and in replying to letters or queries, reference should be 

 ttade to the number of tetter or query, the page on which it appears, and its title. 



L'. G. There is a misprint, no doubt. Hydrogen, not oxygon, 

 must be meant, when it is said that 100 cubic inches weigh 

 2.14 gr.; or else for 2'11 read 32'14, though this is not quite right, 

 it would be about 3442. — W. H. Bosser explains that the to])- 

 gallant forecastle is that part of the forecastle where they work the 

 anchors, and where there is generally a windlass ; also, that when 

 the royal mast is a fitted one, there are top-gallant cross-trees. 

 Thanks. We had not known.- — E. F. B. Haeston' says sailors mean 

 simply "very high' bj- top-gallant, as top-gallant head-gear — a 

 woman's bonnet. — Ukrbert Weightmax. In line 8 from bottom 

 of 1st col., p. 3U7, and in line preceding the final result, the v in 

 denominator of second fraction within brackets should be deleted. 

 The mistake arose in making clean copy for printers. — Woxderfcl 

 Phenomenon'. The calculating boy himself in that case (G. P. 

 Bidder) c.xjilained how he worked, but, of course, not why he could 

 work so quickly. — H. L. says, readers who want their papers cut 

 will want next to have them read aloud. He compares them to 

 the sturdy beggar, who, having been given a penny to get 

 bread, said: "It will be very dry; you might give us a 

 drop of beer to wash it down." — C. J. C. Not Lord Rosse, 

 bnt earlier astronomers proved moon uninhabitable. — A. R. 

 Bbooks. I should say, invest about £4 in a good achromatic 

 object-glass, £1 in suitable eye-glasses, and fit them into tubes, 

 which you coald make yourself after the manner shown at p. 275. 

 — Phcexix. We must not trench on the department of our medical 

 contemporaries. We should be flooded by replies, among which 

 some might be untrustworthy, and a few unintentionally mis- 

 chievous. — Jas. A. Gee. Read Darwin on the " Formation of Vege- 

 table Mould through the Action of Worms." — Lewis J. Coles. 

 Thanks. — E. Malax. Question would involve four or five pages 

 of replies. — Stuart Mukray. Could you not say that shorter ? — 

 P. B. Holt. Kindly make a neat query. — T. S. Unfortunately 

 for your position, phrenological theories have been disproved, 

 not neglected, by science.— C. Grimshaw. In American houses, 

 none of the suggested effects are noticed. As for the open fire, with 

 its draughty ventilation, it is a disgrace to our civilisation. After 

 1 enjoying the comfort of well-warmed houses in America, -with a 

 mnter temperature often falling to 20 or 30 degrees below zero, I feel 

 ashamed when I think that in England a winter in which the ther- 

 mometer falls 4 or 5 degrees below zero leaves us shivering hope- 



lessly (half roasted on one side), even in houses intended for the 

 rich'Cand at thrice the cost for fuel).— Vacnol. Fear Mr. Williams 

 cannot tell us why fleas or their flatt er allies prefer some folk to others, 

 or why some fool their bites more than others.— W. G. Woolcohbe. 

 Should say that with your mathematical knowledge, Herschel's "Out- 

 lines" would bo far more interesting than GuiUomin's " Heavens. 

 I have revised the hitter book ; but, written as it originally was 

 by a non-mathematician, revising can be but patchwork. After 

 reading his carefully illustrated explanation of the way in which 

 one meteor-stream could explain both the November and August 

 showers, a mathematician puts down the work, knowing no original 

 opinion by a writer who could make such a mistake can be of any 

 value. An ordinary mistake proves nothing ; but such a mistake 

 as this carefully wrought out in details can only be interpreted in 

 one way. Yet the descriptive portions of the work are very good. — 

 MA.I0R Jas. Cummixgs would like to know where ho could purchase 

 such a blowpipe as Lieut. -Col. Ross describes, and wishes for further 

 information and illustrations respecting the apparatus described in 

 Lesson 2. — Sciextia cum Legibus. Believe it has boon shown tliat 

 scents may be emitted for very long periods without appreciable 

 loss of substance bvthc scent-emitting substance.— E. Taylor wants 

 name of a work on wild flowers and plants, with descriptions en- 

 abling beginner to distinguish them, to cost about 2s. 6d.— Notes 

 Unsigned received respecting moisture in air, effects of tobacco, 

 natural philosophv, and the atomic theory.— Gorgon. Whether 

 nose or ears can be changed in form by reiterated daily compressing 

 is hardly a question suitable to these pages. Try the Lancet (the 

 paper, not the instrument), or the Medical Press and Times, Should 

 say the story about fall of manna in 1846, at Yenishebir, must be a 

 canard.— W. A. C. It is unfortunate, but matters seem so arranged 

 that unless some animals die, many human beings must perish. 

 Teredo. Could the sides of an ancient river valley have the re- 

 quired flatness ? The natural interpretation is, that the terraces arc 

 parts of sea beaches which have been displaced later from horizon- 

 tality. — J. Rae. F. R. A . S. has explained bis meaning.— CnAs.BoTcE, 

 M.B., exjilains that opium only assists the action of purgatives (in 

 cases of lead-poisoning) by relaxing the contraction of the intestines, 

 but does not itself act as a purgative.- Comet. Yes : comets obey 

 gravity. The size and mass of a celestial body in no way affect 

 its motion ; a pin's head (or a pin) sent off with the right velocity 

 would travel in an orbit a million times larger than the earth's, with 

 as perfect steadiuess as the most massive planet.— T. R. A. Fear 

 cannot at present find space for articles on mesmerism, though am 

 very certain you would treat the subject from a scientific stand- 

 point.— F. F." Question too vague. Besides, it is not fair to ask me 

 what books I recommend on subjects upon which I have written 

 myself.— S. S. wants Mr. Matticu Williams to tell him how ts 

 warm a room 13 x 13 ft., which has no fireplace, and in the walls of 

 which no holes can bo made for stove-pipes.— Student. Story 

 about inherited kleptomania in a dog rather too long for us.— 

 T. R. Allinson. Thanks ; but questions already answered. Your 

 replies not numbered.— Charles Dawe. The question whether 

 snakes swallow their young in time of danger is rather well worn. 

 The usual opinion of naturalists is that there is no foundation for the 

 idea. The story you mention about the young who had eaten their 

 way out, after being swallowed, seems very hard to take in. Let 

 us hope it is not true.— F. H. S. No more room for magic squares. 

 — EcLECTicus thinks W. S. C'.'s reply to his letter, p. 202, too vague 

 to be of use. We have not spac3 to repeat the question.- Simplex. 

 Your account of Bell's system of shorthand too abstract for our 

 readers, and too long ; we wanted only a few simple illustrations of 

 its characteristics, as compared with those of Pitman's.— J. F. S. 

 Thanks. Wish we could do more that way. The correspondencB 

 stops the way. Fear can find no space for letter already printed.— 

 A New Re.vder. Thanks; but new subjects of correspondence 

 leave no room for the old ones you discuss. — W. H. K. Soames. 

 Yon go a little beyond what I had thought possible in the line you 

 take. When, first, scientific discoveries seemed diSicult to reconcile 

 with certain passages in the book you mention, men of your way of 

 thinking said simply the earth is not a globe, it does not niova 

 round the sun, and so forth, because this book says differently; we 

 want no other evidence : so they rebuked men of science for 

 teaching such things, and told them to be still. When, however, 

 men of science had demonstrated the soundness of their views in 

 those matters, your friends took another line. " These facts," 

 thev said, " are right enough, and the account in the book, rightly 

 und"erstoo'd, agrees perfectly well with them." So they rebuked 

 men of science for saying that the facts did not agree with tha 

 book account, and told them again to be still, as not knowing 

 how to interpret the book. Men of science had not said what 

 they were rebuked for saying; but that was a detail. It is, 

 however, a new thing — so far as I know— to take your line ; 

 and to tell men of science that they are bound to show 

 that the account in the book is incorrect before they indicate 



