Jan. 6, 1882.] 



* KNOAVLEDGE 



207 



fLttUvi to ti)t eiiitor. 



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 Jdetsrs. Wyman Sf Sons. 



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All Letters or QMries to the Editor tehich require attention in the current istue of 

 KyowL^OQE, should reach the Publishing Office not later than ike Saturday preceding 

 the day ^publication, ^^_^^ 



" In knowledge, that man only is to be contemned and despised who is not in s 



8tate of transition Nor ia there anything more adverse to accuracy 



ihan fiiity of opinion." — Faraday. 



"There is no harm in makinff a mistake, but great harm in making none. Show 

 me a man who makes no mistakes, and I will show you a man who has done 

 nothing." — Liebig. ^^^^_ 



(Bnv Corrrsponlinur Columns. 



THE WEATHER FORECASTS.— PSYCHO. — TOADS STUNG 

 BY INSECTS.— BOOKS ON HISTOLOGY AND THE UN- 

 DULATORY THEORY OF LIGHT. — TABLE OF LOGA- 

 RITHMS.— DIAGRAMS WITHOUT DESCRIPTION. — PRO- 

 NUNCIATION OF "BETELGEUX." — THE COAL AGE 

 AND THE EARTH'S INTERNAL HEAT.— ANTIQUITY OP 

 MAN. 



[164]— The letter [124] of Mr. Spiller, on p. 140, is a very in- 

 structive one, and may well stimulate inquiry into the procedure of 

 that rather remarkable department, the Meteorological Office. I, 

 like Mr. Spiller, took considerable pains some time since to com- 

 pare the daily vaticinations issued from Victoria-street, with the 

 actual weather obtaining at the periods for which they were made, 

 and with the following noteworthy result. At first I found that the 

 predictions were very much more frequently wrong than right, and 

 this suggested the idea that the oflicials were on the track of some 

 law, but were merely misinterpreting it. Later on, however, I 

 came to the conclusion, in common with your correspondent, "that 

 they are about as often wrong as right." It is absolutely needless 

 to point out to any one with the least smattering of mathematics, 

 what this indicates. Put shortly, it is that equally valuable 

 weather prophecies might be made- by the simple process of tossing 

 up a florin and calling "heads" fine and "tails" ^ormy. Now this 

 suggests to me at once, as a scientific man and as a taxpayer, that 

 the British public has a distinct right to know why it should be 

 called upon to pay £14,500 annually for such results as these ? 

 Moreover, it is rumoured that the office is supervised by a certain 

 " Meteorological Committee of the Royal Society," who divide 

 £1,000 a year among themselves. One would be pleased to ascer- 

 tain definitely what is actually done by these gentry for this modest 

 little sum. The Meteorological OiBce exists for the benefit of the 

 nation— not the nation for that of the Meteorological Office, and the 

 sooner this is realized the better for all those concerned. It seems 

 ridiculous that we should receive such accurate forecasts of gales 

 gratis from a New York newspaper proprietor, and that we should 

 be reading about the " calm," prophesied by our own paid servants, 

 while those gales are howling around us. As a very humble effort 

 towards the solution of this concluding part of Mr. Spiller's letter, 

 I would venture to suggest Payment by Results. 



May I say, in connection with the question put by W. H. B. 

 (letter 126, p. 143), that three or four visits to Psycho sufficed to 

 convince me that a small boy is concealed within the figure. Some- 

 thing I once observed through a powerful field-glass satisfied me of 

 this. 



Omithorynchus (query 100, p. 145), is'wrong in supposing that 

 toads are not affected by the stings of the Hymenoptera. 1 have 

 myself seen a toad stung by a wasp which it attempted to swallow, 

 its tongue subsequently protruding from its mouth in the form of 

 an inflated bladder, obviously causing it serious, if not very pro- 

 tracted, inconvenience. 



If D'Artagnan (query 103, p. 145), does not mind reading a book 



thirty years old, he may derive an immense amount of information 

 from Quekett's " Lectures on Histology." It was originally pub- 

 lished by Bailliere ; but one of the second-hand scientific booksellers 

 would be the likeliest place to procure it now. Dr. Lloyd's 

 " Elementary Treatise on the Wave Theory of Light," published by 

 Longman's, is excellent too, for the purpose for which he re- 

 quires it. 



To the list of books of Logarithms, given on p. 102, I should like 

 to add Cape's " Mathematical Tables," published by Longman in 

 18C0 (3rd edition), as the most convenient G-figure set -with which I 

 am acquainted. The arrangement is excellent. In the trigono- 

 metrical tables the successive differences are given for 100" instead 

 of GO", thus saving a quantity of calculation. I use these in my 

 observatorj-, and Chambers' in my library-. 



May I venture to suggest that Mr. Thorp's drawings on p. 100, 

 by themselves, are scarcely sufficiently explanatory of the instru- 

 ments they represent ? Notably Fig. 2, in the absence of verbal 

 explanation, fails wholly to show how an ellipse can be described by 

 the piece of apparatus delineated. It looks as though it must draw 

 a circle — and nothing else. 



In answer to query 107 (p. 167), astronomers, in practice, always 

 pronounce the projier name of (a) Orionis " Beteljews." 



"Ignoramus" (query 110, p. 167) should obtain and carefidly 

 read through that part of Page's "Advanced Text-book of 

 Geology," which treats of the Coal Measures. It is not now sup- 

 posed that the internal heat of the earth had anything to do with 

 the production of the carboniferous flora ; in fact, it is a grave 

 question whether such flora was, in any legitimate sense, tropical at 

 all. A humid and equable, rather than a tropical climate, would 

 seem to favour the tyjie of vegetation of wliich our coal measures 

 are composed. The earth's superficial temperature is quite un- 

 appreciably afforded by her internal heat (Fourier says ^th of a 

 degree), such surface temperature being practically wholly derived 

 from the sun. This influence extends to a depth varying from 60 to 

 90 feet. Don-nwards from this stratum temperatm-e rises 1 degree for 

 every 60 to 65 feet ; so that at a relatively short distance from the 

 earth's surface, it would seem that the most infusible rocks must be 

 molten. Possibly, the sun may one day cool down, and the earth 

 with it, but it will not be in " Ignoramus's " time, or mine either. 



Any one reading the isolated words quoted in inverted commas 

 from Sir Charles Lyell in reply 84 (p. 168), will imagine that he 

 did not believe in the great antiquity of the objects discovered by 

 Mr. Horner in Egypt. Those who have been misled into this belief 

 had better read Chapter III. of Sir Charles's own " Antiquity of 

 Man," as recommended by " Kemp" in the preceding answer. 



A Fellow of the Royal Astronomical Society. 



A CORRECTION: DATE OF MENES. 



[165] — I perceive that " A Member of the Society of Biblical 

 Archaeology" quotes Mr. Stuart Poole as an authority for the date 

 B.C. 2717 for the period of Menes. Permit me to say that Mr. Stuart 

 Poole has long since abandoned that position in favour of a much 

 more remote epoch, as may be seen by reference to his articles in 

 The Contemporary Revieiv for 1879. 



Anothek Member of the Society of Biblical ARcnj:oLOGY. 



PERSONAL IDENTITY versus TATTOO MARKS. 



[166] — Am I right in understanding that, owing to the Physio- 

 logical waste and decay, our bodies virtually change in every part, 

 so that our bodies to-day are not the same bodies seven years hence .' 

 If so, may I ask the following : — When a boy, I tattooed my arm 

 with Indian ink ; my body must have changed four times during 

 that time ; the design is as distinct and permanent to-day as ever. 

 Will some of your correspondents kindly enlighten me upon this 

 subject ? — Yours, &c. Walter H. Maguire. 



Dec. 5, 1881. 



P.S. — I wish your valuable journal every success. 



THAWING ICE. 



[167] — In a book which I have— a translation from the French 

 of Professor A. Cazin — the following experiment is described ; — 



" Take a piece of clear ice and place it so that a pencil of sunlight, 

 condensed by a lens, shall enter it parallel to the planes of congela- 

 tion ; then -with a microscope, placed at right angles to plane of 

 congelation, examine the illuminated part, in which many limiinoue 

 specks will appear, gradually increase in size, and send out little 

 branches, generally six in number and of varying forms, &c." 



I have tried this interesting experiment with several pieces of ice, 

 but failed to see any traces of these beautiful little branchlets. 

 What I saw was the specks of light rapidly increasing in size, and 



