1882.] 



• KNOWLEDGE 



153 



TOUT theory till I know what it is ? From your seeming to regard 

 apparent proximitT to the snn as eridence o'f real proximitr, I feel 

 doubtful as to rour power to solve what astronomers have 

 long regarded as one of the most perplexing problems pre- 

 sented to them. But all things are possible. Thanks for 

 pamphlet.— J. A. Oilaed. It never occurred to me to add 

 a likeness of " the editor " to Vol. I. Whenever I see my like- 

 ness (.') in magazines, Ac, I find myself saving (with the little old 

 woman of nursery fame) " Sure this isn't I .» "— H. F. W. I know 

 of no scientific men who bcUeve in lunar influence on the weather. 

 Many sailors and agriculturists do, just as many confirmed card- 

 players believe in all sorts of absurdities abont'lnck. Odd coin- 

 cidences, not directed by systematic observation, suggest these 

 false and fanciful notions.' Not one of the regular moon rules has 

 ever stood a year's steady testing.— T. A. " That water mav be 

 decomposed by electricity is well known: but that when large 

 masses of cloud are charged with electricitr the water in the cloud 

 13 so decomposed is not known, and that "the atmosphere around 

 such a cloud comes to contain hydrogen and oxygen in the right 

 proportions for explosion is altogether impossible. Even as ^an 

 acoustic phenomenon, it is only possible to exjilain thunder as 

 produced by the electric discharge as— in less than the thou- 

 sandth of a second— it traverses many miles of air. I share 

 yonr admiration for a thunderstorm; and I doubt whether there 

 13 the slightest appreciable increase of danger when we enjoy the 

 grandeur of the storm instead of shrinking into backrooms or 

 cellars. In most rases, too, death by lightning is absolutely pain- 

 less. The flash is not even seen ; for the optic uerre takes hundreds 

 of times longer to carry to the brain the news of the flash than the 

 flash takes to destroy life throughout the whole bodv.— Ax Edix- 

 ECRGH Sc^-scBiBEE. In this number appears an account, illus- 

 trated, of an inspirometer invented and described bv a correspon- 

 dent.— H. Askew. Yon are among those to whoni an apolo"y is 

 due for long-delayed reply. II. Pasteur is nnquestionablv a beHjvcr 

 in evolution, and recognises the truth of the Dar^vinian theorv as to 

 one of the chief factors in evolution. Probably whoever cited him 

 as an opponent of Darwinism, supposed Darwinism and atheism to 

 be synonymous terms, which, of course, is utterlv absurd. There 

 13 nothing atheistic in the modem doctrines of evolution any more 

 than there is in the older doctrines. The argument of the narrow- 

 minded runs thus:—"/ cannot believe in a Deitv if I believe in 

 evolution on the large scale, though my faith is not shocked bv the 

 growth of a plant or an animal ; modem men of science do believe 

 in evolution on the large scale, therefore modem men of science 

 are atheists." From this bad logic may be obtained the followin<' 

 syllogism in relation to Pasteur : — 



Bebevers in evolution are atheists. 

 ^ Pasteur is not an atheist. 

 .'.Pastenr is not a believer in evolution. 

 But Pasteur is a bcbeverin evolution, and Pasteur is not an atheist ; 

 nay, Pasteur finds himself led to reject atheism, chiefly because he 

 recognises the infinity of the domain of evolution. The God of 

 science, in fine, is Almighty and AU-wise ; shallow-brained, slope- 

 browed men, of the street-preacher type, therefore denounce 

 science as atheistical, and instead of savin;;, " I believe in God 

 Father Almighty, Maker of Heaven and Earth." thev din into our 

 e^ their -wearisome " Thou shalt believe in my God,'"' that is, in a 

 Uod fashioned after their o^-u image. The less cannot contain the 

 greater ; no hnman brain can conceive what God is ; science in 

 considering even the least of His works has come upon the un- 

 fathomable ; but those least of all can conceive of God aright, who 

 praise as God the Idol they have fashioned from their inner 

 selves. Their pretended zeal against science is, in realitv, anger 

 at the contempt which Science feels for the punv wrKiden idol thov 

 hare made out of their feeble brains. Yet auppijse thev are honest 

 enough though blind— or, at the best, bat-eved.— G." A. Stobey 

 (.ater, hithe work may come in for treatment. Jnst now space 

 • rbids; but many thanks— Xemo wants to leam how lookiiig- 

 ;i3ses are silvered.— Johx Geeexfield. Yes ; Laplace and 

 i.:i,grange proved that the planets, so far as gravitation is con- 

 cerned, may continue nio\-ing round the sun for ever. That is very 

 different from saying the universe can last for ever. Your own 

 communication showed that yon referred to heating and lighting as 

 weU as movement. I am conscious of no irresistible intlnence 

 ' nusmg me to object to "solar rays moving in circles in space." I 

 ■'iw only that, so far as telescopic vision h.is extended, rnva of 

 -lit and heat go straight. Surelv it was not verv severe to say of 

 -peculation involving the working round of sun-rnvs in enormous 

 ■ roles that it is rather vague. How large are these circles ? In 

 ^^ liat planes do they lie ? Whereabonts are their centres ? What 

 t irns the rays from their straight course? Whv does it 

 make them work in circles and not in some other c.irres ? 

 \\hen they have worked back, why should we not catch 

 'em coming that way towards the snn instead of alwavs seem- 



mg to come from the sun ? Such are a few of the questions 

 which occurred to me as I wrote the words, " rather vague." — 

 W. B. WiCKEN. Thanks ; but luminous paint is not available for 

 presswork at 74 & 75, Great Queen-street. Will insert your other 

 letter on tobacco and consumption if can find room ; but alreadv 

 before the last fortnight's letters even touched, we had 6ve or si.T 

 pages of correspondence standing over. — C. C, Jtx. I do not 

 know why gooseberry jelly changes colour daring the second boiling. 

 Some reader may be able to tell us. — A. Smith. Your remarks 

 about Great Pvramid too vague for any use. I hear with interest 

 that Prof. Piazza— usually called Piazzi-Smyth— has disproved 

 the tomb theory for the Great Pyramids. 'That he had tried 

 to, I knew; that he had done so is news indeed. For ont 

 who writes rather dogmatically (though you rather condemn 

 the Pvraniidalist's coincidences than any I have insisted 

 upon), your other question is rather mild. Have yon 

 really been 'bothered a great while" bv the difficulty 

 of finding the vertical angle of a cone formed' from a sector of 

 given angle ? Let r be the radins (which will presently disappear), 

 a the angle of the sector, which may be anything short of 2ir, then 

 the arc of the sector is ra, and as this forms the circumference of 

 the base of cone, we have radius of base = r -1. Now the slant 

 Bide is r. Hence the sine of half the vertical angle, which of 



ratio, and expressing it as a decimal fraction, you can at once 



obtain from a table of natural sines the scmi-angle'of the vertex. 



W. W. The points of the compass marked in my monthly star- 

 maps have relation to the earth only. The star-map shows what 

 stars lie to the north, cast, south, or west of a terrestrial 

 observer; which stars high up, which low down, and so 

 forth. The maps tell nothing of the position of the earth in 

 space. Your " plane of the heavens " is fully as mvBterious as 

 your "celestial compass." If you ask towards what p'oint on the 

 star sphere the earth is moving at any time, I can answer. The 

 earth is always moving towards that point on the ecliptic which 

 lies 90 degrees (or one quadrant) behind the place of the sun at the 

 moment. Thus on or about June 20 the sun is 90 degrws 

 in longitude from the first point of Aries. At that moment, 

 tlen, the earth is travelling towards the first point of Aries. 

 '• Whiiaker's Almanac " (a most excellent work) and anv star- 

 maps showing the ecliptic and marking the longitude" along 

 it (as my "Library Star Atlas." for instance, or the smaller 

 "Star Atlas") will serve to indicate the point towards which 

 the earth is at the moment travelling. Thus at the hour 

 of writing, July 22, at abont noon, " Whitakcr's Almanack" 

 (p. 42) shows that the sun's right ascension is 8h. Cm. 43s. Turn- 

 ing to one of my atlases, I find this point to lie very near the first 

 point of Leo, marked in the map with a lion's tail and also with the 

 number 120 degrees. (Tliis is in Jlap VI.) Going back 90 degrees 

 along the ecliptic, which, as the border nnmbcrs show, carries ns to 

 Map rV., and thence into Map II., I find that the earth is now travel- 

 ling towards a i)oint of the star-sjihere near the first point of Taums, 

 lying near the place where the three constellations, Aries, Pisces, 

 and Gctus, meet.- W. WiLsox, LL.D., Ac. I cannot at the moment 

 find a passage I noted in which Mitchcl (not Mitchell) confounds 

 the parallelogram of velocities (a kinematical) with the jiarallelo- 

 gram of forces (a statical), law. Ent in looking for it, I came 

 (at p. 135 of his "Orbs of Heaven") across a passage where he 

 confounds the latter with the second law of motion (a dynamical 

 law). His account of the so-called centrifugal force on p."l37 is as 

 unsound as Joyce's. The supposition of two forces mutually de- 

 stroying or counterbalancing each other, where in reality there is 

 but one force causing the body to deviate from the straight line in 

 which it is travelling and would otherwise continue to travel, is 

 essentially unsound. The account of Newton's demonstration of 

 the law of gravitation is full of mistakes. The account of pcndnlum 

 experiments for showing that the force of gmvitv is exerted by all 

 the particles of the earth's globe (pp. 148 and" 149) is altoge'thor 

 misleading, — utterly valueless, in fact ; while precession and nuta- 

 tion, the most effective proofs, arc left entirely unnoticed. — W. M. 

 I rather like the idea of a paradox column. 'TIic study of pnra- 

 doxers' absurdities serves some useful pur|X)ses. I have often 

 noticed that the misapprehensions which cnnsc a Newton Cros- 

 land, a Hnm|>den, a rarnllax, and such folks, to bud forth 

 into new and nonsensical theories, arc really entcH.nined, though 

 without leading to so prejiosterous a result, by many well-edu- 

 cated persons, who have studied scientific matlors insuflicicntly. 

 — W. G. We cannot well do sums, so many are sent us, and 

 many times ns many would be sent if we "worked all. Then 

 those you send are go clementarv. AVith regard to the last, 

 involving a difficulty, note that the equation (l-a-)-' -1 +i + j» + x' 



