J AS. 13, 1882.] 



• KNOWLEDGE * 



237 



Groningen, 1875. Prof. Ogdcn Rood's book on " Modem Chro- 

 matics " (Kegan, Paul, & Co., price 5s.) is far better worth study- 

 ing. — Er.nest J. Wer.vdam. There aro manj- proofs, aud as many 

 disproofs, of the tlieory tliat character can be learned from tho 

 liandwriting. The method has no scientific interest. — B. Dox- 

 BAV.1ND. We insert one of your letters, but yonr last, on the 

 colours of animals, is too long, and we have not time to abridge 

 it. You take three pages of MS. for initial sarcasms against a 

 valued correspondent, who has really shown a verj- kind 

 desire to explain matters; another to show that "a tank 

 naturalist must be contemptible in all the ins and outs of 

 him"; then possibly yon come to business. We cannot say — 

 life is too short to get through more of such letters. Stay. Wo 

 will not at once consign your letter to W.-P. basket, but only 

 the tirst four pages, keeping the rest for another trial when we 

 have refreshed ourselves with matters more ud reui. Understand, 

 you are as free to say in so many words that Prof. Wilson seems 

 angry, as he was to say that a remark of yours seemed to him 

 silly. But we cannot find space for elaborate sarcasms. We 

 want to get at facts, and invite our correspondents to join in tho 

 work, not to try who can say the smartest things. — M. E. 

 Pe.vdrep. It would take much more time than we can afford to 

 go through your letter of some score of closely-wTitten pages, 

 scoring out all that is not to the point ; and we can only insert 

 what is to the point. — J. H. Symixgto.n. We misunderstood you 

 about the Collie. Excuse us. — H. A. Bclley. Lunar influence on 

 weather is conceivable, though never sho\vn to be really effec- 

 tive ; but planetary influences, or the absurdities called Astro- 

 meteorologj-, we cannot even discuss here. We must draw the 

 line somewhere. — Z.iees. Dr. Ball's experiment, of dropping 

 one of his namesakes on the floor of a railway carriage, has alto- 

 gether the advantage over yours of firing a bolt from a catapult. 

 How did you test the horizontality of the bolt's flight, and how 

 eliminate effects of atmospheric resistance ? We are sure, when 

 we drop a ball in a railway carriage, that its only initial motion 

 is horizontal, and that air-resistances are the same as on a body 

 let fall from rest. — PiLUL.i. You are evidently not aware that 

 advertisements of the kind cannot be refused. — C. J. BaowN. 

 " Assuming the earth's diameter to be 8,000 miles," (or 8, or 

 8 millions, if preferred,) the pressure is greatest at the centre. — 

 R. W. If the solid be transparent, farther edges should be 

 shown like nearer. The cases are different. Science finds no 

 evidence of man's having become degraded. It does find evi- 

 dence that some creatures have. — Jas. Elias. Your letter is too 

 long for insertion ; but your idea is well worth considering, that, 

 in some cases, frog's spawn might have been deposited in some 

 fissure where running water passed, and so a tadpole develops 

 there, which, adapting its mode of living to its narrow surround- 

 ings, would become a frog, and might live comfortably enough. 

 A quarryraan, as yon say, would not be apt to notice the fissure, 

 and the stone would nattirally split in a plane running tlirough 

 the cavity. — H. D. KixcnON. Quite impossible to appoint meet- 

 ing. — Daniel Jackson. Gambling on the Stock Exchange is 

 undoubtedly no better than gambling elsewhere. The two books 

 you refer to are the " Expanse of Heaven " and " Infinities Around 

 Us," published by Chatto. — J. K. Mellor. Thanks, but fear 

 we can find no space for biographies at present. — Jas. Douglas. 

 The change of eccentricity of earth's orbit, and not the pro- 

 cessional reeling per se, causes changes of climate you men- 

 tion. — E. W. Will try to find room for your letter in full. 

 In the meantime, we may note that the applications of the 

 differential calculus to Physics are so nmch more difficult 

 than those to ordinary mathematical problems, that the 

 course pursued in books seems natural enough. Do you mean 

 to say that, given the linear dimensions of a curve, and the 

 length of the limits between which you integrate, you find 

 difficulty in ascertaining the number of square inches, feet, or 

 miles in the area ? I cannot see where the difficulty comes in. 

 In a series of papers I once wrote on the calculus for the English 

 Mechanic, I showed how a number of problems in everyday life 

 may be dealt with by means of it. The translation of the symbols 

 into concrete quantities should be one of the first, not one of 

 the last, things to which the student's attention is directed. — 

 A Xew Sl'bsceieer. We shall presentlj* give a description of 

 some comets of the present century ; but we must refer yon to 

 treatises on comets for an account of all, or even of the principal 

 comets. — Pleiaiie.s. (1). It is better for querists to give their 

 real name (not for publication), but, not essential. (2). We 

 may presently give weekly notices of astronomical phenomena. 

 (3). No. 1 of Knowledge has now been reprinted for tho 

 third time ; the proprietors are not likely to reprint again, so 

 that if 3-0U wish tor No. 1 you should apply in goo<l time. (4.) 

 '• Abstract " in headings of letters means that we have had to 

 abridge them. — One Wishful to Learn. Heat is not generated 



at the sun by his attractive action on planets. When a cord is 

 pulled, or a bar either pulled or pushed, the heat is generated 

 by the impressed forces, i.e., comes from without. — E. B. T. 

 Thanks, but the idea is much older than Babbage's time,'or — R. F. 

 Gardiner than Rev. Mr. Hitchcock's.— W. Hardy. "Dietrichsen's 

 Almanac," no longer published ; " Nautical Almanac " for 1882, 

 1883, 1884, and, probably, 1885, can be obtained of Murray, price 

 2s. 6d. each. — Florence E. Boyce. Pray excuse us for "leaving 

 yonr interesting communication so long unnoticed. It got lost in 

 our troubled sea of letters, MS., &c. The proof for sum of 

 squares is verj' neat. — Arthur Vizard. Your remark answered 

 by last number. But the analysis of chess openings need not 

 be hurried. We mnst not make a toil of pleasure. Chess and 

 whist are our scientific recreations. — F. H. S. Have been 

 obliged to limit answers to magic square questions. — J. RusSELL. 

 How far should we be advanced if we agreed to regard comets 

 as having " the same place in tho inanimate solar system as 

 is occupied by jelly-fish in the animal world ? " — J. Sharp. 

 You article somewhat too diffuse, and much of its contents 

 generally known. — Ursula. Reply to query about rainbow on 

 page 212, second column, lines 11, &c. — Lewis Arundel. 

 Your remarks about my replies to 153, Ac, remind me some- 

 what of Moliere's "Nous avons change tout cela." I was not 

 answering " according to Cuvier," but according to Owen and 

 other more recent authorities. In exjilanation of a certain 

 property of worms, I referred to their being articulated. Do you 

 conceive that when worms were formed into a sub-kingdom 

 Vermes, they cca.sed to be articulated, or that the chain of 

 ganglia I mentioned ceased to be present in their annelidan 

 bodies ? They have no articulated limbs, but they arc articulated 

 animals whether classed as Artliropoda or Vermes, whether called 

 Abranchiate Annelidans, or common earthworms. Equally, 

 classing toads and frogs as Batrachian Amphibia has not made 

 them change their reptilian habits. — D. C. Jones. Recently 

 answered, — A. T. C. Pardon me for repeating that there must 

 have been something near or far off between the sun and the holes. 

 In saying that the sun's light ceased to pass through the holes 

 (there being nothing between the holes and the opposite wall at 

 the time), you in effect say that something intercepted the sun's 

 ravs. If you insist on it that there was nothing between the sun 

 and the blind to cast a shadow — cloud, flight of birds, or of 

 dust, or of leaves, or flying object of some sort, near or far off — 

 all one can say is that nothing can explain what you saw. No 

 shadow ever yet existed ivithout something to cast it. — Major. 

 The illusion about letter S is well known to proof correctors. The 

 lower half looks very much larger upside down. — C. F. B. The 

 reason why the sun and moon appear larger when near the 

 horizon is, I take it, because the heavens appear to form a flat- 

 tened not a spherical dome, and tho sun or moon subtending 

 really the same angle when near the horizon (appreciably) seem 

 to be' nearer than the sky beyond. The eye seems to misinterpret 

 what it actually sees, making the sun seem nearer instead of the 

 sky seeming farther. 



flott^ on !^rt anil ^n'cnre. 



Mr. J. H. A. Macdonald, Q.C, tho late Solicitor-General for 

 Scotland, has constructed an " electric holophote course indi- 

 cator," which he has lately been exhibiting in Edinburgh. An 

 electric light with a reflector is placed in a prominent position on 

 the deck of the vessel, and is controlled by the movement of the 

 helm. The direction of the powerful beam of light indicates the 

 course of the ship, and at the same time shows whether or not the 

 sea is clear over a large area. The model is to be shown at the 

 Crystal Palace Exhibition. 



Mr. Jacob Reese, in a paper read before the Engineers' Society 

 of Western Pennsylvania, remarks : " The great want of the present 

 a"e is a process by which the static caloric of carbon may be set 

 free by non-luminous combustion, or, in other words, a process by 

 which coal or oil may be oxidised at a low degree within an insu- 

 lated vessel." This "cannot be too prominently brought forward. 

 "If it can be accomplished," as Mr. Reese says, "we would be able 

 to produce from twelve to fifteen million foot pounds of electricity 

 from one pound of petroleum, or from ten to twelve million foot 

 pounds of energy from one pound of good coal." — Atheneeum. 



Abe Bees a Nuisance ? — An unusual case is being tried in the 

 Cumberland County (Penn.) Court this week, that of testing by a 

 jury whether the keeping of a large number of bees in a town or 

 borough is a public nuisance or not. The case is from West Fair- 



