ilAY 22, 1685.] 



♦ KNOWLEDGE ♦ 



■145 



li^ht, wUicli I hesitate to call auroral. It exteuiU-J nearly to 

 U. Maj. ami Leo; was perfectly steady; about ns briplit as the 

 zodiacal at its briiihtest ; and Imd the sun's place for its contre. 

 Small nimbi on it were black and well-detined ; in the south-west 

 dingy and ill-detined. The next evening after sunset there was a 

 pink after-glow. As these phenomena came after a week of stormy, 

 cold weather, they are probably terrestrial. I suppo.so my light was 

 a faint aurora : its apparent relation to the sun may have been 

 merely a coincidence. 



Every one knows how cold the second week in Hay u.sually is ; 

 but I have not seen it noticed that there is as often a spell of real 

 summer heat between the 10th and 2oth of April. It would bo 

 interesting to know if our antipodes experience these two periods. 



H.X LLIARDS. 



SOLAR UALO. 



[1718] — A very distinct halo was visible round the sun here at 

 one o'clock on Wednesday, May 13. This appearance much 

 resembled the more common lunar halo, but was more sharply 

 defined and proportionally brighter. The radius subtended an 

 angle of almost exactly 20°, and there was a yellowish iridescence 

 in the inner edge of the ring. The sky was hazy, and the pheno- 

 menon lasted for some time. P. J. Bt^vERiDGE. 



Ipswich, May 15, 1SS5. 



A COIXCIDEXCE. 



ri719] — Here is my latest "coincidence." As I once said, they 

 are frequent with me. 



Having been sitting writing for some hours, I got up — to fill a 

 pipe, say — and then standing before the fire, and looking at the 

 clock, it occurred to me that I had not wound it for some time. 

 Xow, winding my clock is a thing I never have done regularly — I 

 always forget ; but as it had been lately cleaned, and was in course 

 of being regulated, I did not wish it to run down when last winding 

 it, and so put a slip mentioning the date, <ic., and adding — as it 

 happened — the day, hour, and minute, when, according to an old 

 estimate, it should run down. Herein lay the coincidence, for on 

 taking out the slip and reading this, and then looking at the clock, 

 lo ! the hands of the latter indicated the hour and minute as 

 written, and the date also was the same. It was not about the 

 right time, to a minute or two more or less, but it was the very 

 identical minute. And I hereby declare that I could not before- 

 hand have said whether or not it was within two days even of the 

 proper time. It was ten days since the slip had been written, and 

 my memory is so bad that I only had a fancy that it was more 

 than a week ago, and might be ten daj's. Apart from the date — 

 the chances were 1,439 to 1 against the clock showing the right 

 minute. I may add that though the putting up of the slip as a 

 reminder was in itself not without precedent, the prediction on it 

 was quite so, to the best of my recollection. J. Heeschei,. 



[Is Colonel Herschel thoroughly satisfied that this is — in any 

 legitimate sense — a case of a mere coincidence ? because I am not. 

 It seems to me far more like one of " unconscious cerebration." — 

 Ed.] 



CLUB TANDEM. 



[1720] — In reply to " A Constant Header of Kn'owledge," I 

 should think that the new Club Tandem made by the Coventry 

 Machinists Company would suit his requirements best. This has 

 bicycle-steering for the gentleman and rack-steering for the lady. 

 There are very few machines that would suit him. Levi has also 

 a very good tandem for his particular purpose. 



In either of these machines a portion can be ridden as a single 

 machine, or the two combined as a tandem. Levi's is a hind- 

 steerer, Ijut perfectly safe. The Coventry Machinists Company's 

 tandem has a small wheel both back and front. 



I do not approve of any convertible sociable machines yet made. 

 Tandems are faster, lighter, stronger, and much more portable ; 

 they only require a little more careful riding. John Browning. 



THE SCOPE OF KNOWLEDGE. 



[1721] — The editorial groan in answer to me (May 8) suggests to 

 me to appeal to fellow-correspondents on the subject of useless 

 matter. The labour of merely reading — not to mention that the 

 judicial faculty is to be kept constantly on the stretch — all that 

 comes to a weekly journal is, of itself, so great, that if I had to 

 choose between it and penal servitude, or the workhouse, I am not 

 sure I would not prefer either to it. Why, then, tax still further 

 already faculties suificientlj- burdened, when what is written is quite 

 out of place ? If a man has a grievance connected with the Queen's 



Bench, would he write to the Archbishop of Canterbury for 

 redress ? 



K.nowi.eih;e is a scientific journal, and when we write to it wo 

 should leave our religious ojiinions at the door, as wo do our sticks 

 and umbrellas when wo visit an exhibition. Hy confiding to the 

 attendant things useless — possibly dangerous — when wo are going, 

 we in no wise show ourselves ashamed of thorn, or renounce re- 

 sumption of them. 



Every sane mind may be compared to the equilateral triangle 

 inscribed in Euclid, i., 1, between the two intersecting circles, which 

 are knowledge and faith — i.e., all men are guided («) by what they 

 know ; {h) by what they believe ; which science has not taught 

 them, and cannot despoil them of. E.g.f Mr. Bradlaugh has a j)ro- 

 nounced religious belief, which is that there is no (iod. He cannot 

 prove this, but it is his belief. 



On the other hand, while stoutly upholding that no postulate, in 

 science, must be made from unprovable belief, I cannot help think- 

 ing that (a) Knowledge has sometimes expressed opinions on 

 religious topics which (by rule) should have been lot alone ; (6) 

 that matter has been excluded as theological when it was purely 

 scientific. A discussion on the jthilosnjMcal and j>/i i/sical bearings 

 of, say, Transubstantiation, seems to me ])erfectly within the scope 

 of K.vowledge. E.ij., 1 suggested lately, that if the molecules of 

 ultra-gas have little or no attraction for each other, if single stars 

 are in the same predicament, does it not look as if the universe 

 was a gas, the stars the molecules ? If so, u-hat is the gas ? The 

 Pantheists hold that nature is the body of God, so to speak, that 

 all is God. Well, I may be fanciful in thinking that the knowledge 

 of the gaseous state is a step towards Pantheistic doctrine. But 

 you. Sir, exorcised this as trenching on theology. How, I cannot 

 see, since Pantheism is banned as droatUuI lioresy and blasphemy. 



I am sure that, if Plato had been editor of an .\thenian ft m'sis, 

 he would have taken up this speculation, so like many ho has left 

 us, and I think the editor of Knowledge need not be .ashamed of 

 what Plato would have approved. Knowledge should treat de 

 omni scihili. Hallyauds. 



L" There is," according to the old proverb, " many a true word 

 spoken in jest," and really what " Uallyards" says in his exordium 

 with reference to the mere physical labour involved in dealing with 

 the huge and heterogeneous mass of correspondence which weekly 

 reaches a journal like Knowledge, contains but little exaggeration. 

 But I can scarcely go with him in his ideas as to the scope of such 

 a serial as this, the avowed object of which is to expound the 

 leading facts of science, natural and physical, in plain and appre- 

 hensible language. Now, I may be right or I may be wrong, but 

 Transubstantiation appears to me to be a subject which is in no 

 sense amenable to this treatment. It 'is a dogma of a particular 

 sect of theologians, and to initiate a discussion into its nature — 

 and even into its possibility — would be to open the door to a good 

 deal that can in no sense, and by no conceivable perversion of lan- 

 guage could, be called Science at all. I am not concerned to deny 

 that, had Plato, as " Hallyards " says, edited an Athenian " Vvioa.g," 

 he would have discussed such questions as those to which our 

 correspondent adverts, keenly in its columns ; but what appealed to 

 the sophists and dialecticians of Athens more than 2,300 years ago 

 may not, after all, be the most suitable intellectual food for English- 

 men, who, towards the close of the nineteenth century, take in a 

 popular magazine to learn something of the current science of the 

 day. — Ed.] 



LETTERS RECEIVED AND SHORT ANSWERS. 



HiBERNicus wishes to point out that the words "conducting war 

 on Christian principles " which appear on p. 370, in a review of 

 " Essays on Economical Subjects," are the reviewer's own, and are 

 not a quotation from his book. — Lieut. -Col. Campbell strongly 

 recommends the " Rudimentary Treatise on the Integral Calculus " 

 bj- Homersham Cox, published in " Weale's Series," as at once very 

 cheap and excellent. — Dr. Levvins. Your letter of the 11th inst. 

 merely reiterates, with slight variations, the arguments employed 

 in the one which appears on p. 421. — G. Humfress. No, all your 

 experiment proves is that the lens showing colour was cut parallel 

 to the axis of the quartz crystal. The one which exhibits no bands 

 may also be a " pebl)Ie" lens properly cut — i.e., accurately at right 

 angles to the crystal's axis. Of course, it may be ordinary glass, 

 but this is very unlikely. The test you applied will not solve 

 this point. Get a broken bit of felspar (the greyish, and often 

 reddish, constituent of granite), and try to make a minute 

 scratch close to the edge of your lens. If the felspar 

 fails to touch it, it is quartz. — Senex. Just as you please. 

 An ephemeron and a raven bom on different days, then, 

 but co-existing. Pray read the article " Nebular Hypothesis," in 

 Nichol's " Cyclopaedia of the Physical Sciences." The expression 



