Dec. 1, 1882. 



♦ KNOWLEDGE ♦ 



439 



to have a -bluer tinge in it than given off when a vessel drives 

 throngli the water. With regard to the depth to which this phos- 

 phorescence occnrred, I believe that it was confined to the surface 

 in this case, because when I dipped a lead line some 8 or 10 in. 

 below the surface I failed to make out the lead. At the time 

 several dolphins were swimming about, and I noticed that at what- 

 ever point one of these fish made its appearance, the inky dark- 

 ness contrasted strangely with the illuminated portion of the sea. 

 At midnight the glare gradually decreased, and about one o'clock 

 had entirely disappeared. A stiff breeze sprung up within a few 

 minutes, and our good ship bowled along at the rate of nine knots 

 the hour. When off Cape Horn I again saw a portion of the sea 

 illuminated, but the effect was nothing like my former experience 

 in grandeur. However, it did us one good turn by showing the 

 approach of a large iceberg. Eessorp. 



STORM IN A PICKLE-JAE. 

 [649] — I have lately kept in my room a homely sort of weather- 

 glass, consisting of an oil fiask turned neck downwards in a glass 

 pickle-jar nearly full of water. It is not a very accurate instru- 

 ment, but interesting observations may be made with it. For 

 instance, the warmth of a finger and thumb on the bowl of the 

 flask in a few seconds causes the air within to expand sufficiently to 

 drive the intruding water further down the neck. It is also more 

 sensitive to slight variations in the weight of the atmosphere than 

 far more expensive instruments. During the storms of wind on 

 Nov. 1 and 3, the barometer fell, and almost all the water was 

 driven out of the neck of the flask, but not without a very per- 

 ceptible struggle ; and it was most interesting to watch the storm 

 reproduced in almost incessant movements in the narrow neck ; 

 and before the storm outside seemed to abate at all the pickle-jar 

 told me that the worst was over, and the water, still straggling, 

 began to rise towards its old position. A. M. F. 



DEATH-WARNING. 



[650] — A friend of mine (Dr. GoodaU Jones, of Liverpool) 

 related to me the following account of a case of premonition, which 

 I thought might prove interesting, as it is well authenticated. The 

 names and dates Dr. Jones will give if required. 



He called on a female patient on Sunday afternoon at three 

 o'clock ; her husband met him at the door, and said that he was 

 about to come for him, as the patient was worse and delirious. On 

 going upstairs the doctor found the poor woman in a very excited 

 state, asserting that her brother (a Liverpool pilot) was drowning 

 in the river, "which," said the husband, "is impossible, as he is 

 out at sea, to the best of our knowledge." The doctor did what he 

 could to soothe his patient, and left convinced that it was a case of 

 ordinary delirium ; but in the next morning's paper he read with 

 surprise the account of the pilot's death by drowning in the river 

 on the previous afternoon at three o'cloci;. J. Sinclair. 



A PHENOMENON. 



[651] — When in Switzerland last year, in September, in the 

 morning, about 10 o'clock, we saw a beautiful and curious pheno- 

 menon, audi should be glad to know if it is common, and its causes. 

 We were en route from Interlaken to Berne, standing on the deck 

 of a steamer at Darligcn, waiting for it to start. Above us, to the 

 south or south-east, rose a steep, abrupt hill to a great height, and 

 at the top it was fringed with firs, which stood out like verj' small 

 Christmas trees, dark green against the sky. In one spot, how- 

 ever, these trees were of a bright, transparent silver, as if turned 

 into crystal, and among and above them there glided, erratically 

 and in all directions, apparently four or five small bright stars 

 (about the size of third or second magnitude stars). These 

 larger stars were plainly visible to the naked eye, but with 

 my glasses I could make out that in this one spot the 

 air was one glinting, glittering mass of tiny bright specks, all 

 moving in every direction. We called the attention of the pas- 

 sengers to it, and many were the conji of ures as to what these 

 appearances were, and why ;' ■ v, ■ S. nie said birds, others 



falling snow, but no one gavi' : i \nlaiiation. 



I should add that wo wi r- ; tliat the sun was jtist, 



and only just behind and lulcw ;) ii i _ I sky-line, as we found on 

 starting; that it was a bright day .iiicl cliar; and that somehow 

 the sun must be the cause of the phenomenon, for directly we 

 moved off he appeared, the little stars disappeared, and the 

 transparent fir trees returned to their natural dark green. N. R. 



[Most probably the firs covered with ice-crystals, and the ice- 

 crystals which active air-currents carried round and above the 

 firs, were just in that position (about 22° from the sun) at which 

 the arc of a solar halo would be formed. — Ed.] 



ansfturrsi to Coriesponlientsf* 



HnriS TO CoBEBSPOirDISIS.— 1. A'o qatsliont atlciva /or tnmlific iK/ormalto* 

 an be anmered through the poll. 2 letter, lent to the Editor for eorreipondentt 

 annotbeforxarded, nor can the namei or addreiiei of correipovdenli be given in 

 niver to private irtquiriei. 3. Corretpondenti thould rrite on one ride ohiy of M« 

 aper, and put draicings on a separate leaf. i. Eaih letter ihould hate t 

 < replying to a letter, reference should be made to ill number, the page i 

 ppeari, and iti title. 



rhich it 



R. B. W., SUBSCRIBEE (2), S. D., Tnos. Thomas, Remex, G. H. A., 

 DisciPULUS, and many others. I will at an early time give a brief 

 account of the Hamiltonian method and of my experiences with it. 

 Gr-AVITY. Tour mistake lies in taking no account of the 

 increase of your namesake as the sun is approached. — Astro- 

 nomical JrMBO. Your question could not possibly be an- 

 swered in Knowledge. It is a long and arduous matter to 

 explain the calculation for determining a comet's orbit from 

 three observations.— Parallax. Find the right ascension and 

 declination corresponding to the altitude and azimuth. Ton can 

 then at once determine the longitude and latitude of a point on the 

 earth having that star at its zenith. We cannot undertake to solve 

 such problems as are dealt with in every book on practical as- 

 tronomy.— T. H. D. Sculling is as bad as rowing for the chest, 

 unless corrected bv other exercises. The picture of an American 

 oarsman represents a sculler.— L. Orme. Tail at least a hundred 

 million miles long; least possible distance from earth rather a 

 troublesome matter to calculate, and of no great interest, as the 

 comet can nowhere approach the earth mthin many millions of 

 miles — W B. Thanks ; the illustration is absurd, of course, but 

 near enough for Times' science.— M. H. C. You will find that the 

 mistake about tangential force was corrected by myself at the 

 earliest opportunity. See foot-note, p. 300. It was a printer s 

 error. About Newcomb, I have forgotten what you said ; but I 

 know that what I described as erroneous he himself admitted to 

 be so. As regards Dr. Siemens's theory, it would not much 

 matter, I suppose, whether one particular objection failed, if 

 another held. If one link breaks, proving another sound does 

 little good. But I hold you mistaken as to the difference between 

 the effects where solar atmosphere is limited and where it is .as- 

 sumed to be unlimited. As to cloud-bands, n-hat is it you assert ? Do 

 von sav that straight bands never seem arched :— H'sett. Though 

 1 do liot publish vour letter, I thoroughly agree with yon. The 

 account you refer to is in a scientific sense utterly inadmissible.— 

 H. K. L. It has never happened to me to want to know about 

 degrees of freedom : perhaps some reader can tell where to find this 

 mathematical expression explained.— J. Sme.\tox. Thousands have 

 entertained that theorv about comets' tails ; but it will not stand 

 inquin-.— J. Sllmixgtox? Penxiw.4Ttor ? J. Slexeriwijter (?). Ao, 

 a cannon-ball does not rise after leaving the mouth of a horizontal 

 cannon.- J. P.\rry. It pains me to have to say that the comet as 

 thus far observed travels not only on the Sabbath-day (which I 

 take to be Saturdav), but also on Sunday. But you must not 

 desert it on that account ; or, if vou do, then to be consistent yeu 

 should desert the earth .ilso ; for she does, too : aye, and moreover 

 rotates, and reels, and nutates, and accompanies the sun on his 

 cosmical rush through space.— S. Spencer wants name of best 

 manual on the Metallurgv of Gold, and methods of seeking mining, 

 ic— S. E. C* We hard"lv differ so much as you seem to think. I 

 quite think that, speaking" logically and reasonably, the views of a 

 man like Darwin about religion, a future life, ic, may be of great 

 interest. (So a pound out of his pocket would be worth twenty 

 shillinffs, if he chose to give it.) But you know that there are 

 many who are prepared to howl if they learn that you do not hold 

 the same \-iews as thcv do on certain religious questions. Now, 

 manv prefer not to be" howled at, and therefore keep their views 

 on such matters to themselves. To ask such a one privately what 

 his views are is all right enough, especially if he happens to be a 

 personal friend. (Just as it is quite legitimate to ask a man for 

 a pound for some charitv.) But to regard his reply as something 

 which mav bo proclaimed on the house-tops is altogether wrong. 

 If vou want to know what may be done in the way of howling, read 

 some of the comments of certain religious papers on tha letter, 

 which should never have been published.— X. Impossible to say 

 without seeing the specimens ; and wo cannot make arrangments 

 for the forwai-ding of such things. Dr. Ball was mistaken about 

 the height of the tides in those remote times.— J. Battle The 

 maps for November and December will be the same m shape and 

 character as the rest ; they will also bo published separately, price 

 2d. each.— A. H. Lee. Fear long time must elapse before the pres- 

 sure of other subjects so far subsides that papers on philologj- can 

 appear.— F. Y. (I). The tail of a comet is a variable appendage; 

 most probablv the tail of one week is quite different from the tail 

 of the next week ; (2) the comet of 1843 was seen from the earth 



