Deo. 22, 1882.1 



. KNOW^LEDGE 



485 



letters to tfte dtiiitor* 



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" Let Knowledge grow from more to more." — Alfred Tennyson. 



THE TRANSIT OF VENUS— SATURN'S RING— BRAIN 

 TROUBLES. ■ 



[661] — If I am not transgressing the " unwritten law " of Know- 

 ledge by treating of three separate subjects in one letter, I should 

 like to saj- : — 



1. That I observed the Transit of Venus on December 6, from 

 2h. 27m. 21s. p.m., Maresfield Mean Time, until about half-an-honr 

 before sunset. I failed, of course, to see the first contacts, either 

 external or internal, as the latter was calculated to take place at 

 2h. 21m. 41s. at my observatory, and it was only at the time pre- 

 viously specified that the sleet ceased and the clouds broke suffi- 

 ciently for the sun to be glimpsed at all. What struck me most in 

 the view of the phenomenon which I had, was the apparently large 

 size of the planet, which resembled a jet black five-shilling piece on 

 the solar disc — the " milling " on the edge, by-the-by, being fairly 

 represented by the rippling due to our own atmosphere. Venus 

 was, as far as I could see, absolutely circular, no sign of ellipticity 

 being visible in her disc. Moreover, with the utmost attention, I 

 could detect no trace of an atmosphere around the planet 

 the solar photosphere appearing homogeneous up to his very 

 limb. The interposition of a plantation compelled me, after 

 ■3 o'clock, to exchange my 42-inch equatorial for a 3-inch telescope, 

 and with this my wife noted a reddish shading round the cii-cular 

 outline of Venus ; as, in fact, I fancied I did myself. I am a little 

 afraid, though, that want of achromatism may have had something 

 to do with tliig, as the effect was invisible in the larger (and abso- 

 lutely perfect) instrument. It was very odd to notice that refrac- 

 tion converted the circular outline of Venus into a markedly 

 elongated ellipse as the sun approached the horizon ; an instructive 

 illustration of its action at small altitudes, inasmuch as the diameter 

 of Venus was only 62"8, and her lower limb must have been 

 (apparently) considerably more raised than her upper one for her 

 to have assumed the figure she did. 



2. While thanking Mr. Herbert Rix for the really valuable in- 

 formation contained in letter 056 (p. 471), I must ask him to 

 forgive me for pointing out that the "mistaken assumption" to 

 which ho refers was not really mine, but that of the late Mr. Breen 

 (" Planetary Worlds," p. 217). I may, perhaps, note here, too, that 

 Cliambers (following Hind) calls the place of residence of tho 

 Brothers Ball, " Miuehcad, but curiously locates it in Somer- 

 setshire. 



3. The description of an odd brain trouble wliich I experienced 

 some two or three years ago may not bo without interest as a supi)lo- 

 ment to letter 057. I had been hard at work taking out some 

 hundreds of logarithms for the formation of a table of constants for 

 the reduction of my Transit observations; and, my work over, I 

 found myself continually making the extraordinary mistake of 

 transposing the last two figures of any series 1 was writing down 

 in a hurry. For example, for 94,02.3, I would write 91,032; for 

 £8. 68. 3d., £8. 33. Od. ; for 187!>, 1897; and so on. A short 

 abstinence from calculations, though, set all this right again. [This 

 curious mistake is very common among bank clerks, inasniuch that 

 when the balance for tho day is wrong by such an amount as 

 28. 9d., the more ingenious would set to work to ascertain by what 

 transposition of the kind the error may have been produced, often 

 thus getting tho balance right. It is to bo noted, however (tliough 

 this has no bearing on Captain Noble's remark), that such a 



difference may be given in several ways. Thus 2s. 9d. is Uie 

 difference between 4s. Id. and Is. 4d.; between Ss. 2d. and 2s. 6d. ; 

 Os. 3d. and 3s. Od. ; and so forth. Note further, that m every such 

 case, the sum of the numbers of sliillings and pence is always 

 tlcven. This may be easily shown. For, let a sum of a shUhngs 

 (. ponce bo written by mistake as b shillings a pence. Suppose a 

 greater than b, then tho error is (a-b) shiUings-H (b-a) pence- 

 (a-b-1) shillings -h (12- a -Hb) pence (for b-a bcingnegative, we 

 must, to give as usual a positive number of pence, add 12) ; so that 

 the sum of the numbers of shillings and ijence = (a - b - 1) + 

 (12-a + b)=ll.— R. P.] WiLtu.M Noble. 



light be tried by 

 It. Take a clear 



BRILLIANT METEOR. 



[602]— On the evening of Wednesday, the 29th ult., about 11.30, 

 a very brilliant meteor was seen in the neighbourhood of Auchter- 

 arder, N.B. It went in a northerly direction, and came very low 

 down before it went out; it lighted up the whole district so clearly 

 that the minutest objects could be seen. During its flight it 

 dropped fire something like a piece of iron when taken out of the 

 furnace at a white welding heat ; it continued to drop fire in this 

 way until it went out, and then, in about a minnte or so afterwards, 

 a sound was heard like distant thunder, which lasted for a short 

 time ; the sky at the time was clear and the stars shining brightly. 

 The meteor was a most brilUant one ; the sight of the balls of fare 

 constantly dropping from it was very grand. 



Would the sound like thunder be the meteor exploding, or would 

 it be a series of explosions which caused the fire to fall from it and 

 make the sound ? K- ^^ 



[More probably, I think, the effect of tho atmospheric dis- 

 turbance.— B. A. P.] 



A BOTTLE TRICK. 

 [663] — The following interesting experiment 

 some of your young friends when at the sea-co 

 quart bottle, and attach it at the neck, about two feet from the end 

 of a deep-sea fishing-line, which must not be shorter than thirty 

 fathoms. The lead sinker should bo sufficient to submerge tho 

 bottle while empty. Let the bottle be well corked, the cork being 

 of the same thickness throughout, and marked distinctly at tho 

 upper end. Sink it thus emptv from a boat, in about thirty fathoms 

 of water, and let it remain 'at the bottom ten minutes or more. 

 ■ffhen hauled up, the bottle will be found nearly full of water, and 

 the cork reversed. R. Montgomerie. 



RAINBAND SPECTROSCOPY. 

 [664]— As you im-ited the readers of Knowledge to send you 

 their experience of the rainband spectroscope, I am now sending 

 you mine, in case you think it worth insertion. I may remark, in 

 passing, that I have pleasure in confirming what Mr. Cory has 

 written in Knowledge, Nov. 3, 1882. 



1. When a band appears in the "red," small rain may be expected, 

 the intensity and duration of which will depend on the strength 

 and number of tho bands. 



2. If tho sun-lines in the "green," instead of appeanng clear 

 and distinct, appear thick and muddy, heavy rain (like thunder 

 rain) will follow, and this whether there is any ramband in the 

 " red" or not. „ 



3. If on moving the spectroscope slightly to the left the blue 

 appears very light and the daik line down is clearly seen, then 

 wind may be expected. I may say that this never fails. 



4. One day, on looking through, 'l noticed, on moving the spectro- 

 scope slightlv to the left as above, a peculiar appearance about the 

 green and blue. The ercen, instead of giving way to the blue, 

 scorned to fight with it and pass over it. Later in the day a 

 thunilerstorra followed. Twice since I have noticed this sign and 

 predicted a thunderstorm, which occurred each time. 



I have had my spectroscope since the beginning of June, and am 

 indebted to Mr. Rand Cnpron's pamphlet. " A Plea for the Rain- 

 band," for learning how to use it ; and I have, as a rule, adopted 

 his plan of looking with the rod colour on the left. 



Liverpool, Nov. 10. 



J. A. Bramley-Moobe. 



THE HAMILTONIAN SYSTEM. 



[■(3fi5]_For the information of your readers, may wo say that 

 the Hainiltonian system has not fallen out of print. It has been 

 published by us at the subjoined address for tho last ton years, has 

 been kept iii stock for manv vcai-s, and supplied by Messrs. Simpkin, 

 Marshall. A Co.. of StatioiiVrs' Hall-court, and Messrs. Hamilton A 

 Co , of Pnternoster-now, the two largest retail publishers of tho 

 trade, and can be had of anv of the school-book houses in London. 

 C. F. Hodgson. 



Gough-square, Fleet-street, E.C, Dec. 18. 



