Jamauv. lOlJ. 



KXfnVLl-.DGi:. 



,'enerally found that the gem-stones in the " native- diamond dust, and revolves horizontallv instead of 



cut " condition are unsuitahle for tlie re(]uirements 

 of liigh class European jewellery. It is therefore 

 necessary, hefore the\" can be used for the purpose, 

 that the\' shall he re-cut by a skilled lajiidarv with 

 a knowledge of mineralogy and optics. 



In principle, the apparatus used hv the Euro[)ean 

 gem-cutter is similar to that used by the Moor in 

 Cevlon. The wheel is, however, made of copper and 



perpendicuiari\- (see h'igure li). 



The operator sits at a bench and [)laces the gem, 

 mounted on a small ebony holder, against the surface 

 of tile wheel whicli he rotates b\' means of a crank 

 held in the left hand. .\lthough the apparatus is 

 simple, much expert knowledge, skill and experience 

 are re(|ui3ite for success in this delicate and artistic 

 craft. 



C()KK1-:SP0NDENCE. 



THE Nl-:En FOR TELESCOPES. 

 To flic Editors of " KNOWi.i:i)r.K." 



Sirs, — 1( is indeed strange, as Professor Hickcrton observes, 

 that .Astronomy lias not a greater hold on the human mind. 

 Hut perhaps the general public are not altogether to blame for 

 their neglect of that glorious science. Compare, for instance, 

 the facilities enjoyed by townspeople for literary study, with 

 the opportunities given them to use a good telescope in 

 conjunction with star maps and te.\t books. Where can the 

 " man in the street " go to feast his eyes on the clusters so 

 eloquently described by Professor Bickerton ? 



Years ago I was young and n.aive enough to ask if I might 

 go to Greenwich to look through the Observatory telescope. 

 I can well iniderstand that casual amateurs would interfere 

 with investigations at the great centres of ob.servation. Hut. 

 surely, reading rooms, libraries and village clubs here and there 

 might be provided in an upper floor with a 4'.-in. telescope, 

 imder the care of some responsible person in the neighbour- 

 hood, who would instruct an attendant. 



Wanted, then, a scientific Carnegie to provide telescopes. 



No doubt that the taste for star-gazing is growing, and that 

 the Daily Telegraph reflected general interest in publishing 

 monthly charts of the sky. 



Professor Bickerton's shepherds and. I would add, fishermen, 

 would appreciate, even more fully than they do. the beauty of 

 the heavens, when they learnt to identify groups in single stars, 

 and could follow their motions. I'heir educated friends should 

 pass on some elementary knowledge to simple people by the 

 only sure methods, namely, by pointing out constellations in 

 stars when opportunity offers, and especially drawing attention 

 to their changing positions as time goes on. , ,, ,, 



Waui;ham. 



mi:teors. 



To the Editors of " Knowledgi;." 



Sirs. — Will you allow me a little space in your valuable 

 paper in which to make an earnest appeal to all amateurs who 

 are iTiterosted in meteoric observations ? 



Too little regular work is done in England and. with the 

 successful example of Mr. Denning before us, we in this 

 country who are at all enthusiastic in the matter, might do 

 much work that would be \aluable if only we undertook to 

 systematically watch the sky and furnished full reports of our 

 seeings to someone qualified to investigate them. 



For many months past my husband and myself have 

 observed every fine evening at regular hours and sent in 

 frequent reports to Mr. Denning with whose results we have 

 had many interesting accordances. Unfortunately as he 

 i.^ not well now and his work limited, many of our observations 

 are of little use. as of course it is only by two observations of the 

 same meteors in different places, that any accurate knowledge 

 can be obtained of their real paths. Will some amateurs who 

 care about this branch of astronomy agree to watch regularly, 

 evening by evening, at stated times, and send us each week or 

 month their records, which we can then conipare with ours 

 and write out both together and send to .Mr. Denning or some 

 other authority. 



If two li,>urs or more are too long the time could be divided. 



and each observer have perhaps half an hour or so. we could 

 easily manage to arrange in a way suitable to everyone's 

 wishes. It is such interesting work 1 .All day long I look for- 

 ward to the silent hours when our watch begins, the stars 

 seem no longer far-away twinkling lights, but intimate friends, 

 and each moment is filled with the glow of anticipation as to 

 what grand meteor will next appear on the scene. 



In our observations we record the times, magnitudes. 

 Right .Ascension and Declination, of appearance and dis- 

 appearance, direction of flight, details of colour, train or 

 trail, and so on. If any of those who, after this appeal, 

 consent to watch, do not care to spend time in determining 

 the Right Ascensions and Declination, or the altitude or 

 azimuth, the name of the star where the meteor appeared to 

 come, and the one where it appeared to go to. will be quite 

 sufficient, if they will kindly mention the name of the star atlas 

 tliey use. as some of the smaller stars have dift'erent letters or 

 numbers in diflbrcnt maps, and it might be diflicult to trace 

 them. Mv.uldress is — Zavijava. Hansol Road. Hcxley Heath. 

 F1AMM1".TT.\ WILSON. 



TO FIND .VPPROXIMATELV SIDEREAL TIME. 

 To the Editors of "Knowlkdgf.." 



Sirs, — May I add a post-script to my letter of November 

 giving the eeiuation R..A. = h + 2 m + 5 as an approximate index 

 to Sidereal time ? 



.As a practical application of the equation I have marked 

 on my watch-dial +0 against IX, +6 against XII, and +12 

 against III to remind me that on 22nd September Sidereal 

 and clock time are the same, and that in December the dift'er- 

 ence is six hours, and in March 12 hours. 



LVXDHURST. FK1:D B. TAYLOR. 



IHrNDFRSroIvMS. 

 To the Editors of " Kn-owi.edgk." 

 Sirs. — I have been for a great number of years a very 

 careful observer of Thunderstorms and Electrical Phenomena 

 in this and other countries, and possibly some day I may 

 trouble you with a few of my notes. But I write now to put 

 a question to your readers which is perhaps more amusing 

 than scientific. Inasmuch as the world is round and thunder- 

 storms like everything else have a beginning, it follows that 

 the first flash of lightning in any storm must be directly over 

 somebody's head. How is it then that we cannot meet with 

 anyone who remembers anything of the sort ? We are in- 

 variably told that distant thunder was heard, or, if by night, 

 distant lightning was seen near the horizon, and the storm 

 gradually approached. The Times, in de.scribing a storm in 

 London, always begins in this wa> — " Heavy clouds were 

 observed in the West and a little later distant thunder was 

 heard, and at such and such a time the storm broke over 

 London." This, too, is the way local newspapers always 

 describe storms. Considering how common in the late spring 

 thunder showers are. it seems strange that wherever we are 

 they always make their first appearance in the distance. 



tanki:rville chambi:rlayni:. 



WiNCIIKSIl k. 



