Nov. 3, 1882.] 



KNOWLEDGE 



379 



for the " glaring mistakes" in our essay on "A Menacing 

 Comet," we should be obliged if Mr. Oliver would point 

 out what they are. We apprehtnd he mistakes the mis- 

 takes we corrected, for mistakes we had made. We see 

 nothing in the essay to correct ; when we do we shall 

 say so ' 



A Mysterious Will. — James Beatley, of Huntingdon, 

 L.I., has a well on his premises that is both a curiosity and 

 a puzzle. The well is twenty -three feet deep, and is dry 

 every year from Jan. 1 to the first week in March, as 

 regular as the days of the year. It will be as full the day 

 before it dries up as at any time during the year, and on 

 the following morning not a drop of water is to be seen 

 where a depth of three or four feet existed before. About 

 the first week in March the well fills again in a few 

 moments, and the water remains for the remainder of the 

 year. 



Professok Tyndall on De. Siemens' Solar Theory. 

 — It would give me extreme pleasure to be able to point 

 to my researches in confirmation of the solary theory 

 recently enunciated by my friend the President of the 

 British Association. But though the experiments which 

 I have made on the decomposition of vapours by light 

 might be numbered by the thousand, I have, to my regret, 

 encountered no fact which proves that free aqueous vapour 

 is decomposed by the solar rays, or that the sun is re- 

 heated by the combination of gases, in the severance 

 of which it had previously sacrificed its heat."- — Loiiy man's 

 Alayaziiie. 



Coal in British India. — Coal of good quality for 

 locomotive purposes is systematically worked in the Bengal 

 coalfields, which extend for about 100 miles to the west of 

 Burdwan. Collieries exist also at Wahrora and Mohpani, 

 in the central provinces. A very valuable coalfield is 

 known to exist at Makuni, in Upper Assam, which will 

 doubtless be opened out when the Assam Light Railway 

 is completed. The total output of Indian coal in 1880 

 was 1,016,040 tons, of which by far the greater amount 

 was raised in the Ilaneegiinge coalfield. Madras finds it 

 cheaper to use patent fuel from England than to depend 

 upon Indian coal brought from long distances by land. The 

 total quantity of English coal, coke, and patent fuel im- 

 ported into India during 1880-81 was 68.3,768 tons, 

 valued at £1,239,805. 



An Electric Tricycle. — The improvements in the 

 storage of electric energy and in electro-motors have so 

 far advanced that tricycles can be lighted and propelled by 

 electricity, as was seen from the tricycle ridden last week 

 by Professor Ayrton in the City. The Faure accumulators 

 in which the energy was stored for the lighting and 

 driving were placed on the footboard of the tricycle, and 

 the motion was produced by one of Professors Ayrton 

 and Perry's newly patented electro-motors, placed under 

 the seat of the rider. Using one of these specially 

 made tricycle electromotors and the newest type of tlie 

 Faure accumulators, the total dead weight to be added to 

 a tricycle to light and propel it electrically is only IJ cwt, 

 a little more than that of one additional person. In the 

 tricycle ridden by Professor Ayrton the ordinary foot 

 treadles were entirely absent, but with ordinary electric 

 tricycles it may be desirable to leave the treadles, so that 

 while electric propulsion alone is used on the level, the 

 rider can, on going up a steep hill, supplement it by using 

 the treadles, instead of, as at present with the ordinary 

 non-electric tricycle, having t ) git out and ignominiously 

 push his tricycle up the hill before him. 



intrrs to tbc (Eliitor* 



[Thr ]'.''' r ,'.' ■ > nthold himselj'rei'ponsille/orthe cpiniona of hit ccrrftpondtnh. 

 17' ■ ' ' - /u relum mauuacripta or to corrtrpojid vrith their vrtttra. Ail 



(-r, '/ he aiighortu$postible,conaiittntiyKithfullattdcltarftate- 



J 1 '] , ,-;,,- „.i,},icuiiciis thoiild le addreited to thr Idilor of KHOWIMCB : 

 afl Bi,>iu,.i!. ctmmuniiutioiia to the Pulliihirt, at the Office, 74, Great Quctn- 

 'treit, W.C. 



All Semiltancei, Chequei, and Fatl-O^ce Orders ihculd le made payable t» 

 Meters. Witinan ^ Sot'S. 



',' All letters to the Editor kxU le Kumlered. For conrenitnce of reftrevce, 

 oorretpondeuts, Khen r^errivg to anij letter, will oblige by meniiojtintj its iivv.le^ 

 and the page on tchich it appears. 



" In knowledge, that man only is to be contemned and despised who is not in ft 



state of transitioi- Nor is there anything more adver&e to accurB*y 



than fixity of opinion."— J'f^rfliffly. 



" Show'me a man who makes no mistakes, and I -Kill show you a man who has 

 done nothing." — Liebig. 



HAS THE MOON AN ATMOSPHERE ? 



[614] — TLis question has been a debatable one with astronomers, 

 though generally answered in the negative ; there, however, seems 

 to be, from what Mr. Banyard has to say upon this subject in his 

 paper on pp. 215-246 of this volume, every probability that the 

 question as to the existence of a lunar atmosphere will soon be 

 definitely settled. At the conclusion of the highly-interesting paper 

 above referred to, Mr. Eaynard makes a few remarks upon a 

 curious phenomenon to be seen at the time of the new moon, viz., 

 a faint line of light round the dark limb of the moon ; and requests 

 observers to take notice of it, and send the results of their obser- 

 vations to Kkowiedge. Unfortunately, since the publication of 

 Mr. Eanyard's paper, cloudj- -sveather has prevented me observiuic 

 the moon when sufficiently near conjunction ; and as I think thi.s 

 phenomenon, if carefully observed, is likely to throw some light 

 upon the question heading this letter, I venture to call attention to 

 it, because in a climate like ours it is necessary that there should 

 be several observers, as it often happens that one observer will see 

 some phenomenon that an observer at another place is unable to 

 ob.«erve on account of bad weather. 



In his paper, Mr. Eanyard suggests that this "line of faint 

 illumination " may possibly be due, either to " a dispersion of tho 

 sun's rays within an atmosphere," or else " caused by a phos- 

 phorescent light from the lunar surface." With regard to the fiist 

 of these suggestions, 1 would like to ask whether an atmosphere of 

 sufficient density to make itself visible as a "line of light" would 

 not have some effect upon the occultatious of stars ? Eespecting 

 the latter suggestion, I should like to know whether any observer 

 has noticed the " line of faint illumination" along the dark limb 

 of the morniug moon ? B. J. HorKi.\s. 



[After what Zijllncr's photometric observations have proved (to 

 all intents) as to the average slope of lunar mountains, it is 

 tolerably clear that that arc of light should be seen — whether 

 moon has appreciable atmosphere or not. — El>.] 



ANCIENT MONUMENTS. 



[615] — In the Government list of ancient monuments to be pitj- 

 tected (in No. 47, Sept. 22), 1 am soitv to observe that one 

 interesting relic is omitted. It is a cromlech called Arthur's 

 stone, in Ilortfordsliire, about 15 miles W. of Hereford, on the 

 ridge that bounds tho Golden Valley (Valley of the Dwr), to tho 

 N.E., and close to tho picturesque little village of Dorston (Dwr'.^ 

 town, or the town on the Uorc). Originally it was covered with 

 stones and earth, forming a mound, and is situated where a laiio 

 crosses an ancient liritish road that ran along the ridge, and is 

 crossed farther south by a Eouian road that led to Abbey Doro. It 

 consists, like Kit's Coity House, of a stone supported by several 

 others, but the supporters are more numerous, and smaller, and tho 

 top stono much larger than at K. C. H. There is to the N.E. of 

 this ivlic about 100 yards, just as at K. C. H., another largo stone 

 lying doH-n. There is a lino view from this spot of the whole 

 Uolden Valley, with its Norman castles, its Abbey, and ancient 

 tumuli of tho Black Mountains, that separate Herefordshire from 

 Brecknock, and in tho extreme S.W., the Great Skirrid, Horned, or 

 Holy Mount. A lino drawn thiough tho long astis of the top stono 

 if ekteuded would just touch the Skirrid. J. E. S. 



