January 2, 1893.] 



KNOWLEDGE. 



AN ILLUSTRATED 



MAGAZINE OF SCIENCE 



SIMPLY WORDED— EXACTLY DESCRIBED 



LONDON: JAM AHY .V, 189;^. 



CONTENTS. 



The Disaster at St. Gervais. (A Sii|iiiU'iiK-nf.) By tlu' 



Tii-lit II, .11. Siv KiiwARii F»y. 1.1..1> . F.K.S. &.• 



A Volatile Series of Metallic Compounds. l!y C. F. 



TowNsKMi, F.C'.S. 



Caterpillars— Til. By E. X. Butler 



The Number and Distance of the Visible Stars. I!\ 



.1 Iv (.i.MiK, F.E.A.S 



Science Notes ■■ 



What is a Nebula? Hy -\. C. Ranyakp ... 



The late W. Mattieu Williams 



Notices of Books 



Letters :- G. W. Grabham, il.D. (LoikI.)i.T. Ewkn Davidson ; 



W. T. Ltnx ; Dr. A. Beester, Jz 



Lemurs By E. 1 tdekkee, B.A.Cantab. 



The Face of the Sky for January. By Herbert 



Sadler, F.R.A.S 



Chess Column. By C. D. Locock, B.A.Oxon. 



9 

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 12 

 12 



13 



14 



18 

 19 



THE DISASTER AT ST. GERVAIS. 



A Supplement. 

 By the Right Hou. Sir Edwabd Fry, LL.D., F.K.S., Ac. 



THE article wliicb appeared on this subject iu the 

 November number of Knowledge has brought me 

 some letters which appear to me well worthy of 

 the attention of my readers, and with the per- 

 mission of their writers, and with some slight 

 alterations and additions kindly made by their hands, they 

 appear below. 



I am desirous also of availing myself of this opportunity 

 to make a few additions and corrections to my article. 



First, I may mention that three papers on the subject 

 have appeared in the Comiitcs Ficmhis : one by M. Forel, in 

 the number of the 18th -July, 1H02 (p. 103), another by 

 MM. Vallot and Delebecque on the '2.'jth .July, 1.S02 

 (p. 2(M), and the third by M. Demontzey on the 8tli 

 August, 1892 (p. 305). The last paper mentions the fact 

 that some workmen saw the moving mass from a distance 

 in the clear moonlight, and they gave live minutes as the 

 time it occupied in passing from the gorge of St. Gervais 

 to Le Fayet, a distance of 1800 metres, or at the rate of six 

 metres a second. The writer also mentions the fact that 

 the passage of the torrent has stripped the beds of the 

 streams of Bionnassay and the Bon Nant of all the granite 



blocks which for long have been found there, and that the 

 torrent when entering the Bon Nant at Bionnassay first 

 drove right across the stream, and deposited materials of 

 all sorts on the left bank at a considerable height. 



Referring to what I said on p. 203, second colunm, as to 

 the moving power of water, I think that it should be 

 observed that the moving mass was by no means pure 

 water, it was water, ice and mud, and I apprehend that the 

 ino\nng force of such a mass (which as a whole must be 

 somewhat viscous) differs from that of pure water or any 

 other true liquid. 



Fig. 7 is so drawn as to represent the height of tlie 

 water in the two communicating cavities as different. 

 This is, of course, impossible, and I must ask my readers 

 to make the necessary mental correction. 



The following are the letters above referred to : — 



h'rom tlw Hon. Mr. .Justice Wills. 



The acciiniulatioii of such ii raas.s of water at such a height is a 

 very remarkable fact. I have once or twice seen cavities in the 

 neve on a scale comparable with that on which the two holes in 

 question were, but only once or twice. One was a very remark^iblc case 

 indeed: on September l.")tli. 18.58, 1 was descending the glacier d'Oniy 

 with a friend and two guides: we were still on the neve, and I noticed 

 a thing which looked like ii dark patch on the ice at a short distance 

 from us. I said I should like to go and see what it was. As I drew 

 nearer I saw it was a hole and I took the precaution of continuing in 

 the rope, which we had not yet taken off. On reaching the spot, I 

 went to the edge of the hole on my hands and knees and lay down to 

 look into it. As soon as my eyes got accustomed to the comparative 

 darkness into which I was gazing I saw to my horror that we were all 

 of us on the crown of an arch of ice which from side to side was, if 

 my recollection serves me, some 30 yards across, and which, at the 

 top and at the very spot on which I was lying, was not more than a foot 

 or 18 inches thicii. The chasm extended in length further than I 

 could see in either direction, but this was the only spot in which the 

 top had given way. It was of great depth, I should think 100 to 150 

 feet, and there were many places in which pendants <.f ice, 

 evidentlv formed by drip, were hanging from the roof ; others in 

 which lilocks that had had ice pendants hanging from them had 

 fallen into soft snow, or else merely got gently dislodged, for the ice 

 pendants were still unbroken and yet pointing in many directions. 

 It was a scene of really awful magnificence, and made a great 

 impression upon all of us. We had walked across the arch without a 

 suspicion of a hollow beneath, and yet the hollow was sufficient to 

 engulf an army : we saw no water there. 



I saw a thing of the same sort once on our own Buet, where the 

 glacier is on so small a sc:ilc that we never dream of being roped. I 

 saw a similar dark spot, went to look at it, found it was the top of an 

 arclied Oiivitv on a very infeinor scale to that on the glacier d'Orny, 

 but still calcidated to teach one respect and caution. I had a ball of 

 string witli me, and I tied my stick to the end of it and let it down 

 what proved to be S4 feet before it touched bottom. Here, again, 

 tliere was no water. 



Melting at 9000 feet in height is a totally different thing to 

 melting at 6000 or 7000 feet, and I have never seen a large crevasse 

 in the neve charged with water, nor do I remember to have read of 

 one. The highest of such that I ever remember to have had my 

 attention called to, was on the upper plateau of the glacier des 

 Bossons, perhajis 8000 feet or even more above the sea. We lost a 

 little dog who fell down the crevasse by jumping short, and we heard 

 him swimming quite out of sight. We let down a porter — fortunately 

 we were a strong party and could pull him up again — and he found 

 the dog on a ledge of ice at the edge of a deep pool. The de;id 

 weight of a big man to haul up again by main force was something I 

 shall never forget. The crevasse tvristed, and at one moment his 

 broad shoulders got jammed and I thought we should not get him 

 out again. But whatever height this was, it was far below the limits 

 (at that place) of the neve, and the ice had none of the character- 

 istics of the neve. 



There is, however, very likely more drainage on the glacier des 

 Tetes Rousses than on most glaciers of that height. I cannot say from 

 personal recollection, as the only time I crossed a part of the glacier 

 des Tetes Rousses, on an ascent of Mont Blanc by the Aiguille de 

 G-oute, my attention was not drawn to the point, but I think it very 

 likely that a part of the drainage from the Aiguille de Goute may fall 

 on to its side and get into its interstices. The Aiguille de Goute is 

 too steep for a permanent glacier to form on those ridges and furrows 

 which are so great a characteristic of its structure. Vast quantities 

 of snow fall and lodge upon these ridges and furrows, and melt very 



