Dr. Du Riche Preller—The Merjelen Lake. I 99 



the two basins were again united ; and by the 20th of September the 

 1 ike had risen farther 2 - 5 metres (8 feet), when along the glacier 

 wall there appeared a distinctly marked water-line, which afforded 

 unmistakable proof that the lake-level was again beginning to drop. 

 On that day it fell lOcentim. (4 inches); on September 21st, 

 30centim. (12 inches) ; on the 22nd the fall was 2 metres (66 feet) ; 

 on the 23rd the total fall reached 6 metres (20 feet) ; and daring the 

 night the lake emptied itself so completely that on the following 

 morning the glacier wall was exposed to view to its full depth of 

 about 50 metres (165 feet), and exhibited a large number of ice- 

 caves and perpendicalar fluted fissures, while the bottom of the lake 

 was strewed with blocks of ice which, as is characteristic of the 

 Merjelen lake, had been floating on its sarface, or had recently 

 fallen, and were still falling, from the undermined, and therefore 

 overhanging, roof of the glacier projecting into the lake. The 

 spectacle of the stranded ami still falling masses of ice, but more 

 especially that of the ice-cliff exposed in all its freshness, is one of 

 exceeding grandeur, although this freshness completely disappears 

 after a few days owing to the action of the air. 



On comparing this occurrence with the one of July 19th, 1878 — 

 the only one of which detailed record exists 1 — the writer finds that 

 on the latter occasion the lake-level began to drop in the morning of 

 July 18th, the drop being only one metre (about three feet) during 



Great 



Alelsch 



Ctacxcr 



1 

 60, OOO 



Merjelen Lata Glacier 



that day, further 3 metres (10 feet) during the night, and 40 metres 

 (130 feet), or practically to the bottom, during the day of the 19th 

 July. On both occasions, the phenomenon, therefore, occurred 

 under very similar conditions, the only difference being that in 1878 

 the initial drop took about twenty-four, and in 1895 about 48 hours, 

 whilst the time within which the lake emptied itself did, in both 

 cases, not exceed twelve hours. The bulk of the water thus 

 abstracted from the lake, after finding its way through fissures in 

 the glacier, discharges by the Aletsch glacier stream called the Massa 

 torrent, into the Rhone near Naters, about 2'5 kilometres (1*5 mile) 

 above Brieg. The occurrence of 1878 caused the Rhone at Brieg to 

 rise about 1-5 metre (5 feet) above its, then fortunately, low level. 



1 A short notice of this occurrence is given hy F. v. Salis in the Jahrhuch of 

 the Swiss Alpine Club, 1878 to 1879. Prof. T. G. Bonney ("Nature," 1867, x'xxvi, 

 p. 612) in August, 18.58, also saw the lake full one day and empty the next, the 

 emptying having taken place during the night. On the other hand, in 1890, 

 according to Prince Ronald Bonaparte, the emptying of the lake did not take place 

 till five days after the initial fall ("Archives de Genive," xxiv, 1890, p. 401). 



