RAPPORT OP M. CDLMANN. 89 



the great extent of that lake, — ^having traversed a course of 18 leagues, or 

 upwards of 50 miles, through Switzerland, in six hours and Orhalf, by a 

 movement gradually retarded. 



" ' AU the bridges having been carried away, the inhabitants on the two 

 sides of the Drause could have no communication for some days, or inform 

 one another of their respective losses, but by throwing across the river 

 notes attached to stones ; and the putrifying slime threatened them with 

 an epidemic. It is somewhat remarkable that an old man of ninety-two 

 saved himself by getting on a hillock supposed to have been formed by a 

 d6bacle in ancient times ; the new one followed him to the very summit, where 

 he maintained his footing by the aid of a tree which was not carried away. 



" ' M. Escher estimated at eight hundred millions of cubic feet the mass of 

 water which had accumulated at the time it began to flow out by the 

 tunnel. This mass had been reduced to five hundred and thirty millions 

 in the course of the three days following, and the level of the lake was 

 lowered by 45 feet. If the txmnel had not been made the lake would have 

 risen 50 feet higher, and the mass of water would have attained a measure- 

 ment of seventeen hundred and fifty millions of cubic feet when it began to 

 flow over the dyke, instead of the five hundred and thirty millions to which 

 it had been reduced when it began to pass across the tunnel, and would 

 have spread its ravages over the whole of the lower Valais.' " 



M. Culmann goes on to say, — " When, in the course of the winter of 

 1821-22, the dyke of ice threatened to form again, and had already covered 

 about 400 metres, or upwards of 1300 feet, of the bed of the Drause, 

 M. Venetz undertook to destroy this mass of ice, the face of which 

 measured 22,300 square metres. 



" He succeeded completely in doing this by the help of wooden aqueducts, 

 leading on to the glacier streamlets of water from the mountain Alia, heated 

 in some measure by passing over the rock ; by these means were made great 

 gashes, which detached blocks of 800 and 1000 cubic feet in measurement. 

 In falling down, these broke in pieces, which were carried away by the Drause. 



"After having destroyed the cone of the glacier, from 1822 to 1824, M. 

 Venetz undertook precautionary works to prevent the blocks of ice precipi- 

 tating themselves anew to the depth of the valley. He constructed simple 

 barriers across the valley over against the glacier. The summits of these 

 are perfectly straight and horizontal ; they produce thus so great a lateral 

 extension of the surface of the water, that the ice-work cannot make a vault 

 across it. The blocks of ice fall, then, always into the waters, remain con- 

 stantly in contact with this, and melt away by degrees. Thus the stream 

 can never be covered up, and the blocks of ice cannot precipitate themselves 

 further. From the time that the cone overhangs, by 2 or 3 mfetres, 7 or 10 

 feet, the stream which has dug away its base, the portion in front detaches 

 itself, and is borne away. These sometimes fall beyond the stream, and 

 form a small glacier at the side of the moraine, on the left bank. And these 

 masses maintain their ground sometimes for a pretty long time, but they 

 can never cover up completely the stream. 



" From that time onward — that is to say, from 1826^ — these larrages 

 have sufficed to prevent the ice-work from covering up the Drause, and thus 

 damming up the valley. 



" In acknowledging the great merit of these works, we may express the 

 wish that the engineers of this canton could be enabled always to avail them- 

 selves of the means necessary to maintain such useful structures, so as to 



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