GUIDE JOANNE. 87 



foot of the precipice ; the broken fragments congeal anew and form a cone- 

 shaped glacier, which pushes before it its moraine. What ensues must be 

 given in the narrative of Guide Joanne : — ' In those years in which 

 avalanches are very frequent the heat of summer does not suffice to melt a 

 quantity of ice equal to what the mountains cast down. The enormous 

 block which then forms a bridge on the Drause becomes always larger and 

 larger, and as the arch of this bridge, dug in summer by the torrent, closes 

 up in winter, it happened in 1597, and in our own times, in 1818, that 

 the early months of spring sufficed not for the Drause to open for itself a 

 passage, and a lake was formed behind the ice. 



" ' When this became known (wrote M. Simond, some months after the 

 event), alarm spread at once, not only throughout the whoJe valley but in 

 Le Valais, and on so far as Italy. Travellers feared to take the route of 

 the Simplon ; it was felt that when this dyke should come to break up 

 there would be there a sudden d6b4cle which would sweep over the country 

 to a great distance. The preceding winter had been severe ; the ice had 

 even then cast a dam across the valley, but without stopping the water, 

 which had eaten out a passage for itself ; but a second severe winter had 

 produced such a fall of ice that the obstacle had become insurmountable 

 and impervious. 



" ' The Government sent an engineer (M. Venetz) ; he found that the dyke 

 was 110 toises (nearly 700 feet) in length from the one mountain to the 

 other, 66 toises (or about 400 feet) in height, and 500 (or 3000 feet) in 

 thickness at its base. The lake was 1200 toises (or upwards of 7000 feet) 

 in length, and had already risen to half the height of the dyke, that is to 

 say, was from 30 to 40 toises (from 180 to 240 feet) in depth. The engineer 

 determined to cut a gaUery or tunnel through the thickness of the ice, 

 beginning 54 feet above the actual level of the lake, to give time to complete 

 the work before that height should be reached by the accumulating waters, 

 which were rising at the rate of from 1 to 5 feet per day, according to the 

 temperature; and he began the work on the 11th of May at both ends of 

 the tunnel. Fifty men in relays, relieving one another alternately, wrought 

 there night and day at the peril of their lives, — one and another of the 

 avalanches which were falling every moment threatening to bury them alive 

 in the tunnel ; many were wounded by lumps of ice, or had their feet 

 frozen, and the ice was so hard that it frequently broke the pick-axes used. 

 In despite of all these difficulties the work advanced rapidly. On the 27th 

 of May a great piece of the dyke broke off from the bottom with a fearful 

 crash ; it was behoved that the whole was about to break up, or to rise in 

 a mass, and the workmen fled ; but soon they courageously resumed their 

 work. Similar accidents occurred repeatedly ; some of the floating masses, 

 calculating from the distance at which they stood above water, must have 

 had a thickness of 70 feet submerged. On the 4th June the tunnel, 608 

 feet long, was cut from end to end ; but as it had an elevation of 20 feet or 

 more in the centre it was necessary to level it. The weather had been cold, 

 and the lake had not yet risen to the level of the mouth of the tunnel, so 

 they continued to lower this till the 13th, the day on which the flow 

 commenced, at ten o'clock at night. The lake still rose for some hours ; 

 but next day at five o'clock in the afternoon it had sunk 1 foot ; on the 

 morning of the 15th, 10 feet ; on the morning of the 16th, 30 feet ; at two 

 o'clock that day the length of the lake had shrunk 325 toises (nearly 2000 

 feet), for the tunnel, being continually eaten away, lowered itself as quickly 



