Personal narrative of an excursion to the hospice of the Great St. Bernard / By R. Hibbert Taylor.

  • Taylor, R. Hibbert.
Date:
1846
Catalogue details

Licence: Public Domain Mark

Credit: Personal narrative of an excursion to the hospice of the Great St. Bernard / By R. Hibbert Taylor. Source: Wellcome Collection.

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    trophe may not be familiar to all, I shall give a brief outline of the most re¬ markable before proceeding further on our route. The main body of the Dranse derives its origin from the glacier of Cher- montane, and descends by the Yal de Bagne to join its twin current from the Great St. Bernard. Early in the year 1818, it was observed that the waters of the Dranse had very much diminished in their channel at Martigny, but the circumstance does not appear to have attracted much attention at first. At length, in the month of April, some individuals, more inquisitive than the rest, ascended the stream to investigate the cause of this unusual phenome¬ non. To their astonishment and alarm, the mystery was completely solved by the discovery of a lake 12 furlongs in length, formed by the waters of the Dranse accumulated behind a barrier of ice and snow, which, slipping down from the glacier of Getroz, had fallen into a narrow defile of the Yal de Bagne, between the mountains Pleurer and Mauvoisin, where it had formed a dike 600 feet high by 400 wide, and supported upon a base of 3,000 feet. Destruction was evidently impending over the slopes beneath, for should this frozen bulwark prove unable to withstand the vis a tergo, a sea in its strength would be poured upon the devoted land, bearing ruin and destruction in its track. In this great emergency an individual was happily found whose skill and enterprise were equal to the occasion. M. Venetz, the public engineer, under¬ took to tunnel through the barrier, and thus permit the gradual escape of the imprisoned waters. He commenced his arduous task on the 10th of May, on both sides at once, and at the height of 20 yards above the surface of the lake, which level, it was presumed, the waters would not exceed during the period required for the excavation. The work was urged on night and day without intermission, by alternating gangs of miners. All that skill could suggest, or intrepid daring execute, seems to have been developed during the progress of the work; while the most judicious measures were adopted for conveying warning to the country, in case any sudden disruption of the dike should occur. By the 4th of June the perforation had been carried 600 feet through the frozen mass, but unfortunately the two shafts of the tunnel did not meet in the centre, the external one being 20 feet higher than that communicating with the lake. The floor of the former was therefore sunk to a level with the latter, and on the 13th of June the rush of water commenced. The aperture of the outlet was, however, found to be insufficient to give free egress to the flood, which accordingly accumulated above the level of the tunnel; but this fault was speedily remedied by the force and vibration of the torrent, which widened the breach, and favoured its own impetuous exit. In 56 hours the level of the lake was reduced by 30 feet, and as the floor of the gallery was rapidly lowered by the action of the stream, there was every prospect of the water being drained off gradually and with safety. An unforseen occurrence, however, suddenly defeated all their well-concerted measures, and turned these pleasing anticipations into alarm and consternation. The water, in its descent from the outer aperture of the tunnel, falling with great impetuosity upon the base of the dike, gradually loosened and detached this buttress of the whole superstructure; the icy barrier was no longer able to resist the weight of water behind it; its flood gates were thrown open, and in half an hour the