370 PLEASANT WA YS IN SCIENCE. 



outrush of the imprisoned water were fearful. " In the course 

 of their descent," says one account of the catastrophe, " the 

 waters encountered several narrow gorges, and at each of 

 these they rose to a great height, and then burst with new 

 violence into the next basin, sweeping along forests, houses, 

 bridges, and cultivated land." It is said by those who wit- 

 nessed the passage of the flood at various parts of its course, 

 that it resembled rather a moving mass of rock and mud 

 than a stream of water. " Enormous masses of granite were 

 torn out of the sides of the valleys, and whirled for hundreds 

 of yards along the course of the flood." M. Escher the 

 engineer tells us that a fragment thus whirled along was 

 afterwards found to have a circumference of no less than 

 sixty yards. " At first the water rushed on at a rate of more 

 than a mile in three minutes, and the whole distance (forty-five 

 miles) which separates the Valley of Bagnes from the Lake 

 of Geneva was traversed in little more than six hours. The 

 bodies of persons who had been drowned in Martigny were 

 found floating on the further side of the Lake of Geneva, near 

 Vevey. Thousands of trees were torn up by the roots, and 

 the ruins of buildings which had been overthrown by the 

 flood were carried down beyond Martigny. In fact, the 

 flood at this point was so high, that some of the houses in 

 Martigny were filled with mud up to the second story." 



It is to be noted respecting this remarkable flood, that 

 its effects were greatly reduced in consequence of the efforts 

 made by the inhabitants of the lower valleys to make an 

 outlet for the imprisoned waters. It was calculated by M. 

 Escher that the flood carried down 300,000 cubic feet of 

 water every second, an outflow five times as great as that of 

 the Rhine below Basle. But for the drawing off of the 

 temporary lake, the flood, as Lyell remarks, would have 

 approached in volume some of the largest rivers in Europe. 

 " For several months after the debacle of 1818," says Lyell, 

 ' the Dranse, having no settled channel, shifted its position 

 continually from one side to the other of the valley, carrying 

 away newly erected bridges, undermining houses, and 



