2l8 SCIENCE SKETCHES. 



heels " well placed " on some projecting shelf of 

 rock. 



At times in our descent we felt the force of 

 the tourmeiit, a wind peculiar to the high moun- 

 tains, — a sort of snow-laden whirlwind, or ''wind 

 made visible." This wind goes furiously over the 

 mountain-side, tearing off loose rocks, starting 

 avalanches, and tossing about the banks of snow. 

 Whenever one of these struck us, we lay flat and 

 clung to the rocks, lest we should be literally blown 

 off the mountain. One of our company, I remem- 

 ber, wore a narrow brimmed hat drawn down tight- 

 ly over his ears ; the tourment took it and whirled 

 it high into the air. The learned professor fell flat 

 on the ground, while every hair of his head caught 

 the rotary motion and stood straight out. 



As we went farther, we noticed more and more 

 the treacherous character of the stones on the 

 mountain side. The whole outer coat of the 

 mountain is loose, scarcely a rock anywhere on 

 the Swiss side being firmly attached. Into all 

 the joints of the strata the water from the melting 

 snow finds its way, and by the freezing of this 

 water the joints are widened and the blocks of 

 hornblende are daily pushed nearer and nearer to 

 the edge. Thus nothing is firm ; nothing is stable, 

 and each year the mountain offers a new face to 

 the weather. 



Going down the mountain is more difficult than 

 going up. This is not only on account of the men- 

 tal strain of constantly looking over precipices, but 

 because of the looseness of the rocks. Stepping 

 down on a stone, one is more apt to detach it than 



