CLOUDS AZV RIVERS, ICE AM) GLACIERS. 



Ill 



grasped firmly at the point o by the finger and thumb, 

 and drawn to o', keeping the distance between o' and 



Mont anveTt 



the side c r> constant. Here the length, n o of the string 

 would have stretched to n of, and the length m o to m (/, 

 and you see plainly that the stretching of the short line, 

 in comparison with its length, is greater than that of 

 the long line in comparison with its length. In other 

 words, the strain upon n o' is greater than that upon 

 mo'; so that if one of them were to break under the 

 strain, it would be the short one. 



280. These two lines represent the conditions of strain 

 upon the two sides of the glacier. The sides are held 

 back, and the centre tries to move on, a strain being 

 thus set up between the centre and sides. But the 

 displacement of the point of maximum motion through 

 the curvature of the valley makes the strain upon the 

 eastern ice greater than that upon the western. The 

 eastern side of the glacier is therefore more crevassed 

 than the western. 



281. Here indeed resides the difficulty of getting 

 along 1 the eastern side of the Mer de Glace : a difficulty 



