CLOUDS AND RIVERS, ICE AND GLACIERS. 



107 



from the side of the glacier the crevasses would be seen 

 to point upwards ; that is to say, the ends of the fissures 

 abutting against the bounding mountain would appear 

 to be dragged down. Were you less instructed than 

 you now are, I might lay a wager that the aspect of 

 these fissures would cause you to conclude that the 

 centre of the glacier is left behind by the quicker motion 

 of the sides. 



271. This indeed was the conclusion drawn by M. 

 Agassiz from this very appearance, before he had 

 measured the motion of the sides and centre of the 

 glacier of the Unteraar. Intimately versed with the 

 treatment of mechanical problems, Mr. Hopkins imme- 

 diately deduced the obliquity of the lateral crevasses 

 from the quicker flow of the centre. Standing beside 

 the glacier with pencil and note-book in hand, I 

 would at once make the matter clear to you thus. 



272. Let A c, in the annexed figure, be one side of 

 the glacier, and b d the other ; and let the direction of 



sr 



» — >■ j 



motion be that indicated by the arrow. Let s t be a 

 transverse slice of the glacier, taken straight across it, 



