CLOUDS AND RIVERS, ICE AND GLACIERS. 6t 



first. Here lie gives us a signal. We direct cur tele- 

 scope upon him, and then gradually raising its end in a 

 vertical plane we find, and note by sketching, a standard 

 point at the other side of the glacier. This point known, 

 and our plummet mark known, we can on any future 

 day find our line. (To render the measurements more 

 intelligible, I append on the next page an outline dia- 

 gram of the Mer de Glace, and of its tributaries.) 



164. Along the line just described ten stakes were set 

 on July 17, 1857. Their displacements were measured 

 on the following day. Two of them had fallen, but 

 here are the distances passed over by the eight re- 

 maining ones in twenty-four hours. 



DAILY MOTION OE THE MER DE GLACE. 



First Line: A A' upon the Sketch. 





East 











West 



Stake . 



. . 1 2 



3 



4 



5 



7 



9 1G 



Inches . 



. . 12 17 



23 



26 



25 



26 



27 33 



165. You have already assured yourself by a fcuai 

 contact that the body of the glacier is real ice, and you 

 may have read that glaciers move ; but the actual 

 observation of the motion of a body apparently so rigid 

 is strangely interesting. And not only does the ice 

 move bodily, but one part of it moves past another ; 

 the rate of motion augmenting gradually from 12 

 inches a day at the side to 33 inches a day at a 

 distance from the side. This quicker movement of the 

 central ice of glaciers had been already observed by 



