On Water and Air. 
320 
[May, 
run briefly over the maximum, or what I call the greatest 
motion of the glacier. That motion is not always at the 
middle of the glacier, but near the middle, i for . th ^.S lacler * n 
this respedt resembles a river. Owing to the ot the 
sides on the banks of the river, the water is held back, so 
that the place of maximum motion of a river is near the 
centre Across the line A a' the maximum motion is about 
o, inches in 24 hours; across the line b b' it is about 
24 inches in 24 hours ; across the line c c it is about 
Fig. 31. 
o a inches in 24 hours across the line d d it is about 
23 inches in 24 hours \ across the line E e its .maximum 
motion is about 20 inches in 24 hours. Also with the tri- 
butary glaciers the maximum motion across the line H h', 
on the Glacier du Geant, is 13 inches in 24 hours. The 
maximum motion across the line K k', on the Glacier de 
Lechaud, is 10 inches in 24 hours. Thus you see the velo- 
city of the glacier changes. As I have said, the motion of 
a glacier resembles perfectly the motion of a. river, in that 
