RESTORATION OF LEVEL DURING WINTER. 259 



way in which, during winter, the glacier recovers the level 

 which it had lost by ablation during summer (p. 243). When 

 snow covers the whole surface the motion of all points of the 

 length of a glacier approaches equality. The higher parts 

 move relatively faster than the lower,* tend, as it were, to 

 overtake them, and thus to squeeze the yielding mass in a 

 vertical direction. 



* [By higher is here meant the portion of the glacier towards its origin : by 

 lower, the part next its inferior extremity.] 



