296 EXTERNAL APPEARANCE OF GLACIERS. 
that it did not follow, because the mass of rock 
had moved, that therefore the mass of ice had 
moved with it. They believed that the boulder 
might have slid down for that distance. Neither 
did the occasional encroachment of the glaciers 
upon the valleys prove anything ; it might be 
solely the effect of an unusual accumulation of 
snow in cold seasons. Here, then, was another 
question to be tested ; and one of my first ex- 
periments was to plant stakes in the ice to ascer- 
tain whether they would change their position 
with reference to the sides of the valley or not. 
If the glacier moved, my stake must of course 
move with it ; if it was stationary,' my stakes 
would remain standing where I had placed them, 
and any advance of other objects upon the surface 
of the glacier would be proved to be due to their 
sliding, or to some motion of their own, and not 
to that of the mass of ice on which they rested. 
I found neither the one nor the other of my 
anticipated results; after a short time, all the 
stakes lay flat on the ice, and I learned nothing 
from my first series of experiments, except that 
the surface of the glacier is wasted annually for 
a deptli of at least five feet, in consequence of 
which my rods had lost their support, and fallen 
down. Similar disappointment was experienced 
by my friend Escher upon the great glacier of 
Adctseh. 
