Prof. Huxley on the Structure of Glacier Ice. 251 
superficial ice is of the same character as the deep, suggested 
the idea that the superficial layer is the result of the operation 
of atmospheric influences ; and that just as a bed of impervious 
rock becomes broken up into fragments, separated by permeable 
interstices, down to a certain depth wherever it is exposed to 
the atmosphere, so the glacier ice when left unprotected under- 
goes a similar weathering and disintegration. I submitted this 
notion to the test of experiment in the following way :—Not far 
from the upper end of the Moraine du Noire, and on one bank 
of a stream which cuts its way down the Glacier du Géant, I 
cleared away the superficial layer and cut out a block of the 
deeper ice, which was then divided into two equal portions of 
irregular cuboidal form, and about 8 inches in the side. 
The logwood infusion was poured on both of these, and was 
retained only by such portions of the superficial layer as had 
been allowed to remain. Water poured on to the blocks ran 
off them as it would run from marble or glass, sinking only 
into the remains of the superficial layer. I then placed the 
two blocks side by side, on an elevated ridge of the glacier, 
with their natural upper faces turned towards the sun, at this 
time (1:15 p.m.) shining brightly; the one block I left with- 
out protection, while the other was just covered by a stone 
of 4 or 5 inches in thickness, resting upon its upper face. At 
1-40, that is to say in less than half an hour, I removed the 
block of stone and poured the infusion over both pieces of ice. 
The covered one could be as little infiltrated as before, while the 
face of the uncovered became at once beautifully injected, the 
fluid instantly running into a network of little superficial fissures 
which had developed themselves, and out of which the infusion 
could be only partially extracted by washing. 
Both pieces of ice were well washed, and the stone was re- 
placed on the one, while the other was left uncovered as before. 
In the course of the ensuing half-hour I examined both blocks 
several times. The covered ice remained unchanged; but in 
the uncovered, the fissures extended further and further into the 
mass, which gradually assumed throughout the granular aspect 
of the superficial layer. Water poured on its surface soaked 
into it immediately, and a small quantity of the infusion spread 
out, the moment it reached the block, in the most beautifully 
ramified figure through the fissures. Particularly large and ap- 
parent fissures could thus be frequently observed traversing the 
middle of the blue veins. At length the fissures extended com- 
pletely through the mass, which thus became truly sponge-like. 
Water poured on its surface, fillmg the iterstices, gave the 
mass a clear and semitransparent aspect, though by no means 
to be compared to that of a blue vein. But as soon as the 
