Prof. Huxley on the Structure of Glacier Ice. 253 
(9) “ The quantity of bubbles with which the white ice is 
filled, is the reason why the fissures are more slowly propa- 
gated in it; the air, by its elasticity, being unfavourable to 
the formation of fissures (l’air qui est de sa nature élastique ne 
favorisant aucunement le crevassement). By degrees, however, 
and in proportion as the infiltration perpetuates itself, the ri- 
gidity increases, and the fissures multiply in proportion. Every 
bubble that a fissure meets in its course loses its aériform con- 
tents. It becomes transparent, and the opacity of the mass 
is so far diminished. The consequence of this multiplication of 
fissures is continually to diminish the number of bubbles, and 
by this means to render the ice more and more transparent and 
blue. 
“Tt will be evident to any one who has followed the progress 
of modern physics, that this phenomenon is due solely to the 
diathermanicity of ice. The air first and then the water becomes 
heated through the ice. However minute may be the degree of 
heat which is thus transmitted to them, it is enough to melt a 
part of the ice which surrounds them, and thereby to increase 
the cavity in which they are imprisoned. I do not think, how- 
ever, that any very great importance should be ascribed to this 
phenomenon ; and the fact that it is produced only when the ice 
is exposed directly to the rays of the sun, is in my eyes an indi- 
cation that it exercises no notable influence on the mechanism 
of glaciers.”—P. 157. 
(10) “‘ When the ice has acquired a certain degree of trans- 
parency, and the network of capillary fissures is fully established 
in it, water and air penetrate into the fissures with great facility. 
One may assure oneself of this in many ways, among others by 
the following experiment, which I have repeated many times. 
Let a cube of ice of a few decimetres on the side be detached 
from the bottom of a crevasse, in that part of the glacier where 
the ice is most transparent, and placed upon a rock. At first, 
a few fissures will appear on the surface, then these fissures will 
be gradually propagated into the interior, and the network be- 
coming more and more complex, will by degrees reach the base. 
If, then, the block of ice be turned upside down, and water be 
poured upon it, all the fissures will disappear from above down- 
wards, in the same order as they were formed. The block will 
remain perfectly transparent so long as it is saturated; but so 
soon as one leaves off watering, the fissures reappear where they 
last appeared when the block was reversed.”—P. 161. 
11) “The angular fragments are the consequence and the 
product of the capillary fissures. When a morsel of compact 
ice is exposed for some time to the air, it becomes decomposed 
into a certain number of angular fragments,which are the smaller 
