252 Prof. Huxley on the Structure of Glacier Ice. 
supply of water ceased, the fissures of the side uppermost imme- 
diately began to lose their water, which drained away below, and 
becoming filled with air, a whitish opake hue succeeded. On 
reversing the block suddenly, what had been its under surface 
appeared at first clear, but the water soon deserting it, it rapidly 
whitened, while the previous upper and white surface became 
clear. Water poured upon the upper surface, traversed the mass 
and flowed out again below with the utmost ease. In fact it is 
impossible to conceive any more striking contrast in these re- 
spects, than that between the freshly extracted ice-block (or that 
which had remained under cover) and that which had been exposed. 
So far as it may be permissible to draw a conclusion from 
the few experiments I made, I should say that direct exposure 
to the sun has much influence on the rapidity of this process of 
weathering ; but it is by no means essential, for the northern 
faces of the walls of crevasses exhibit a well-developed super- 
ficial layer; and I have seen it even beneath huge boulders, 
where these were not in direct contact with the ice. 
But one conclusion appears to me to be deducible from these 
experiments, and that is in perfect accordance with the results 
of ocular investigation. Glacier ice is essentially devoid of all 
pores, fissures and cavities, save the closed water-chambers ; 
though of course, like all other brittle bodies, it is hable to be- 
come fissured and fractured by pressure from without. Fissures 
and cavities produced in this way, however, are accidental and 
not essential. But itis a remarkable feature of glacier ice, 
that it is liable to weather in a peculiar manner, becoming fis- 
sured and breaking up into irregular fragments to a certain 
depth. The superficial layer formed in this way is eminently 
porous, and absorbs fluids like a sponge. 
In arriving at these results, however, I again regret to find 
myself in direct opposition to the current doctrine based on the 
statements of Prof. Agassiz, from whose ‘ Systéme Glaciaire’ I 
continue my series of quotations. 
(8) “ Capillary fissures—The true capillary fissures are very 
different from the superficial fissures which have just been de- 
scribed (3). They exist not merely at the surface, but are found 
on the walls of crevasses and in the interior of cavities where 
the rays of the sun never penetrate. They are larger than the 
little fissures which have just been mentioned, and far less nu- 
merous, particularly in the regions in which the latter abound. 
Their distribution is not uniform in the interior of the compact 
ice,” p. 154; but (M. Agassiz goes on to explain) they are ar- 
ranged in bands and zones, which, becoming more completely in- — 
filtrated with water than the intermediate ice, appear blue and 
transparent, and are the blue veins. 
