Prof. Huxley on the Structure of Glacier Ice. 243 
chambers, but at a guess [ should say they varied from a tenth 
to a fiftieth or a sixtieth of an inch in diameter. 
The line of contact of the water in the water-chambers with 
the ice was optically perfectly well defined, and easily distin- 
guishable. Hence I have no hesitation in saying, that if canals 
or fissures of any appreciable size filled with water had existed 
in the ice, I must, with the magnifying power employed, have 
discovered some trace of them; but, I repeat, nothing of the 
kind was discernible in perfectly fresh ice. 
If the existence of fluid water dispersed through its substance 
in closed chambers is shown by future observations to be a 
universal character of glacier ice (and I cannot imagine that a 
structure universally prevalent in the Mer de Glace, the Géant, 
the Brenva, and, as I shall show by-and-bye, from M. Agassiz’s 
figures, in the Aar glacier also, 1s a mere local peculiarity), it 
appears to me to be a fact of primary importance. For what I 
have described is the structure of the unchanged ice of the 
glacier—of ice which has been protected from solar or atmo- 
spheric influences by that which covered it; and it must be 
remembered that the ice which is within a foot of the surface 
on the Mer de Glace opposite the Montanvert, must have 
formed a part of the very depths of the tributary glaciers. In 
other words, the ice which is at this moment, say a hundred 
feet below the surface in the Glacier du Géant, will, in conse- 
quence of ablation, form the superficial ice of some part of the 
Mer de Glace years hence. Consequently, unless it can be 
shown that the substance of a glacier, as it approaches the sur- 
face, is exposed to some influences capable of developing the 
water-chambers and their contents, it is to be presumed that 
the structure found near the surface in the lower part of a 
glacier is the structure which prevails throughout the thickness 
of the higher part; and hence that the structure described is 
that of unaltered glacier ice in general. This conclusion, as I 
shall immediately show, is directly confirmed by the boring 
experiments and by the figures of M. Agassiz. 
M. Agassiz’s deductions, however, are totally at variance with 
mine; and he is so generally quoted as an authority in these 
matters, that I feel compelled, however unwillingly, to enter 
into a detailed criticism of his views, which are contained in the 
followmg extracts from his ‘ Systéme Glaciaire,’ numbered, for 
the sake of more convenient reference, in successive order. 
_ (1) “ At its origin, near the Névé, the compact (or proper 
glacier ice) contains, like the ice of the Névé, a notable quantity 
of air. But there is this difference between the two, that in 
the compact ice the air, instead of being distributed through 
the whole mass, is united in small perfectly circumscribed 
R2 
