242 Prof. Huxley on the Structure of Glacier Ice. 
least trace of fissures. Minute shallow pits, however, were scat- 
tered over it, and became particularly obvious when a coloured 
fluid was poured on to the surface and then wiped away again, 
inasmuch as under these circumstances every pit retained a very 
small portion of the colour. 
The mass was, as usual, traversed by a larger or smaller num- 
ber of parallel blue veins (whose lenticular form was almost 
always very apparent, particularly in the Brenva) ; and when a 
thin section was made perpendicular to the plane of the veins 
and viewed by transmitted light, it became obvious that the ice 
formed one continuous mass, without fissures or interruptions of 
continuity of any kind. It contained, however, a multitude of 
small, closed, and perfectly distinct chambers, and it was to the 
absence or rarity of these in the course of the veins that the 
latter owed their transparency and blueness. 
The form and contents of these chambers were exceedingly 
remarkable. In a blue vein, and in those parts of the interme- 
diate “ white ice” which were contiguous to a blue vein, they 
were always round or oval disks, with extremely flat and closely 
approximated sides; so that, viewed in one plane, they looked 
like circles ; but in a plane at right angles to this, like narrow 
parallelograms. In the white ice midway between the blue 
veins, on the other hand, I very generally noticed an irregularity 
of form, which was in many instances so great that the cavities 
appeared to be ramified. The walls of the chambers very 
frequently appeared to be a little roughened, or, as it were, 
frosted. 
Every chamber, without exception, which I carefully examined 
contained both water and air. The former was commonly 
present in larger quantities than the latter, which swam as a 
bubble in the water, and could very often be made to move 
about in the chamber like the bubble of a spirit-level. It 
seemed to me, though I will not pretend to lay it down as a 
rule, that the air was more abundant in proportion to the water 
in the more irregular chambers. Where the air was in large 
proportion to the water, the bubble of course became more or 
less completely supported by the walls of the containing cavity, 
and to a certain extent assumed its form; but where, as in the 
majority of cases, the air-bubble was small in proportion to the 
water, its figure was spheroidal, and totally different from that 
of the containing cavity. I mention this particularly, because, 
as I shall show below, the chambers (which for distinction’s sake 
I will term the “ water-chambers”) have been confounded with 
the air-bubbles, and the form which is characteristic of the one 
has been erroneously ascribed to the other. 
I had no means of measuring the dimensions of the water- 
