GLACIÈRE OF S. GEORGES.]

It was natural to examine the structure of the ice in this glacière,
after what we had observed on La Genollière. The same prismatic
structure was universal in the sheet on the wall, and in the blocks
which lay here and there on the floor and formed the sole remains of
former columns. It was to be observed also in many parts of the
ice-floor itself. The base of one large column still remained standing
in its original position, and its upper end presented a tolerably
accurate horizontal section of the column. The centre was composed of
turbid ice, round which limpid prisms were horizontally arranged,
diverging like the feathers of a fan; then came a ring of turbid ice,
and then a second concentric ring of limpid prisms, diverging in the
same manner as those which formed the inner ring. There were in all
three or four of these concentric rings, the details showing a
considerable amount of confusion and interference: the general law,
however, was most evident, and has held in all the similar columns which
I have since examined in other glacières. The rings were not accurately
circular, but presented rather the appearance of having been formed
round a roughly-fluted pillar on an elliptical base.

The examination of the ice on the wall gave some curious results. The
horizontal arrangement of the prisms, which we had found to prevail in
vertical columns, was here modified to suit the altered conditions of
the case, and the axes of the prisms changed their inclination so as to
be always perpendicular to the surface on which the ice lay, as far as
could be determined by the eye. Thus, in following the many changes of
inclination of the wall, the axes of the prisms stood at many different
angles with the vertical, from a horizontal position where the wall
chanced to be vertical, to a vertical position on the horizontal ledges