of the rock. The extreme edges, too, of the ice, presented a very
peculiar appearance. The general thickness, as has been said, varied
from a foot to a foot and a half; and this diminished gradually along
horizontal lines, till, at the edges of the sheet, where the ice ceased,
it became of course nothing. The extreme edge was formed of globular or
hemispherical beads of ice, like the freezing of a sweating-stone, lying
so loosely on the rock that I could sweep them off in detail with one
hand, and catch them with the other as they fell. Passing farther on
towards the thicker parts of the ice, these beads stood up higher and
higher, losing their roundness, and becoming compressed into prisms of
all shapes, in very irregular imitation of the cellular tissue in
plants, the axes of the prisms following the generally-observed law.
There seems to be nothing in this phenomenon which cannot be accounted
for by the supposition of gradual thaw of small amount being applied to
a sheet of prismatic ice.

One fact was remarkable from its universal appearance. Wherever an
incision was made in this sheet of ice, the prisms snapped off at the
depth of an inch, and could be mowed down like corn by means of a stout
knife. Although they broke naturally at this constant depth, and left a
surface of limpid ice without any signs of external or internal
division, still the laminae obtained by chiselling this lower surface
carefully, broke up regularly into the shapes to be expected in sections
of prisms cut at right angles to the axis. The roughness of my
instruments made it impossible to discover how far this extended, and
whether it ceased to be the case at any given depth in the ice.

The sea of ice on the floor was in a very wet state at the surface,
being at a lower level than the stones on to which the rain from the
open hole fell; and here the prismatic structure was not apparent to the