not to drop it on his
companion's head.

The structural composition of ice is a study in itself. To the cursory
glance a piece of glacier-ice appears homogeneous, but when dissected
in detail it is found to be formed of many crystalline, interlocking
grains, ranging in size from a fraction of an inch to several inches
in diameter. A grain-size of a half to one inch is perhaps commonest in
Antarctic glacier-ice.

The history of Antarctic glacier-ice commences with the showers of snow
that fall upon the plateau. The snow particles may be blown for
hundreds of miles before they finally come to rest and consolidate.
The consolidated snow is called neve, the grains of which are
one-twenty-fifth to one hundredth of an inch in diameter, and, en masse,
present a dazzling white appearance on account of the air spaces which
occupy one-third to one-half of the whole. In time, under the influence
of a heavy load of accumulated layers of neve, the grains run
together and the air spaces are eliminated. The final result is clear,
transparent ice, of a more or less sapphire-blue colour when seen in
large blocks. It contains only occasional air-bubbles, and the size of
the grains is much increased.

Lake-ice, freezing from the surface downwards, is built up of long
parallel prisms, like the cells of a honey-comb on a large scale. In a
lakelet near the Hut this was beautifully demonstrated. In some places
cracks and fissures filled with snow-dust traversed the body of the
ice, and in other places long strings of beaded air-bubbles had become
entangled in the process of freezing. To lie down on the clear surface
and gaze "through the looking-glass" to the rocky bottom, twenty feet
below, was a glimpse into "Wonderland."

In the case of sea-ice, the simple prismatic structure is complicated
owing to the presence of saline matter dissolved in the sea water.
The saline tracts between the prisms produce a milky or opalescent
appearance. The prisms are of fresh water ice, for in freezing the brine
is rejected and forced to occupy the interstices of the prisms. Water of
good drinking quality can be obtained by allowing sea water ice to thaw
partially. The brine, of lower freezing-point, flows away, leaving only
fresh water ice behind. In this way blocks of sea-ice exposed to the
sun's rays are relieved of their salty constituents, and crumble into
pellucid gravel when disturbed.

A popular subject commanding general interest, apart from t