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thoughtful reader.
The solution of this apparent difficulty is afforded
by the fact that there is no such thing within the
range of human knowledge as absolute solid, or
perfectly rigid matter. The “solid foundations of
the earth,” as we call them—the rocks of the
earth’s crust—have a certain amount of viscosity
or limited fluidity, well shown by earthquakes,
when the earth heaves in billows like the sea, and
these great waves radiate in all directions from
the centre of disturbance. The bending down of
the rocks above a coal mine illustrates the same
property. Ice has a high degree of such viscosity.
Fragments of ice, whether large or small, may be
moulded to any desired shape by pressure, and the
cast thus obtained is clear transparent ice, the
united particles cohering into a single piece.
Substances generally that are semi-fluid may be
similarly welded together; thus malleable iron,
which passes through an intermediate condition
before melting, is welded or joined by simply
placing two clean heated surfaces together and
hammering. Platinum and glass, which soften in
like manner before fusion, are weldable; so are
many other substances, such as lead, wax, &c.
Ice is one of these. Although its melting point
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