configuration, and fill the minds of men
with fear and awe. Conceive of "a sea of fire, on which we are all
floating, land and sea,"--a boiling, seething, incandescent reservoir in
the centre of our planet; and the solution of the problem will seem to
you not difficult. Such a sea would necessarily roll its liquid matter
to and fro; and the removal of ever so small a portion from one point to
another on the earth's surface would tend to disturb the equilibrium of
the floating mass; just as, when a ship is launched into the river, the
water it displaces is carried to the opposite bank with greater or less
violence, according to the amount of displacement.

It is impossible, adds Herschel, but that this increase of pressure in
some places and relief in others must be very unequal in their bearings.
So that at some point or another our planet's floating crust must be
brought into a state of strain, and if there be a weak or a soft part a
crack will at last take place. This is exactly what happened in the
earthquake which originated the Allah Bund, or God's Wall, in Cutch.

Volcanic eruptions are easily explicable on this principle,--the volcano
being simply a vent for the passage of heated and molten matter, which
the elevating pressure of the liquid below tends to eject. It is a
well-known fact that volcanoes and earthquake-centres are nearly all
situated on the borders or in the immediate neighbourhood of seas and
oceans; and the reason would seem to be, that at such positions the
accumulation of transported matter would necessarily attain its maximum,
to whatever cause it might be due. Then again, as Herschel points out,
the eruption of scorite and lava from the mouths of volcanoes, the
result of the upward movement of the fiery liquid below, compensates in
some degree for the downward transfer of material by detritus and
alluvial deposits. Hence it may be inferred that, on the whole, the
quantity of solid matter above the ocean-level probably remains nearly
always at the same amount.

* * * * *

It is with this ease and lucidity that Sir John deals with scientific
subjects of the greatest importance,--his genius resembling the
elephant's trunk, which can balance a straw or rend an oak. In private
life he displayed a simplicity of manner in harmony with the general
unassumingness of his character. In his books as in society, in society
as in his books, he was the same,--that is, free f