great water basins. There is every reason to believe
that the fractures in the rocks under the land are as numerous and
deep-going as those beneath the sea. If it were a mere question of
access to a fluid interior, volcanoes should be equally distributed on
land and sea floors. Last of all, this explanation in no wise accounts
for the intermixture of water with the fluid rock. We can not well
believe that water could have formed a part of the deeper earth in the
old days of original igneous fusion. In that time the water must have
been all above the earth in the vaporous state.

Another supposition somewhat akin to that mentioned is that the water
of the seas finds its way down through crevices beneath the floors of
the ocean, and, there coming in contact with an internal molten mass,
is converted into steam, which, along with the fluid rock, escapes
from the volcanic vent. In addition to the objections urged to the
preceding view, we may say concerning this that the lava, if it came
forth under these circumstances, would emerge by the short way, that
by which the water went down, and not by the longer road, by which it
may be discharged ten thousand feet or more above the level of the
sea.

The foregoing general account of volcanic action should properly be
followed by some account of what takes place in characteristic
eruptions. This history of these matters is so ample that it would
require the space of a great encyclopaedia to contain them. We shall
therefore be able to make only certain selections which may serve to
illustrate the more important facts.

By far the best-known volcanic cone is that of Vesuvius, which has
been subjected to tolerably complete record for about twenty-four
hundred years. About 500 B.C. the Greeks, who were ever on the search
for places where they might advantageously plant colonies, settled on
the island of Ischia, which forms the western of what is now termed
the Bay of Naples. This island was well placed for tillage as well as
for commerce, but the enterprising colonists were again and again
disturbed by violent outbreaks of one or more volcanoes which lie in
the interior of this island; at one time it appears that the people
were driven away by these explosions.

In these pre-Christian days Vesuvius, then known as Monte Somma, was
not known to be a volcano, it never having shown any trace of
eruption. It appeared as a regularly shaped mountain, somewhat over
two thousand feet hi