ther mountains; what they have hurled forth has
built them up. For instance, Etna has poured forth a volume of lava
larger than itself; and the Monte Nuovo, near Naples, was formed by
ashes in the short space of forty-eight hours. The heap of rocks
composing Queen's Island had evidently come from the bowels of the
earth. Formerly the sea covered it all; it had been formed long since
by the condensation of the vapor on the cooling globe; but in
proportion as the volcanoes of the Old and New World disappeared, they
were replaced by new craters.

In fact, the earth can be compared to a vast spheroidal boiler. Under
the influence of the central fire an immense quantity of vapor is
generated, which is exposed to a pressure of thousands of atmospheres,
and which would blow up the globe, were it not for the safety-valves
opening on the outside.

These safety-valves are the volcanoes; when one closes, another opens;
and at the poles, where, doubtless in consequence of the flattening of
the earth's surface, the crust is thinner, it is not strange that a
volcano should be suddenly formed by the upheaval of the bottom of the
waves. The doctor noticed all this as he followed Hatteras; his foot
sank into a volcanic tufa, and the deposits of ashes, volcanic stones,
etc., like the syenite and granite of Iceland. But he attributed a
comparatively recent origin to the island, on account of the fact that
no sedimentary soil had yet formed upon it. Water, too, was lacking.
If Queen's Island had existed for several years, there would have been
springs upon it, as there are in the neighborhood of volcanoes. Now,
not only was there no drop of water there, but the vapors which arose
from the stream of lava seemed absolutely anhydrous.

This island, then, was of recent formation; and since it appeared in
one day, it might disappear in another and sink beneath the ocean.

The ascent grew more difficult the higher they went; the sides of the
mountain became nearly perpendicular, and they had to be very careful
to avoid accident. Often columns of cinders were blown about them and
threatened to choke them, or torrents of lava barred their path. On
some such places these streams were hard on top, but the molten stream
flowed beneath. Each one had to test it first to escape sinking into
the glowing mass. From time to time the crater vomited forth huge
red-hot rocks amid burning gases; some of these bodies burst in the
air like shells, and the fr