Smyth says: "The symptoms which precede an eruption are generally
irregular clouds of smoke, ferilli or volcanic lightnings, hollow
intonations and local earthquakes that often alarm the surrounding
country as far as Messina, and have given the whole province the name
of Val Demone, as being the abode of infernal spirits. These agitations
increase until the vast cauldron becomes surcharged with the fused
minerals, when, if the convulsion is not sufficiently powerful to force
them from the great crater (which, from its great altitude and the
weight of the candent matter, requires an uncommon effort), they explode
through that part of the side which offers the least resistance with a
grand and terrific effect, throwing red-hot stones and flakes of fire to
an incredible height, and spreading ignited cinders and ashes in every
direction."
After the eruption of ashes, lava frequently follows, sometimes rising
to the top of the cone of cinders, at others disrupting it on the least
resisting side. When the lava has reached the base of the cone it begins
to flow down the mountain, and, being then in a very fluid state, it
moves with great velocity. As it cools, the sides and surface begin to
harden, its velocity decreases, and after several days it moves only
a few yards an hour. The internal portions, however, part slowly with
their heat, and months after the eruption clouds of steam arise from the
black and externally cold lava-beds after rain; which, having penetrated
through the cracks, has found its way to the heated mass within.
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