T is not late yet, Uncle," said Jules; "you ought to tell
us about those terrible mountains, those volcanoes that the
showers of ashes come from."
At the word "volcano," Emile, who was already asleep, rubbed
his eyes and became all attention. He too wanted to hear the
great story. As usual, their uncle yielded to their
"A volcano is a mountain that throws up smoke, calcined
dust, red-hot stones, and melted matter called lava. The
summit is hollowed out in a great excavation having the
shape of a funnel, sometimes several leagues in
circumference. That is what we call the crater. The bottom
of the crater communicates with a tortuous conduit or
chimney too deep to estimate. The principal volcanoes of
Europe are: Vesuvius, near Naples; Etna in Sicily; Hecla in
Iceland. Most of the time a volcano is either in repose or
throwing up a simple plume of smoke; but from time to time,
with intervals that may be very long, the mountain grumbles,
trembles, and vomits torrents of fiery substances. It is
then said to be in eruption. To give you a general idea of
the most remarkable phenomena attending volcanic eruption, I
will choose Vesuvius, the best known of the European
 "An eruption is generally announced beforehand by a column
of smoke that fills the orifice of the crater and rises
vertically, when the air is calm, to nearly a mile in
height. At this elevation it spreads out in a sort of
blanket that intercepts the sun's rays. Some days before the
eruption the column of smoke sinks down on the volcano,
covering it with a big black cloud. Then the earth begins to
tremble around Vesuvius; rumbling detonations under the
ground are heard, louder and louder each moment, soon
exceeding in intensity the most violent claps of thunder.
You would think you heard the cannonades of a numerous
artillery detonating ceaselessly in the mountain's sides.
"All at once a sheaf of fire bursts from the crater to the
height of 2000 or 3000 meters. The cloud that is floating
over the volcano is illumined by the redness of the fire;
the sky seems inflamed. Millions of sparks dart out like
lightning to the top of the blazing sheaf, describe great
arcs, leaving on their way dazzling trails, and fall in a
shower of fire on the slopes of the volcano. These sparks,
so small from a distance, are incandescent masses of stone,
sometimes several meters in dimension, and of a sufficient
momentum to crush the most solid buildings in their fall.
What hand-made machine could throw such masses of rock to
such heights? What all our efforts united could not do even
once, the volcano does over and over again, as if in play.
For whole weeks and months these red blocks are thrown up by
Vesuvius, in numbers like the sparks of a display of
 "It is both terrible and beautiful," said Jules. "Oh! how I
should like to see an eruption, but far off, of course."
"And the people who are on the mountain?" questioned Emile.
"'They are careful not to go on the mountain at that time;
they might lose their lives, suffocated by the smoke or
crushed by the shower of red-hot stones.
"Meantime, from the depths of the mountain, through the
volcanic chimney, ascends a flux of melted mineral
substance, or lava, which pours out into the crater and
forms a lake of fire as dazzling as the sun. Spectators who,
from the plain, anxiously follow the progress of the
eruption, are warned of the coming of the lava-flood by the
brilliant illumination it throws on the volumes of smoke
floating in the upper air. But the crater is full; then the
ground suddenly shakes, bursts open with a noise of thunder,
and through the crevasses as well as over the edges of the
crater the lava flows in streams. The fiery current, formed
of dazzling and paste-like matter similar to melted metal,
advances slowly; the front of the lava-stream resembles a
moving rampart on fire. One can flee before it, but
everything stationary is lost. Trees blaze a moment on
contact with the lava and sink down, reduced to charcoal;
the thickest walls are calcined and fall over; the hardest
rocks are vitrified, melted.
"The flow of lava comes to an end, sooner or later. Then
subterranean vapors, freed from the enormous pressure of the
fluid mass, escape with more violence than ever, carrying
with them whirlwinds of fine dust
 that floats in sinister
clouds and sinks down on the neighboring plain, or is even
carried by the winds to a distance of hundreds of leagues.
Finally, the terrible mountain calms down, and peace is
restored for an indefinite time."
"If there are towns near the volcanoes, cannot those streams
of fire reach them? Cannot those clouds of ashes bury them?"
"Unfortunately all that is possible and has happened. I will
tell you about it to-morrow, for it is time to go to bed