ford you the explanation which, during our few minutes of private
conversation, was given me by Captain Nemo."

"Captain Nemo!" exclaimed the colonists.

"Yes, and it was the last service he desired to render us before his
death!"

"The last service!" exclaimed Pencroft, "the last service! You will see
that though he is dead he will render us others yet!"

"But what did the captain say?" inquired the reporter.

"I will tell you, my friends," said the engineer. "Lincoln Island does
not resemble the other islands of the Pacific, and a fact of which
Captain Nemo has made me cognizant must sooner or later bring about the
subversion of its foundation."

"Nonsense! Lincoln Island, it can't be!" cried Pencroft, who, in spite
of the respect he felt for Cyrus Harding, could not prevent a gesture of
incredulity.

"Listen, Pencroft," resumed the engineer, "I will tell you what Captain
Nemo communicated to me, and which I myself confirmed yesterday, during
the exploration of Dakkar Grotto.

"This cavern stretches under the island as far as the volcano, and is
only separated from its central shaft by the wall which terminates it.
Now, this wall is seamed with fissures and clefts which already allow
the sulphurous gases generated in the interior of the volcano to
escape."

"Well?" said Pencroft, his brow suddenly contracting.

"Well, then, I saw that these fissures widen under the internal pressure
from within, that the wall of basalt is gradually giving way and that
after a longer or shorter period it will afford a passage to the waters
of the lake which fill the cavern."

"Good!" replied Pencroft, with an attempt at pleasantry. "The sea will
extinguish the volcano, and there will be an end of the matter!"

"Not so!" said Cyrus Harding, "should a day arrive when the sea, rushing
through the wall of the cavern, penetrates by the central shaft into the
interior of the island to the boiling lava, Lincoln Island will that day
be blown into the air--just as would happen to the island of Sicily were
the Mediterranean to precipitate itself into Mount Etna."

The colonists made no answer to these significant words of the engineer.
They now understood the danger by which they were menaced.

It may be added that Cyrus Harding had in no way exaggerated the danger
to be apprehended. Many persons have formed an idea that it would be
possible to extinguish volcanoes, which are almost always situated on
the shores of a sea or lake