"“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<...>"
1. https://www.gutenberg.org/files/1268/1268-h/1268-h.htm#link2...