Then he returned, listening to the subterranean rumblings, which sounded like continuous thunder, and by nine o’clock he was at the corral.
Ayrton was waiting for him.
“The animals are attended to, sir,” said he.
“All right, Ayrton.”
“They seem to be restless, Mr. Smith.”
“Yes, it is their instinct, which does not mislead them.”
“When you are ready—”
“Take a lantern and tinder, Ayrton, and let us go.”
Ayrton did as he was told. The onagers had been unharnessed and placed in the corral, and Smith, leading, took the route to the coast.
They walked over a soil covered with the pulverulent matter which had fallen from the clouds. No animal appeared. Even the birds had flown away. Sometimes a breeze passed laden with cinders, and the two colonists, caught in the cloud, were unable to see. They had to place handkerchiefs over their eyes and nostrils or they would have been blinded and suffocated.
Under these circumstances they could not march rapidly. The air was heavy, as if all the oxygen had been burned out of it, making it unfit to breathe. Every now and then they had to stop, and it was after ten o’clock when the engineer and his companion reached the summit of the enormous heap of basaltic and porphyrytic rocks which formed the northwest coast of the island.
They began to go down this abrupt descent, following the detestable road, which, during that stormy night had led them to Crypt Dakkar. By daylight this descent was less perilous, and, moreover, the covering of cinders gave a firmer foothold to the slippery rocks.
The projection was soon attained, and, as the tide was low, Smith and Ayrton found the opening to the crypt without any difficulty.
“Is the boat there?” asked the engineer.
“Yes, sir,” answered Ayrton, drawing the boat towards him.
“Let us get in, then, Ayrton,” said the engineer.
The two embarked in the boat. Ayrton lit the lantern, and, placing it in the bow of the boat, took the oars, and Smith, taking the tiller, steered into the darkness.
The Nautilus was no longer here to illuminate this sombre cavern. Perhaps the electric irradiation still shone under the waters, but no light came from the abyss where Captain Nemo reposed.
The light of the lantern was barely sufficient to permit the engineer to advance, following the right hand wall of the crypt. A sepulchral silence reigned in this portion of the vault, but soon Smith heard distinctly the mutterings which came from the interior of the earth.
“It is the volcano,” he said.
Soon, with this noise, the chemical combinations betrayed themselves by a strong odor, and sulphurous vapors choked the engineer and his companion.
“It is as Captain Nemo feared,” murmured Smith, growing pale. “We must go on to the end.”
Twenty-five minutes after having left the opening the two reached the terminal wall and stopped.
Smith, standing on the seat, moved the lantern about over this wall, which separated the crypt from the central chimney of the volcano. How thick was it? Whether a hundred feet or but ten could not be determined. But the subterranean noises were too plainly heard for it to be very thick.
The engineer, after having explored the wall along a horizontal line, fixed the lantern to the end of an oar and went over it again at a greater height.
There, through scarcely visible cracks, came a pungent smoke, which infected the air of the cavern. The wall was striped with these fractures, and some of the larger ones came to within a few feet of the water.
At first, Smith rested thoughtful. Then he murmured these words:—
“Yes! Captain Nemo was right! There is the danger, and it is terrible!”
Ayrton said nothing, but, on a sign from the engineer, he took up the oars, and, a half hour later, he and Smith came out of Crypt Dakkar.
LXI
Smith’s recital—Hastening the work—A last visit to the corral—The combat between the fire and the water—The aspect of the island—They decide to launch the ship—The night of the 8th of March.
The next morning, the 8th of January, after a day and night passed at the corral, Smith and Ayrton returned to Granite House.
Then the engineer assembled his companions, and told them that Lincoln Island was in fearful danger—a danger which no human power could prevent.
“My friends,” said he—and his voice betrayed great emotion—“Lincoln Island is doomed to destruction sooner or later; the cause is in itself and there is no means of removing it!”
The colonists looked at each other. They did not understand him.
“Explain yourself, Cyrus,” said Spilett.
“I will, or rather I will give you the explanation which Captain Nemo gave me, when I was alone with him.”
“Captain Nemo!” cried the colonists.
“Yes; it was the last service he rendered us before he died.”
“The last service!” cried Pencroff. “The last service! You think, because he is dead, that he will help us no more!”
“What did he say?” asked the reporter.
“This, my friends,” answered the engineer. “Lincoln Island is not like the other islands of the Pacific, and a particular event, made known to me by Captain Nemo, will cause, sooner or later, the destruction of its submarine framework.”
“Destruction of Lincoln Island! What an idea!” cried Pencroff, who, in spite of his respect for Smith, could not help shrugging his shoulders.
“Listen to me, Pencroff,” continued the engineer. “This is what Captain Nemo ascertained and what I verified yesterday in Crypt Dakkar. The crypt extends under the island as far as the volcano, and is only separated from the central chimney by the wall. Now this wall is seamed with fractures and cracks, through which the sulphurous gas is already escaping.”
“Well?” asked Pencroff, wrinkling his forehead.
“Well, I have ascertained that these fractures are widening under the pressure from within, that the basalt wall is gradually bursting open, and that, sooner or later, it will give a passage to the waters
