They formed an insuperable barrier, recalling, but with more wildness, the fiords of Norway. The "Bonadventure," coasting as close as possible along the cliffs, did not discover even a projection which would allow the passengers to leave the deck.

Pencroft consoled himself by saying that with the help of a mine they could soon open out the cliff when that was necessary, and then, as there was evidently nothing to be done in the gulf, he steered his vessel towards the strait and passed out at about two o'clock in the afternoon.

"Ah!" said Nab, uttering a sigh of satisfaction.

One might really say that the honest Negro did not feel at his ease in those enormous jaws.

The distance from Mandible Cape to the mouth of the Mercy was not more than eight miles. The head of the "Bonadventure" was put towards Granite House, and a fair wind filling her sails, she ran rapidly along the coast.

To the enormous lava rocks succeeded soon those capricious sand dunes, among which the engineer had been so singularly recovered, and which seabirds frequented in thousands.

About four o'clock, Pencroft leaving the point of the islet on his left, entered the channel which separated it from the coast, and at five o'clock the anchor of the "Bonadventure" was buried in the sand at the mouth of the Mercy.

The colonists had been absent three days from their dwelling. Ayrton was waiting for them on the beach, and Jup came joyously to meet them, giving vent to deep grunts of satisfaction.

A complete exploration of the coast of the island had now been made, and no suspicious appearances had been observed. If any mysterious being resided on it, it could only be under cover of the impenetrable forest of the Serpentine Peninsula, to which the colonists had not yet directed their investigations.

Gideon Spilett discussed these things with the engineer, and it was agreed that they should direct the attention of their companions to the strange character of certain incidents which had occurred on the island, and of which the last was the most unaccountable.

However, Harding, returning to the fact of a fire having been kindled on the shore by an unknown hand, could not refrain from repeating for the twentieth time to the reporter,--

"But are you quite sure of having seen it? Was it not a partial eruption of the volcano, or perhaps some meteor?"

"No, Cyrus," answered the reporter, "it was certainly a fire lighted by the hand of man. Besides; question Pencroft and Herbert. They saw it as I saw it myself, and they will confirm my words."

In consequence, therefore, a few days after, on the 25th of April, in the evening, when the settlers were all collected on Prospect Heights, Cyrus Harding began by saying,--

"My friends, I think it my duty to call your attention to certain incidents which have occurred in the island, on the subject of which I shall be happy to have your advice. These incidents are, so to speak, supernatural--"

"Supernatural!" exclaimed the sailor, emitting a volume of smoke from his mouth. "Can it be possible that our island is supernatural?"

"No, Pencroft, but mysterious, most certainly," replied the engineer; "unless you can explain that which Spilett and I have until now failed to understand."

"Speak away, captain," answered the sailor.

"Well, have you understood," then said the engineer, "how was it that after falling into the sea, I was found a quarter of a mile into the interior of the island, and that, without my having any consciousness of my removal there?"

"Unless, being unconscious--" said Pencroft.

"That is not admissible," replied the engineer. "But to continue. Have you understood how Top was able to discover your retreat five miles from the cave in which I was lying?"

"The dog's instinct--" observed Herbert.

"Singular instinct!" returned the reporter, "since notwithstanding the storm of rain and wind which was raging during that night, Top arrived at the Chimneys, dry and without a speck of mud!"

"Let us continue," resumed the engineer.