Gideon Spilett did not cease from pondering over this new and inexplicable incident, the appearance of a fire on the coast of the island. The fire had actually been seen! His companions, Herbert and Pencroft, had seen it with him! The fire had served to signalize the position of the island during that dark night, and they had not doubted that it was lighted by the engineer's hand; and here was Cyrus Harding expressly declaring that he had never done anything of the sort! Spilett resolved to recur to this incident as soon as the "Bonadventure" returned, and to urge Cyrus Harding to acquaint their companions with these strange facts. Perhaps it would be decided to make in common a complete investigation of every part of Lincoln Island.

However that might be, on this evening no fire was lighted on these yet unknown shores, which formed the entrance to the gulf, and the little vessel stood off during the night.

When the first streaks of dawn appeared in the western horizon, the wind, which had slightly fallen, shifted two points, and enabled Pencroft to enter the narrow gulf with greater ease. Towards seven o'clock in the morning, the "Bonadventure," weathering the North Mandible Cape, entered the strait and glided on to the waters, so strangely enclosed in the frame of lava.

"Well," said Pencroft, "this bay would make admirable roads, in which a whole fleet could lie at their ease!"

"What is especially curious," observed Harding, "is that the gulf has been formed by two rivers of lava, thrown out by the volcano, and accumulated by successive eruptions. The result is that the gulf is completely sheltered on all sides, and I believe that even in the stormiest weather, the sea here must be as calm as a lake."

"No doubt," returned the sailor, "since the wind has only that narrow entrance between the two capes to get in by, and, besides, the north cape protects that of the south in a way which would make the entrance of gusts very difficult. I declare our 'Bonadventure' could stay here from one end of the year to the other, without even dragging at her anchor!"

"It is rather large for her!" observed the reporter.

"Well! Mr. Spilett," replied the sailor, "I agree that it is too large for the 'Bonadventure,' but if the fleets of the Union were in want of a harbor in the Pacific, I don't think they would ever find a better place than this!"

"We are in the shark's mouth," remarked Nab, alluding to the form of the gulf.

"Right into its mouth, my honest Nab!" replied Herbert, "but you are not afraid that it will shut upon us, are you?"

"No, Mr. Herbert," answered Neb, "and yet this gulf here doesn't please me much! It has a wicked look!"

"Hallo!" cried Pencroft, "here is Neb turning up his nose at my gulf, just as I was thinking of presenting it to America!"

"But, at any rate, is the water deep enough?" asked the engineer, "for a depth sufficient for the keel of the 'Bonadventure' would not be enough for those of our iron-clads."

"That is easily found out," replied Pencroft.

And the sailor sounded with a long cord, which served him as a lead-line, and to which was fastened a lump of iron. This cord measured nearly fifty fathoms, and its entire length was unrolled without finding any bottom.

"There," exclaimed Pencroft, "our iron-clads can come here after all! They would not run aground!"

"Indeed," said Gideon Spilett, "this gulf is a regular abyss, but, taking into consideration the volcanic origin of the island, it is not astonishing that the sea should offer similar depressions."

"One would say too," observed Herbert, "that these cliffs were perfectly perpendicular; and I believe that at their foot, even with a line five or six times longer, Pencroft would not find bottom."

"That is all very well," then said the reporter, "but I must point out to Pencroft that his harbor is wanting in one very important respect!"

"And what is that, Mr. Spilett?"

"An opening, a cutting of some sort, to give access to the interior of the island. I do not see a spot on which we could land." And, in fact, the steep lava cliffs did not afford a single place suitable for landing.