However, the chief business of the colonists was to make that complete exploration of the island which had been decided upon, and which would have two objects: to discover the mysterious being whose existence was now indisputable, and at the same time to find out what had become of the pirates, what retreat they had chosen, what sort of life they were leading, and what was to be feared from them. Cyrus Harding wished to set out without delay; but as the expedition would be of some days duration, it appeared best to load the cart with different materials and tools in order to facilitate the organization of the encampments. One of the onagers, however, having hurt its leg, could not be harnessed at present, and a few days' rest was necessary. The departure was, therefore, put off for a week, until the 20th of November. The month of November in this latitude corresponds to the month of May in the northern zones. It was, therefore, the fine season. The sun was entering the tropic of Capricorn, and gave the longest days in the year. The time was, therefore, very favorable for the projected expedition, which, if it did not accomplish its principal object, would at any rate be fruitful in discoveries, especially of natural productions, since Harding proposed to explore those dense forests of the Far West, which stretched to the extremity of the Serpentine Peninsula.

During the nine days which preceded their departure, it was agreed that the work on Prospect Heights should be finished off.

Moreover, it was necessary for Ayrton to return to the corral, where the domesticated animals required his care. It was decided that he should spend two days there, and return to Granite House after having liberally supplied the stables.

As he was about to start, Harding asked him if he would not like one of them to accompany him, observing that the island was less safe than formerly. Ayrton replied that this was unnecessary, as he was enough for the work, and that besides he apprehended no danger. If anything occurred at the corral, or in the neighborhood, he could instantly warn the colonists by sending a telegram to Granite House.

Ayrton departed at dawn on the 9th, taking the cart drawn by one onager, and two hours after, the electric wire announced that he had found all in order at the corral.

During these two days Harding busied himself in executing a project which would completely guard Granite House against any surprise. It was necessary to completely conceal the opening of the old outlet, which was already walled up and partly hidden under grass and plants, at the southern angle of Lake Grant. Nothing was easier, since if the level of the lake was raised two or three feet, the opening would be quite beneath it. Now, to raise this level they had only to establish a dam at the two openings made by the lake, and by which were fed Creek Glycerine and Falls River.

The colonists worked with a will, and the two dams which besides did not exceed eight feet in width by three in height, were rapidly erected by means of well-cemented blocks of stone.

This work finished, it would have been impossible to guess that at that part of the lake, there existed a subterranean passage through which the overflow of the lake formerly escaped.

Of course the little stream which fed the reservoir of Granite House and worked the lift, had been carefully preserved, and the water could not fail. The lift once raised, this sure and comfortable retreat would be safe from any surprise.

This work had been so quickly done, that Pencroft, Gideon Spilett, and Herbert found time to make an expedition to Port Balloon, The sailor was very anxious to know if the little creek in which the "Bonadventure" was moored, had been visited by the convicts.

"These gentlemen," he observed, "landed on the south coast, and if they followed the shore, it is to be feared that they may have discovered the little harbor, and in that case, I wouldn't give half-a-dollar for our 'Bonadventure.'"

Pencroft's apprehensions were not without foundation, and a visit to Port Balloon appeared to be very desirable. The sailor and his companions set off on the 10th of November, after dinner, well armed. Pencroft, ostentatiously slipping two bullets into each barrel of his rifle, shook his head in a way which betokened nothing good to any one who approached too near him, whether "man or beast," as he said. Gideon Spilett and Herbert also took their guns, and about three o'clock all three left Granite House.

Neb accompanied them to the turn of the Mercy, and after they had crossed, he raised the bridge. It was agreed that a gunshot should announce the colonists' return, and that at the signal Neb should return and reestablish the communication between the two banks of the river.

The little band advanced directly along the road which led to the southern coast of the island. This was only a distance of three miles and a half, but Gideon Spilett and his companions took two hours to traverse it. They examined all the border of the road, the thick forest, as well as Tabor Marsh. They found no trace of the fugitives who, no doubt, not having yet discovered the number of the colonists, or the means of defense which they had at their disposal, had gained the less accessible parts of the island.

Arrived at Port Balloon, Pencroft saw with extreme satisfaction that the "Bonadventure" was tranquilly floating in the narrow creek. However, Port Balloon was so well hidden among high rocks, that it could scarcely be discovered either from the land or the sea.

"Come," said Pencroft, "the blackguards have not been there yet. Long grass suits reptiles best, and evidently we shall find them in the Far West."

"And it's very lucky, for if they had found the 'Bonadventure'," added Herbert, "they would have gone off in her, and we should have been prevented from returning to Tabor Island."

"Indeed," remarked the reporter, "it will be important to take a document there which will make known the situation of Lincoln Island, and Ayrton's new residence, in case the Scotch yacht returns to fetch him."

"Well, the 'Bonadventure' is always there, Mr. Spilett," answered the sailor. "She and her crew are ready to start at a moment's notice!"

"I think, Pencroft, that that is a thing to be done after our exploration of the island is finished. It is possible after all that the stranger, if we manage to find him, may know as much about Tabor Island as about Lincoln Island. Do not forget that he is certainly the author of the document, and he may, perhaps, know how far we may count on the return of the yacht!"

"But!" exclaimed Pencroft, "who in the world can he be? The fellow knows us and we know nothing about him! If he is a simple castaway, why should he conceal himself! We are honest men, I suppose, and the society of honest men isn't unpleasant to any one. Did he come here voluntarily? Can he leave the island if he likes? Is he here still? Will he remain any longer?"

Chatting thus, Pencroft, Gideon Spilett, and Herbert got on board and looked about the deck of the "Bonadventure." All at once, the sailor having examined the bitts to which the cable of the anchor was secured,--

"Hallo," he cried, "this is queer!"

"What is the matter, Pencroft?" asked the reporter.

"The matter is, that it was not I who made this knot!"

And Pencroft showed a rope which fastened the cable to the bitt itself.

"What, it was not you?" asked Gideon Spilett.

"No! I can swear to it. This is a reef knot, and I always make a running bowline."

"You must be mistaken, Pencroft."

"I am not mistaken!" declared the sailor. "My hand does it so naturally, and one's hand is never mistaken!"

"Then can the convicts have been on board?" asked Herbert.

"I know nothing about that," answered Pencroft, "but what is certain, is that some one has weighed the 'Bonadventure's' anchor and dropped it again! And look here, here is another proof! The cable of the anchor has been run out, and its service is no longer at the hawse-hole. I repeat that some one has been using our vessel!"

"But if the convicts had used her, they would have pillaged her, or rather gone off with her."

"Gone off! where to--to Tabor Island?" replied Pencroft. "Do you think, they would risk themselves in a boat of such small tonnage?"

"We must, besides, be sure that they know of the islet," rejoined the reporter.

"However that may be," said the sailor, "as sure as my name is Bonadventure Pencroft, of the Vineyard, our 'Bonadventure' has sailed without us!"

The sailor was positive that neither Gideon Spilett nor Herbert could dispute his statement. It was evident that the vessel had been moved, more or less, since Pencroft had brought her to Port Balloon. As to the sailor, he had not the slightest doubt that the anchor had been raised and then dropped again. Now, what was the use of these two maneuvers, unless the vessel had been employed in some expedition?

"But how was it we did not see the 'Bonadventure' pass in the sight of the island?" observed the reporter, who was anxious to bring forward every possible objection.

"Why, Mr. Spilett," replied the sailor, "............