To recount all that the boys did, even in the briefest space, would be impossible in this book, and it is not necessary, in order to relate the happenings from this time on; but some things are necessary, because we shall have to deal with incidents which took place during their adventures, and this volume also brings into the scene several characters, in addition to the three which have been named, as the principal participants.
The incidents referred to were called by the boys "the mysteries." When they landed on the island they erected a flag pole, and improvised a flag which was kept at half mast, and mounted on a high point, so that it would attract passing ships, if their island chanced to be in the path of vessels. During one of their excursions the flag pole and staff disappeared.
For the purpose of making one of the trips by water a boat was built, and they sailed it up a large stream, only to find that within ten miles of their home was an immense cataract, or falls, around which they could not porter the vessel. It was left below the falls in a secure position, and ten days later, when they went for it, were surprised at its disappearance.
Later on it was found miles away, but the little closets which they had built in to hold their food and clothing, had disappeared, and they were still more startled to find a pair of oars, which they could not have made, attached to the boat.
In repairing the boat a note was discovered, written by some one who could not have been a member of their ill-fated vessel. This added to their perplexities, for it indicated that white people had been on the island, as well as savages.
Then they found strange ropes, evidently fashioned by a crude hand; a skull of a well-developed man was picked up on the shore not far from their home; part of the wreckage of a vessel was discovered; a herd of yaks was captured and a mysterious brand deciphered on one of them.
But in their wanderings they found the entrance to a cavern, and this was explored, resulting in finding that it was formerly a pirates' lair, and they were astounded at finding immense wealth in its hidden recesses.
They industriously searched the island, and found numerous ores which were dug out and smelted and from which they were able to build many things that added to their comfort; and finally, firearms were constructed, and powder made.
They spent much of the time in chemical experiments, in hunting for and gathering the different vegetables, and fibres, and from the latter learned how to weave cloth, to make felt, and to turn skins into leather from the animals which they hunted.