There were several things in the message or statement, however, that confirmed his earlier uneasiness. The principal of these was the statement that it was important for the possible seekers of some cavern under the greater wall of rock to visit the island only during the time when the hideously haunting sounds were at their height. This argued, he thought, that the sounds would finally subside, or altogether cease, when complications--doubtless in the form of visitors--might be expected to develop. That the visitors would be natives and, probably, Dyaks, Grenville could have no doubt. As to what there was in the cave beneath the rock, he had small curiosity only, since it was hardly likely such tools as he desired would be so concealed from a prying world, and tools alone had value for him now. He could not doubt, however, that something there was in the cave here described, for which men had risked their lives. He thought of the headless skeletons, and then of the mummy in chains. Suddenly, at thought of that guardian of the barque, his heart gave an added leap. He snatched from his pocket the parchment referred to as a map. He could instantly see, by the light of day, that the leathery substance was leather, indeed, of the most grewsomely repellent description! It was simply _tanned human skin_! And abruptly he understood that phrase--"Map on Buli shows same." The pyramids represented the island's three great hills, and other signs the cave. The pole with a knob, on the tallest hill, was the tree so near his camp. Aye, the thing was a map in very truth--and once it had been ON Buli! For Buli was he who sat in the barque, chained fast to prevent his escape! _This map he had borne, tattooed on his breast, from which it had finally been stripped!_ CHAPTER XVII FEVERISH EMPLOYMENTS HALTED A species of horror attacked the man on whom the truth had flashed. What abominable cruelties and crimes lay back of the business thus finally to some extent revealed, he could only faintly imagine. He felt quite certain of one or two things, that were not to be told to Elaine. First, he could not for a moment doubt that the barque had been brought to the island with the sole intent and purpose of looting the cave of treasure. He was equally convinced its crew had been foully slaughtered--and their heads removed. This smacked of Dyak atrocities. Finally, there was ample evidence that men of some sort had visited the island long since the wreck was stranded, and probably within the year. He had not required the warning made "important" on the sheet to urge him to haste in preparing a boat with which to attempt an escape. To learn that the haunting sounds of the tide would at length subside was a new and disquieting addition to what he had previously deduced. He had accurately hit upon the natives' superstitious awe of the sounds to account for the island's desertion.