He could fancy a half-dozen pairs of maliciously glittering eyes fastened even now upon the crest and edges of the terrace, all hidden by the thickets. Had the poisoned dart from a blowpipe come winging swiftly up from the shadows of the foliage, he should not have been surprised. But not a leaf below him was disturbed. Not a sound arose to warn his eager ears. With a sense of bitter rage and humiliation in all his system, he finally crept once more to the trail, and beyond it to the cliff's final shelving. From this extremity of the heights new aspects of the island were in view, as well as different expanses of the sea. His keen eyes searched the jungle and the clearings first, with no more results than before. It was not until he gazed afar, on the darkening silver of the waters, that his search was at all rewarded. Even then, for a moment he was not wholly convinced that what he saw was not a spearlike leaf of foliage projected beyond the clean-cut edge of the farthest of the island's tufa towers. But the angle of color detached itself and receded in far perspective. It was plainly the sail of the visiting craft, previously hidden from his sight by the hill at the island's end. It was already far on a northern course, where he should not have thought to find it. The freshening breeze was heeling it over gracefully; it would vanish in less than half an hour. He wondered instantly--had they towed away his boat? Or might they have left it moored in some inlet of the island, to be taken upon some future visit? Stifling an impulse to hasten down the trail, and aware that one, or even more, of the natives might have been left concealed upon the place, to ambush himself and Elaine, or anyone else suspected of being present on the rock, he remained behind his barrier of stones, no less cautious than before. The fact that the entire morning passed in apparent security, with never the flicker of a leaf below to advertise a lurking menace, could not suffice to render Grenville careless or overconfident. He had told Elaine of their loss--which worried her less than himself. Together they maintained an all-day vigilance, half expectant of the sailing-craft's return and keyed to the highest tension of expectancy at every stirring of a shrub below them in the jungle. Grenville finally armed himself with his bow and straightest arrow, to descend the trail, go quietly over to the spring, and then to the spot from which his boat had vanished. About the pool of crystal water there was not so much as a track of human boots or feet, other than his own. There were none to be seen about the foot of the trail, where there was ample dust in which they might have been recorded.