Jack was still wondering how far they had come and what was to be the outcome of this odd adventure, when something happened that effectually put all other thoughts out of his head. The air became filled with a roaring sound, and spray began to dash upon the floor of the raft. With a sharp thrill of alarm Jack recognized that the roaring sound was the voice of a waterfall, and that the raft was being swept toward it at lightning speed. He seized up one of the oars and attempted to head the raft for the shore. But the oar might have been a straw for all the effect it had against that rapid current. All at once it snapped, almost hurling Jack overboard. The next instant raft, boy and unconscious man were swept into a vortex of waters. Jack felt himself falling through space. Simultaneously there came a crashing blow on his head. A million constellations seemed to swim before his eyes, and then, with a blinding flash of fire, his senses left him. [Illustration: THE NEXT INSTANT RAFT, BOY AND UNCONSCIOUS MAN WERE SWEPT INTO A VORTEX OF WATERS.] CHAPTER VI. THE POOL OF DEATH. The blow that had been dealt the boy came from one of the timbers of the raft, which had been torn to pieces as it was swept over the falls. How long Jack remained insensible he did not know; but when he recovered his senses he found himself struggling in a seething pool of water at the foot of the falls. Luckily he was able to catch hold of one of the logs of the raft as it was swept by him, and clinging to this he began to strike out with his legs, hoping to make his way to the edge of the pool. Many times during that desperate struggle for existence Jack felt certain that death would intervene before he could accomplish his purpose. Once another log, that was being swept round like a straw in that boiling vortex of foaming waters, was dashed against the one to which he clung. The shock almost forced the lad to relinquish his hold. But he hung on like grim death. Blinded by foam and half choked, the boy, with bull–dog grit, stuck to his purpose, and at last was rewarded by feeling ground under his feet. A moment later, bruised, breathless and drenched to the skin, he flung himself panting on the sandy shore of the pool, too exhausted to move further. He lay there, actually feeling more dead than alive, for a long time before he felt capable of moving. But at last he found strength to drag himself further up the bank. Fumbling in his pocket, he found that his water–tight match box was in its proper place, and in the darkness he set about making preparations to build a fire. Luckily, on the brink of the pool there was any quantity of dry wood cast up by the maelstrom of waters, and the boy soon had a roaring blaze kindled. Stripping to his underclothing he hung his other garments on sticks in front of the blaze while he basked in its cheery rays.