But the swirl was on, and the catamaran seemed possessed to bump against the ledge. In a final desperate outburst of strength, he sent the thing shooting outward. Its bow would have turned in the whirlpool then, but he drove it clear of the point. Like a madman he pulled at the clumsy oars, to reach the protection where the wall all but folded the basin from the sea. His raft was around it--half of the raft--and another good foot would have covered himself, when the blast abruptly boomed. Even out of the tail of his eye he saw the dull-red flare behind a blot that represented ragged rock in motion. A fragment no larger than a man's two fists came as straight as a cannon projectile and struck the pitted wall beside his head. He had ducked instinctively forward, which doubtless saved his life. But dozens of smaller and barely less violent fragments were broken away from the edge of the wall by the piece with the meteoric speed. One of these struck him above the ear--and down he went, face forward, on the platform, to hang with arms and shoulders loosely supported on the bridge that was used for the sockets of his rowlocks. A rain of loose pieces hissed about in the sea. The cave belched smoke like a suddenly active volcano. The tide took the raft, with its motionless burden, and floated it back whence the man had come, but not so close in the shore. Then up on the cliff, when the shock and hail had subsided from all the air about her, Elaine came inquiringly over to the brink, to receive some word that all was well. The smoke still rose from down below and obscured the face of the waters. There was nothing Elaine could discover. She waited a time that seemed very long, in her usual determination not to seem unduly alarmed or importunate concerning Sidney's safety. But at last she called his name. There was no response. Her uneasiness increased. She called again, and moved along the brink, staring eagerly down at the sea. Then at last a sound like a stifled moan escaped her whitened lips. She had seen that prostrate, helpless figure drifting down by the shore on his raft. CHAPTER XXVIII WHAT THE BLAST DISCOVERED Grenville revived, with his characteristic pertinacity. An impulse to save himself was still alive in his brain. Actuated by its survival, he struggled galvanically to rise. "Oh, please!" said a voice, that sounded remarkably familiar. "Please try to keep quiet for a little!" Yet he had to sit up, with one hand to support him, if nothing more. He was still on the raft, and there was Elaine, on her knees, pulling hard at his oars to drive the float ashore. She was dripping wet from head to foot. For a moment Grenville regarded her blankly, while the situation cleared in his brain. "What ho, skipper!" he said, a bit faintly. "You didn't swim out to this contraption?"