For the boat was back, the screw throbbing, and the prisoner peering through his porthole across the sunlit waters that he believed had closed for ever over his comrade's head. Suddenly the sun sank behind the Island of Elba, the lane of dancing sunlight was instantaneously quenched and swallowed in the trackless waste, and in the middle distance, already miles astern, either my sight deceived me or a black speck bobbed amid the gray. The bugle had blown for dinner: it may well be that all save myself had ceased to strain an eye. And now I lost what I had found, now it rose, now sank, and now I gave it up utterly. Yet anon it would rise again, a mere mote dancing in the dim gray distance, drifting towards a purple island, beneath a fading western sky, streaked with dead gold and cerise. And night fell before I knew whether it was a human head or not.