Captain Restronguet, Devoran, and the sub hastened to the compartment in which the detector was fixed. The indicator board was absolutely blank. "We’re not having an easy time of it at all," remarked the captain. "Without the detector it is quite possible that the ’Vorwartz’ may yet outwit us. All the same, I cannot understand it." "We know her position up to ten minutes or a quarter of an hour ago, sir," said the first officer. "Quite so, Mr. Devoran; and we must work on that. It will take us three hours, running at the highest speed compatible with prudence in this brute of a river, to arrive at the spot where the ’Vorwartz’ was last reported. In three hours Karl von Harburg may have shifted a long distance off--or he may not." "And there’s Kenwyn to be taken into account." "I haven’t forgotten him. I think after all we had better keep him on board. It is too much of an undertaking for two men to have and tend him, provide for themselves, and be on their guard against the wild animals that abound, and a dozen other difficulties that a camp on shore would entail. However, pass the word for a speed of twenty-four knots. Allowing for the adverse current we ought to be at the confluence of the Zampa River well before sunset." Just above the town of Shemba the Zambezi bifurcates, the two streams reuniting twenty miles higher up. It was just possible that the "Vorwartz," bound towards the sea, might be passing down one branch while the "Aphrodite" was proceeding up the other; but this time luck was in Captain Restronguet’s favour, for above the junction the "Aphrodite" fell in with a trading steamboat, whose captain, by signs, made it clear that no vessel of any description approaching the "Vorwartz" had passed down the left-hand stream. The river here was considerably narrower and deeper than nearer its mouth. Its width was still over half a mile, while the soundings gave a level bed of six fathoms. Here, also, the tide was no longer felt; but, owing to a cessation in the rainfall, the level of the river was gradually sinking. During the course of the day several canoes passed at a respectful distance; but late in the afternoon a craft of some sort was sighted drifting down in mid-stream. As the "Aphrodite" approached it was seen that the object was a raft composed of several slender spars supported by four barrels, to which were lashed four or five short planks. Lying on the platform thus formed were two human bodies. "What do you make of it, Mr. Devoran?" asked Captain Restronguet. "A tragedy--not exactly on the high seas--but one of a very extraordinary nature. They look like Europeans." "Shall I have the boat lowered to investigate, sir?" "No, they’re dead right enough. I’ve been watching them pretty carefully through my glass for some time. If it’s a case of contagious disease we had better sheer off." "Why, they’re Chinese!" exclaimed Hythe.