“It’s like this ’ere, Mr. French,” Manners explained. “It’s all according to ’ow the tide ’appens to be running. If the tide was flowing and that there crate was dropped in at Llanelly it would go further up the Inlet than wot you show on the chart. An’ if the tide was ebbing it would go further down. But if the tide was on the turn it might go up or down and then come back to the place. You see wot I mean?” French saw it, and he sighed as he saw also that it meant that there was practically no part of the adjacent shores from which the crate might not have come. Then it occurred to him that both his question and Manners’ reply had been based on a misconception. The murderer’s object was to get rid of the crate. Would he, therefore, choose a rising or half tide which might drift it back inshore? Surely not; he would select one which would take it as far as possible out to sea. French felt that only ebb tides need be considered. He turned again to Manners. “I suppose a good ebb develops some strong currents in these channels?” “You may say so, Mr. French. An average of five knots you may reckon on. A deal faster than you could walk.” “Five knots an hour?” “No, sir. Five knots. It’s like this ’ere. A knot ain’t a distance; it’s a speed. If I say five knots I mean five sea miles an hour.” “A sea mile is longer than an ordinary one?” “That’s right. It varies in different places, but you may take it as six thousand and eighty feet ’ere.” French made a short calculation. “That is about five and three-quarters English miles per hour,” he remarked as he scaled this distance up the Inlet from the position of the crate. And then his interest quickened suddenly. A little over five miles from the point at which the crate had sunk the estuary narrowed to less than a quarter of a mile in width. At this point it was crossed by two bridges, carrying, respectively, the main road and the railway between Swansea and Llanelly. Had the crate been thrown from one of these? French saw at once that no more suitable place for the purpose could be found. Objects pushed in from the bank would tend to hug the shore and to be caught in backwaters or eddies. Moreover, even if they escaped such traps they would not travel at anything like the maximum speed of the current. But from a bridge they could be dropped into the middle of the stream where the flow was quickest. “What about the bridge up at Loughor?” he asked. “If the crate was dropped off that on an ebb tide, do you think it would get down all right?” Manners was impressed by the suggestion. Given a good ebb, about an hour should carry the crate to where it was found. French rose with sudden energy. “Let’s go and see the place. How soon can we get there?” By a stroke of luck a train was approaching as they entered the station, and twenty minutes later they reached their destination.