Manners nodded but did not reply. French unrolled his map and went on: “Here is a map of the district and this is the point at which the crate was found. Let us take the places in turn. If it had been thrown in here at Burry Port, would it have got there in time?”
“It ain’t just so easy to say,” Manners declared, slowly. “It might if the tide was flowing, and then again it mightn’t. It might ’ave started ’ere or from Pembrey—that’s ’alf a mile over there to the west.”
This was not encouraging, but French tried again.
“Very well,” he said. “Now what about Llanelly?”
Llanelly, it appeared, was also a doubtful proposition.
“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.”