right. It varies in different places, but you may take it as 6080 feet ’ere.’
French made a short calculation.
‘That is about five and three-quarter 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.
Loughor proved to be a straggling village situated on the left bank of the estuary where the latter made a right-angled bend towards the north. The two bridges ran side by side, and a couple of hundred yards apart. That carrying the road was a fine wide structure of ferro-concrete, fairly new and leading directly into the village. The railway bridge was lower down stream, considerably older and supported on timber piles. Both were about three hundred yards long, and built with short spans and many piers. The tide was out, and the usual wide mud banks were exposed on either shore.
Directly French saw the spot he felt that here indeed was what he sought. On a dark night it would have been easy to drop the crate from the road bridge in absolute secrecy. Nor, as far as he could see from the map, was there any other place from which it could have been done.
He had assumed that the criminal would select an ebb tide for his attempt in order to ensure the crate being carried as far as possible out to sea. For the same reason French believed he would choose the time of its most rapid run. That time must also be in the dead of night to minimise the risk of discovery from passing road traffic. From 2 to 4 a.m. would probably best meet the conditions, as the chances were a thousand to one that the road would then be deserted.
French wondered if he could get anything from these considerations. He turned to Manners.
‘I suppose it takes a bit of time to get up a good run in an estuary like this? How soon after high water would you say the current was running at full speed under the bridge?’
‘From one to two hours, more or less.’
One to two hours previous to the period 2 to 4 a.m. meant between midnight and 3 a.m.
‘Now, Mr Manners, can you tell me whether high water fell between twelve and three on any night about five or six weeks ago?’
Manners once more produced his tide table.
‘Five or six weeks ago,’ he repeated slowly. ‘That would be between the 16th and the 23rd of August.’ He ran his stubby finger up the pages, then read out: ‘“21st, Sunday, 0.5—” that’s five minutes past midnight, you understand. “22nd, Monday, 1.23 a.m.; 23rd, Tuesday, 2.55. a.m.” ’Ow would that suit you, sir?’
‘All right, I think,’ French answered, as he noted the three dates. ‘Any of those top springs?’
‘No, sir, you don’t get ’igh water of springs at night. ’Bout six or seven o’clock it runs. Those dates wot I gave you are about dead neaps.’
‘But there is still a strong flow at neaps?’
‘Oh, bless you, yes. Not so strong as at springs o’ course, but plenty strong enough.’
All this seemed satisfactory to French, and he felt a growing conviction that the small hours of the 21st, 22nd, or 23rd of August had witnessed the launch of the crate. But this was mere theory, and theory is popularly admitted to be worth only one-sixteenth of the value of practice. Could he not arrive at something more definite?
Suddenly he thought he saw his way.
‘You say it was neap tides on those three dates in August? What rise and fall does that represent?’
‘’Bout eighteen feet.’
‘How soon shall we have that again?’
‘Not for nearly a week we shan’t. Say next Monday.’
‘I can’t wait for that. What’s the rise tomorrow?’
‘Twenty-one foot eleven.’
‘And what hour is high water?’
‘Eight o’clock in the morning.’
‘That’ll have to do. Look, here is a bus labelled “Llanelly.” Let us get aboard.’
At the police station they found not only the superintendent, but Chief Constable Lloyd.
‘Glad to see you together, gentlemen,’ French greeted them. ‘I’ve been going into the matter of tides and currents in the Inlet with Mr Manners here, and now I want your help in trying an experiment. Manners informs me that about six weeks ago, the time at which the doctors believe our man was murdered, it was high water in the dead period of the night. Tomorrow, Thursday, it will be high water at 8. a.m. The maximum run out to sea, Manners says, will begin between one and two hours later, say at 9.30 a.m. Now, gentlemen, I want to load the crate with a weight equal to that of the body and throw it into the estuary from the Loughor bridge at 9.30 tomorrow morning. Will you help me?’
While French had been speaking the three men had stared uncomprehendingly, but as he reached his peroration something like admiration showed on their faces.
‘Well, I’m blessed,’ the superintendent said slowly, while Major Lloyd gave the suggestion his instant approval.
‘Glad you agree, gentlemen,’ said French. ‘Now, if we’re to be ready, we shall want a few things arranged. First we’ll have to put stones in the crate to equal the weight of the body. Then we’ll want a carpenter to repair the top where Mr Morgan broke it. He’ll have to make it water-tight with pitch or putty or something. I don’t want it to take any water through the cracks. A lorry will also be needed to carry the crate to the bridge, and three or four men to lift it over the parapet.’
‘Very good,’ the chief constable answered. ‘Nield can arrange all that. Advise him, will you, Superintendent. But you’d better see him yourself, Inspector, and make sure he forgets nothing. Anything else?’
‘Yes, sir. We don’t want to lose the crate. We shall want a rope round it and a boat in attendance.’
‘You can fix that up, Manners, can’t you?’
‘Certainly, sir. I’ll see to it.’
‘Good. I’ll come down to watch the experiment. Shall we say 9.30 a.m. at the bridge?’
At nine o’clock next morning two vehicles left the Burry Port police station. The first was a lorry and on it stood the crate, repaired and loaded with the necessary weight of shingle, due allowance having been made for the fact that the wood was now waterlogged. Behind followed a car containing French, Nield, and three constables in plain clothes.
The weather was ideal for their purpose. The fine spell had lasted and the sun shone with a summery warmth and brilliance. Not a breath of wind dulled the shining surface of the Inlet, now calm and placid