But here a similar objection presented itself. The crate was too big and heavy to be dropped from a small boat. French tried to visualise the operation. The crate could only be placed across the stern; in any other position it would capsize the boat. Then it would have to be pushed off. This could not be done by one man; he doubted whether it could be done by two. But even if it could, these two added to the weight of the crate would certainly cause disaster. He did not believe the operation possible without a large boat and at least three men, and he felt sure the secret would not have been entrusted to so many.

It seemed to him, then, that the crate could not have been thrown in where it was found. How else could it have got there?

He thought of Mr. Morgan’s suggestion of a wreck from which it might have been washed up into the Inlet, but according to the sergeant, there had been no wreck. Besides, the crate was undamaged outside, and it was impossible that it could have been torn out through the broken side of a ship or washed overboard without leaving some traces.

French lit a fresh pipe and began to pace the deserted smoking room. He was exasperated because he saw that his reasoning must be faulty. All that he had done was to prove that the crate could not have reached the place where it was found.

For some minutes he couldn’t see the snag; then it occurred to him that he had been assuming too much. He had taken it for granted that the crate had sunk immediately on falling into the water. The weights of the crate itself, the body, and the bar of steel had made him think so. But was he correct? Would the air the crate contained not give it buoyancy for a time, until at least some water had leaked in?

If so, the fact would have a considerable bearing on his problem. If the crate had been floated to the place he was halfway to a solution.

Suddenly the possible significance of the fourteen holes occurred to him. He had supposed they were nailholes, but now he began to think differently. Suppose they were placed there to admit the water, slowly, so that the crate should float for a time and then sink? Their position was suggestive: they were at diagonally opposite corners of the crate. That meant that at least one set must be under water, no matter in what position the crate was floating. It also meant that the other set provided a vent for the escape of the displaced air.

The more French thought over the idea, the more probable it seemed. The crate had been thrown into the sea, most likely from the shore and when the tide was ebbing, and it had floated out into the Inlet. By the time it had reached the position in which it was found, enough water had leaked in to sink it.

He wondered if any confirmatory evidence of the theory were available. Then an idea struck him, and walking to the police station, he asked for Sergeant Nield.

“I want you, Sergeant, to give me a bit of help,” he began. “First, I want the weights of the crate and the bar of iron. Can you get them for me?”