“Where you lost time,” said Leyland, “was in clambering up those steps. I calculated that you might have saved three minutes if you’d swum out to the canoe higher up and started paddling at once. What the deuce did the man do it for, considering the waste of time? Burgess can hardly be lying about those footprints.”
“I believe I’m just beginning to understand that. Look at it this way—the sixth photograph, we now know, wasn’t taken till the evening. Hitherto we imagined that the footprints were left on the bridge when Nigel (or somebody) went up to take the photograph of Derek in the canoe. But the footsteps were there in the morning, and the photograph wasn’t taken till the evening. Then why were the footprints there at all? You saw me walking up those steps backwards, and I must have looked a fool as I did it; certainly I felt a fool. It was, as you say, sheer waste, of time. Which makes me suspect that the footprints were left there on purpose, in order to create a certain impression.”
“That’s all very well, but it was a mere fluke that Burgess went along and saw them. If he hadn’t happened to go just then, they’d have made no impression on anyone, because nobody would have seen them.”
“Precisely. And, don’t you see, that’s why it was necessary to photograph them. The marks were made in order that they might be photographed. And the photograph was left about on purpose. Now, what impression was it that the murderer was trying to make?”
“God knows.”
“So do I. The silly part about these footsteps from the first is that they only went up one set of stairs, instead of two, and that they only went one way, instead of coming and going. That suggested to us either that somebody in the canoe had pulled himself up by his arms on to the bridge and walked off it, or else that somebody had walked up the steps, backwards, and then jumped from the bridge into the stream. Either notion is pretty good nonsense, and therefore neither notion is the impression which this rather acute criminal intended to convey.”
“Pity he didn’t take more trouble to make his impressions foolproof.”
“Don’t you see why? He thought that old Burgess would go on rootling in his garden; how was it to be expected that he would suddenly start hen-hunting in the wooded part of the island? Those footprints were not meant to be seen by Mr. Burgess, or by any human eye.”
“Then why on earth—”
“They weren’t meant to be seen, but the photograph was meant to be seen. Now, suppose Burgess had never observed or reported the footprints, and yet we had discovered the photograph, what should we suppose about the footprints?”
“I see what you mean. We should suppose that they went right across the bridge, from one side to the other, and along both sets of stairs. … Yes, I see. They were meant to look like the footprints of a man walking across, barefoot, from the Western bank of the river to the island?”
“Talk sense. If the man was walking that way, and took the photograph as he did it, the film wouldn’t register any footprints, because the footprints wouldn’t have happened yet. You must make your footprints first and photograph them afterwards. No, the film was meant to look as if it represented the tracks of a man walking backwards, from the island to the Western bank. In fact, to suggest that the murderer was somebody who went off afterwards in the direction of Byworth.”
“In other words, that he did not go off by river, nor in the direction of Spinnaker Farm and the station.”
“Exactly. Which recalls to us the interesting fact that there was one person who certainly did go off in the direction of the station, and that was Nigel.”
“Hullo! You are coming down on that side, then?”
“I didn’t say so. But I’m not exactly taking my eye off Nigel just yet, that’s all.”
“Meanwhile, have you got a match?”
“Just used my last. There’s an automatic machine on the other platform, though. We’ll go across and talk to it, and then get back.”
As they stood on the down platform there was a rumble and a whistle from near by, and a desultory porter showed signs of interest. A train puffed in from the Oxford direction, with the self-importance of one who is conscious that he is a rare visitor. A single passenger got out, a tall, well-built young man in a brown aquascutum which half concealed and half revealed the fact that he wore shorts underneath it. Confronted with the desultory porter, he began an exhaustive search of his pockets, and was rewarded at last by the discovery of his ticket; but not before a pink, perforated slip had fluttered to the ground unregarded. Unregarded, I mean, by the principals in the action; Leyland and Bredon exchanged an immediate glance, and the stranger’s back was hardly turned before they pounced upon it.
“This is too good to be true,” said Leyland as they turned it over. “It’s quite, quite certainly the one the man in the punt took at Eaton. F.N.2, as I live—the beastly number would have been found written on my heart if we hadn’t come across this. Quick, what do we do?”
“I’m going back to the canoe and upstream to meet him. He can’t be coming back to pick up the punt. Look, he’s gone off along the road—towards Millington Bridge.”
“I’ll follow, I think, and if he goes downstream you can take me on board when we
