Phillip raised his eyebrows. “Then,” said he, “this is a very remarkable affair. I distinctly remember on that occasion, when we had sunk all the bottles, reloading the revolver with Eleys, and that there were then three cartridges left over in the bag. When I had loaded, I opened the new box of Curtis and Harveys, tipped them into the bag and threw the box overboard.”
“Did you clean the revolver?” asked Thorndyke.
“No, I didn’t. I meant to clean it later, but forgot to.”
“But,” said Thorndyke, “it has undoubtedly been cleaned, and very thoroughly as to the barrel and one chamber. Shall we check the cartridges in the bag? There ought to be forty-nine Curtis and Harveys and three Eleys if what you have told us is correct.”
Phillip searched among the raffle on the bench and presently unearthed a small linen bag. Untying the string, he shot out on the bench a heap of cartridges which he counted one by one. There were fifty-two in all, and three of them were Eleys.
“Then,” said Thorndyke, “it comes to this: since you used that revolver it has been used by some one else. That some one fired only a single shot, after which he carefully cleaned the barrel and the empty chamber and reloaded. Incidentally, he seems to have known where the cartridge bag was kept, but he did not know about the change in the make of cartridges or that the revolver had not been cleaned. You notice, Rodney,” he added, “that the circumstantial evidence accumulates.”
“I do, indeed,” Rodney replied, gloomily. “Is there anything else that you wish to examine?”
“Yes. There is the sail. Phillip mentioned a stain on the jib. Shall we see if we can make anything of that?”
“I don’t think you will make much of it,” said Phillip. “It is very faint. However, you shall see it and judge for yourself.” He picked out one of the bundles of white duck, and, while he was unfolding it, Thorndyke dragged an empty bench into the middle of the floor under the skylight. Over this the sail was spread so that the mysterious mark was in the middle of the bench. It was very inconspicuous; just a faint grey-green, wavy line like the representation of an island on a map. The three men looked at it curiously for a few moments; then Thorndyke asked: “Would you mind if I made a further stain on the sail? I should like to apply some reagents.”
“Of course you must do what is necessary,” said Rodney. “The evidence is more important than the sail.”