"Make aught new out of it, sir?" he asked after a while.
Instead of answering, Allerdyke laid the photograph down, went across to another table, and took from it his album. He turned its leaves over until he came to a few loose prints. He picked them up one after another and examined them. And suddenly he knew the secret. There was no longer any problem, any difficulty about that photograph. He knew—now! And with a sharp exclamation, he flung the album back to the side-table, and turned to the detective.
"Chettle!" he said. "You know me well enough to know that I can make it well worth any man's while to keep a secret until I tell him he can speak about it! What!"
"I should think so, Mr. Allerdyke," responded Chettle, readily enough.
"And if you want me to keep a secret—"
"I do—for the time being," answered Allerdyke. He sat down again and picked up the photograph which had exercised his thoughts so intensely. "I've found out the truth concerning this," he said, tapping it with his finger. "Yes, I've hit it! Listen, now—I told you I'd only made four prints of this photo, and that I knew exactly where they all were—one in my own album there, two given by James to friends in Bradford, one—as we more recently found out—given by James to Mrs. Marlow. That one—the Mrs. Marlow one—we believed to be—this—this!"
"And isn't it, Mr. Allerdyke?" asked Chettle wonderingly.
Allerdyke laughed—a laugh of relief and satisfaction.
"Less than an hour ago," he replied, "in fact, just before you came in, Mrs. Marlow showed me the photo which James gave her—showed it to me, out below there in the hall. No mistaking it! And so—when you came, I was racking my brains to rags trying to settle what this photo—this!—was. And now I know what it is—and damn me if I know whether the discovery makes things plainer or more mixed up! But—I know what this is, anyway."
"And—what is it, sir?" asked Chettle eagerly, eyeing the photo as if it were some fearful living curiosity. "What, Mr. Allerdyke?"
"Why, it's a photograph of my photograph!" almost shouted Allerdyke, with a thump of his big hand on the table. "That's the truth. This has been reproduced from mine, d'ye see? Look here—happen you don't know much about photography, but you'll follow me—I always use a certain sort of printing-out paper; I've stuck to one particular sort for years—all the photos in that album are done on that particular sort. The four prints I made of James's last photo were done on that paper. Now then—this photo, this print that you found in Lydenberg's watch, is not done on that paper—it's a totally different paper. Therefore—this is a reproduction! It is not my original print at all—it's been copied from it. See?"