"The label, you observe, is the right way up as it hangs on the wall."
"So it is," I rejoined hastily, a little annoyed that I had not been quicker to observe so obvious a fact. "I see your point. You mean that the frame-maker hung the thing upside down and Jeffrey never noticed the mistake?"
"That is a perfectly sound explanation," said Thorndyke. "But I think there is something more. You will notice that the label is an old one; it must have been on some years, to judge by its dingy appearance, whereas the two mirror-plates look to me comparatively new. But we can soon put that matter to the test, for the label was evidently stuck on when the frame was new, and if the plates were screwed on at the same time, the wood that they cover will be clean and new-looking."
He drew from his pocket a "combination" knife containing, among other implements, a screw-driver, with which he carefully extracted the screws from one of the little brass plates by which the frame had been suspended from the nails.
"You see," he said, when he had removed the plate and carried the photograph over to the gasjet, "the wood covered by the plate is as dirty and time-stained as the rest of the frame. The plates have been put on recently."
"And what are we to infer from that?"
"Well, since there are no other marks of plates or rings upon the frame, we may safely infer that the photograph was never hung up until it came to these rooms."
"Yes, I suppose we may. But what then? What inference does that lead to?"
Thorndyke reflected for a few moments and I continued:
"It is evident that this photograph suggests more to you than it does to me. I should like to hear your exposition of its bearing on the case, if it has any."