“I can’t say I’m making much progress,” he admitted, finally, closing his note-book and taking from his wallet carefully the original crumpled sheet I had found in the scrap-basket. “There’s just one thing I’d like to try—not to decipher it, for that will take time, I see—but to see if there is anything else that I missed as I looked at it so hastily up there in that room.”
At the ice-water cooler, which never had any ice in it, nor cups about it, he held the sheet of paper for a moment under the tepid running water. Since he had first wet it, it had dried out and the figures were again invisible. Then he returned to our seat and soon was deep in the study of the original this time.
“I can say one thing,” he remarked, folding the cipher carefully so as not to tear the weakened fibers, as we rolled into the New York terminus, “the person who wrote that thing is a crook—has the instincts of a spy and traitor.”
“How do you know that?” I inquired.
“How?” he repeated, quietly, glancing up sharply from a final look at the thing. “Did you ever hear of the science of graphology—the study of character in handwriting? Much the same thing applies to figures. It’s all there in the way those figures are made, just as plain as the nose on your face, even if the meaning of the cipher is still hidden. We have a crook to deal with, and a very clever one, too, even if we don’t know yet who it is. It’s possible to hide a good deal, but not everything—not everything.”
From the station Kennedy and I went immediately down to the office of Hastings. It was still very early and few offices were occupied. Kennedy opened the door and, as I anticipated, went directly to the spot in the office where he had unearthed, or rather unwalled, the detectaphone transmitter.
There was not a chance that any one would be listening at the other end, yet he proceeded cautiously. The transmitter had been placed close to the plaster which had not been disturbed in Hastings’s office. So efficient was the little machine that even the plaster did not prevent sound waves from affecting its sensitive diaphragm.
“But how could it have been put in place?” I asked as Kennedy explored the hole he had made in the wall.
“That’s new plaster back there,” he pointed out, peering in. “Some one must have had access on a pretense to the next office and placed the transmitter that way, plastering up the wall again and painting it over. You see, Hastings wouldn’t know about that.”
“Still,” I objected, “any one going in and out of the next office would be likely to be seen. Who has the office?”