For a time he examined the slips of paper bearing the various messages the boys had scribbled down and his forehead wrinkled in a frown of perplexity.
“It’s very indefinite,” he announced at last, half to himself, “but I agree with you that the whole matter has a suspicious appearance. Too bad you didn’t take down the earlier messages you heard. Now, let’s see. You say you have never heard the other party to the conversations and yet you have been listening in within a block of this chap. Very odd, yes, most extraordinary. There are several explanations that occur to me, however. For example, if they wished the conversation to be secret and unintelligible they might have arranged that one man was to talk through an ordinary phone and the other by radio. Or they might have arranged this because the second man had no sending set—exactly as you boys communicated with one
another with only one transmission set among you.”
“Gee, but we are dumb-bells!” exclaimed Tom. “Why the dickens didn’t we think of that? Why we are doing the same thing ourselves. It was so simple we overlooked it.”
Mr. Henderson smiled. “That’s often the way,” he declared. “During the war a lot of messages passed our censors as perfectly innocent and harmless and yet they were of the utmost importance—they were so frank and simple we overshot the mark.”
“Yes, Dad told us about some of those,” said Tom.
“As I was saying,” went on Mr. Henderson, “if one man was talking over a telephone you would not have heard him under ordinary conditions, but it often happens that through capacity inductance a phone message may come in over a radio set. That might account for your occasionally hearing those sounds which you describe as resembling words coming through a paper-covered comb. Do you remember the conditions under which you heard those sounds? Were you near telephone receivers,
touching any part of your sets or doing anything unusual?”
The boys thought deeply, trying to revisualize the conditions that had existed on the few occasions when they had heard the odd buzzing sounds.
“I’m not sure,” said Tom at last, “but it seems to me that when I heard them the first time—that time I was on 23d St., I was sitting close to the telephone receiver on the table—I’d just been called up by Jim and—yes, I am sure now, I remember distinctly—I had my hand touching the stand while I was listening to the messages. You see, I was half inclined to phone to the others to find out if they heard the sounds and I reached out to pick up the phone and then changed my mind—but sort of kept my hand there.”