"Now Ned," explained Tom, "the idea is this! You go into that booth, just as if it were a public one, and ring me up in the regular way. Of course we haven't a central here, but that doesn't matter. Now while I'm talking to you I want to see you. You don't know that, of course."
"The point is to see if I can get your picture while you're talking to me, and not let you know a thing about it."
"Think you can do it, Tom?"
"I'm going to try. We'll soon know. Go ahead."
A little later Ned was calling up his chum, as casually as he could, under the circumstances.
"All right!" called Tom to his chum. "Start in and talk. Say anything you like--it doesn't matter. I want to see if I can get your picture. Is the light burning in your booth?"
"Yes, Tom."
"All right then. Go ahead."
Ned talked of the weather--of anything. Meanwhile Tom was busy. Concealed in the booth occupied by Ned was a sending plate. It could not be seen unless one knew just where to look for it. In Tom's booth was a receiving plate.
The experiment did not take long. Presently Tom called to Ned that he need stay there no longer.