“Yes, a sort of mouse-trap.  I’m glad my photo telephone is now perfected, Ned.”

“What has that got to do with it?”

“That’s going to be my trap, Ned.  Here is my game.  You know this fellow—­this strange unknown—­is going to call up Mrs. Damon to-morrow.  Well, I’ll be ready for him.  I’m going to put in the booth where he will telephone from, one of my photo telephones—­that is, the sending apparatus.  In Mrs. Damon’s house, attached to her telephone, will be the receiving plate, as well as the phonograph cylinder.”

“When this fellow starts to talk he’ll be sending us his picture, though he won’t know it, and we’ll be getting a record of his voice.  Then we’ll have him just where we want him.”

“Good!” cried Ned.  “But, Tom, there’s a weak spot in your mouse-trap.”

“What is it?”

“How are you going to know which telephone the unknown will call up from?  He may go to any of a hundred, more or less.”

“He might—­yes.  But that’s a chance we’ve got to take.  It isn’t so much of a chance, though when you stop to think that he will probably go to some public telephone in an isolated spot, and, unless I’m much mistaken he will go to a telephone near where he was to-day.  He knows that was safe, since we didn’t capture him, and he’s very likely to come back.”

“But to make the thing as sure as possible, I’m going to attach my apparatus to a number of public telephones in the vicinity of the one near the sawmill.  So if the fellow doesn’t get caught in one, he will in another.  I admit it’s taking a chance; but what else can we do?”

“I suppose you’re right, Tom.  It’s like setting a number of traps.”

“Exactly.  A trapper can’t be sure where he is going to get his catch, so he picks out the place, or run-way, where the game has been in the habit of coming.  He hides his traps about that place, and trusts to luck that the animal will blunder into one of them.”

“Criminals, to my way of thinking, are a good bit like animals.  They seem to come back to their old haunts.  Nearly any police story proves this.  And it’s that on which I am counting to capture this criminal.  So I’m going to fit up as many telephones with my photo and phonograph outfit, as I can in the time we have.  You’ll have to help me.  Luckily I’ve got plenty of selenium plates for the sending end.  I’ll only need one at the receiving end.  Now we’ll have to go and have a talk with the telephone manager, after which we’ll get busy.”

“You’ve overlooked one thing, Tom.”

“What’s that, Ned?”

“Why, if you know about which telephone this fellow is going to use, why can’t you have police stationed near it to capture him as soon as he begins to talk?”

“Well, I did think of that, Ned; but it won’t work.”

“Why not?”

“Because, in the first place this man, or some of his friends, will be on the watch.  When he goes into the place to telephone there’ll be a look-out, I’m sure, and he’d either put off talking to Mrs. Damon, or he’d escape before we had any evidence against him.”