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