“He said he’d call up and let you know as soon as he reached the place,” the telephone manager informed Tom.

There was nothing to do but wait, and meanwhile Tom did what he could to comfort Mrs. Damon.  She was quite nervous and inclined to be hysterical, and the youth thought it wise to have a cousin, who had come to stay with her, summon the doctor.

“But, Tom, what shall I do about those papers?” Mrs. Damon asked him.  “Shall I send them?”

“Indeed not!”

“But I want Mr. Damon restored to me,” she pleaded.  “I don’t care about the money.  He can make more.”

“Well, we’ll not give those scoundrels the satisfaction of getting any money out of you.  Just wait now, I’ll work this thing out, and find a way to catch that fellow.  If I could only think what that buzzing sound was—­”

Then, in a flash, it came to Tom.

“A sawmill!  A planing mill!” he cried.  “That’s what it was!  That fellow was telephoning from some place near a sawmill!”

The telephone rang in the midst of Tom’s excited comments.

“Yes—­yes!” he called eagerly.  “Who is it—­what is it?”

“This is Larsen—­the private detective you sent.”

“Oh, yes, you were at the drug store.”

“Yes, Mr. Swift.  Well, that party didn’t call up from here.”

“I know, Larsen.  It was from another station.  We’re after him.  Much obliged to you.  Come on back.”

Tom was sure his theory was right.  The man had called up the Damon house from some telephone near a sawmill.  And a little later Tom’s theory was proved to be true.  He got a report from the second detective.  Unfortunately the man had not been able to reach the telephone station before the unknown speaker had departed.

“Was the place near a sawmill?” asked Tom, eagerly.

“It was,” answered the detective over the wire.  “The telephone is right next door to one.  It’s an automatic pay station and no one seems to have noticed who the man was who telephoned.  I couldn’t get a single clue.  I’m sorry.”

“Never mind,” said Tom, as cheerfully as he could.  “I think I’m on the right track now.  I’m going to lay a trap for this fellow.”

CHAPTER XX

SETTING THE TRAP

Troublesome problems seemed to be multiplying for Tom Swift.  He admitted as much himself after the failure to capture the man who had telephoned to Mrs. Damon.  He had hoped that his plan of sending detectives to the location of the telephones would succeed.  Since it had not the youth must try other means.

“Now, Ned,” he said to his chum, when they were on their way from Mrs. Damon’s, it being impossible to do anything further there.  “Now, Ned, we’ve got to think this thing out together.”

“I’m willing, Tom.  I’ll do what I can.”

“I know you will.  Now the thing to do is to go at this thing systematically.  Otherwise we’ll be working around in a circle, and won’t get anywhere.  In the first place, let’s set down what we do know.  Then we’ll put down what we don’t know, and go after that.”