Doc Phone Line Tracer

To Long Tom, the electrical wizard, came the first commands.

Doc gave Long Tom the address of that tenth house in a row of dwellings that were all alike. He told the exact secret wall recess.

"I want you to trace that phone wire," Doc explained. "It was not installed by the regular telephone company. Kar must have put it in himself. It leads to some secret lair of Kar's. I want you to follow it to that lair."

"Sure," said Long Tom. "I'll use a--"

"I know what you'll use," Doc interposed. "The apparatus is right here in my laboratory. You can find it!"

Long Tom hurried into the great laboratory room. He selected two boxes. They were replete with vacuum tubes, dials and intricate coils. They might have been radio sets, because one was equipped with head phones. But they weren't.

One box held an apparatus which created a high-frequency electric current. When this current was placed upon a telephone wire, it would make no sound audible to the human ear. But it would throw an electrical field about the wire. This field extended a considerable distance.

The other box was an "ear" for detecting this field. Using it, Long Tom could walk about with the head phones upon his head. The phones would give a loud squeal when he brought the "ear" within proximity of the wire charged with his peculiar current.

The wire might be buried yards underground, but the "ear" would detect its presence anyway. Nor would brick walls interfere with the sensitive detector.

Long Tom hurried out with his equipment. He took a taxi for the tenth house in the row of similar houses uptown.

- The Land of Terror (1933) Chapter 8