instruments indicated that fact. He tested the degree of variation
by passing the current first through the room and then through a
sensitive crystal to a delicate telephone receiver. There was a
distinct change in the buzzing sound heard through the telephone
when the room was occupied or unoccupied. What I have done is to
wind single loops of plain wire on each side of that room down
there, as well as to wind around the room a few turns of concealed
copper wire. These collectors are fitted to a crystal of
carborundum and a telephone receiver."

We had each tried the thing and could hear a distinct buzzing in
the receiver.

"The presence of a man or woman in that room would be evident to a
person listening miles away," he went on. "A high-frequency
current is constantly passing through that storeroom. That is what
causes that normal buzzing."

It was verging on midnight when Kennedy suddenly cried: "Here,
Walter, take this receiver. You remember how the buzzing sounded.
Listen. Tell me if you, too, can detect the change."

I clapped the receiver quickly to my ear. Indeed I could tell the
difference. In place of the load buzzing there was only a mild
sound. It was slower and lower.

"That means," he said excitedly, "that some one has entered that
pitch-dark storeroom by the broken window. Let me take the
receiver back again. Ah, the buzzing is coming back. He is leaving
the room. I suppose he has found the electric light cane and the