He moved the thing about. "Now, when the device comes near metal-piping, for example, or a wire, the balance is disturbed and I hear a sound. That was the gas pipe. It is easy to find its exact location. Hulloa—"
He paused again in a corner, back of Gaskell's desk and appeared to be listening intently.
A moment later he was ruthlessly breaking through the plaster of the beautifully decorated wall.
Sure enough, in there was a detectaphone, concealed only a fraction of an inch beneath the paper, with wires leading down inside the partition in the direction of the cellar.
CHAPTER XI
THE INFERNAL MACHINES
He ripped the little mechanical eavesdropper out, wires and all, but he did not disconnect the wires, yet.
We traced it out, and down into the cellar the wires led, directly, and then across, through a small opening in the foundations into the next cellar of an apartment house, ending in a bin or storeroom.
In itself the thing, so far, gave no clew as to who was using it or the purpose for which it had been installed. But it was strange.