Burke took the address and a little while later we went ashore.
I was not surprised when Kennedy proposed, as the next move, to revisit the cellar in the apartment next to Gaskell's house. But I was surprised at what he said, after we had reached the place.
All along I had supposed that he was planning to wait there in hope of catching the person who had installed the detectaphone. That, of course, was a possibility, still. But in reality he had another purpose, also.
We had scarcely secreted ourselves in the cellar storeroom, which was in a dark corner where one might remain unobserved even if the janitor entered the cellar, provided he did not search that part, when Kennedy took the receiving headpiece of the detectaphone and placed it over his head, quite as if nothing had happened.
"What's the use of that?" I queried. "You ripped the transmitter out up above."
He smiled quietly. "While my back was turned toward you, so that you couldn't see," he said, "I slipped the thing back again, only down further where Gaskell wouldn't be likely to find it, even if he looked. I don't know whether he was frank with us, so I thought I'd try the eavesdropping game myself, in place of the man who put this thing in in the first place, whoever he was."
We took turns listening, but could hear not a sound. Nor did anyone come into the cellar.
So a good part of the afternoon passed, apparently fruitless.
My patience was thoroughly exhausted when, suddenly, a motion from Craig revived my flagging interest. I waited impatiently for him to tell me what it was that he heard.
"What was it?" I asked finally as he pulled the receivers off his head and stood for a moment, considering.