apartment from the janitor. After considerable difficulty, owing to the narrowness of the air-shaft, Kennedy managed to pick up the loose ends of the wire which had been led out of the little window at the base of the shaft, and had attached it to a couple of curious arrangements which he had brought with him. One looked like a large taximeter from a motor cab; the other was a diminutive gas-metre, in looks at least. Attached to them were several bells and lights.
He had scarcely completed installing the thing, whatever it was, when a gentle tap at the door startled me. Kennedy nodded, and I opened it. It was Carton.
"I have had my men watching the Mayfair," he announced. "There seems to be a general feeling of alarm there, now. They can't even find Loraine Keith. Brodie, apparently, has not shown up in his usual haunts since the episode of last night."
"I wonder if the long arm of this vice trust could have reached out and gathered them in, too?" I asked.
"Quite likely," replied Carton, absorbed in watching Kennedy. "What's this?"
A little bell had tinkled sharply, and a light had flashed up on the attachments to the apparatus.
"Nothing. I was just testing it to see if it works. It does, although the end which I installed down below was necessarily only a makeshift. It is not this red light with the shrill bell that we are interested in. It is the green light and the low-toned bell. This is a thermopile."
