"You do not seem to use it," said T. B.
"We are very tidy people," smiled the doctor; "and now you shall see the room below."
As they went down the stairs again they heard the curious wail, and T. B. experienced a tremulous jar which he had noted before.
"Unpleasant, is it not?" said Dr. Fall. "I was quite alarmed at that at first, but it has no unpleasant consequences."
On the second floor he entered the third room, immediately below that in which the sick Mr. Moole was lying. He unlocked this door and they entered a well-furnished bedroom; on a more elaborate scale than that which T. B. had seen before.
"This is our spare bedroom," said Dr. Fall, easily; "we seldom use it."
T. B. slipped into the apartment and made a quick scrutiny. There was nothing of a suspicious character here.
"I hope you are satisfied now," said Dr. Fall as he led the way out, "and that your two friends below are not growing impatient."
"You have seen them, then," said T. B.
"I have seen them," said the other gravely. "I saw them a few moments after you entered the hall. You see, Mr. Smith," he went on, "we do not employ anything so vulgar as bells to alarm us. When the entrance door opens, a red light shows above my bed. Unfortunately, the moment you came in I happened to be in an adjoining room at work. I had to go into my bedroom to get a paper, when I saw the light. So, though I am perhaps inaccurate in saying that I have been keeping you under observation from the moment you arrived, there was little you did which was not witnessed. I will show you, if you will be good enough to accompany me to my room."