“Do you know, Watson,” said Holmes as we sat together in the gathering darkness, “I have really some scruples as to taking you to-night. There is a distinct element of danger.”

“Can I be of assistance?”

“Your presence might be invaluable.”

“Then I shall certainly come.”

“It is very kind of you.”

“You speak of danger. You have evidently seen more in these rooms than was visible to me.”

“No, but I fancy that I may have deduced a little more. I imagine that you saw all that I did.”

“I saw nothing remarkable save the bell-rope, and what purpose that could answer I confess is more than I can imagine.”

“You saw the ventilator, too?”

“Yes, but I do not think that it is such a very unusual thing to have a small opening between two rooms. It was so small that a rat could hardly pass through.”

“I knew that we should find a ventilator before ever we came to Stoke Moran.”

“My dear Holmes!”

“Oh, yes, I did. You remember in her statement she said that her sister could smell Dr. Roylott’s cigar. Now, of course that suggested at once that there must be a communication between the two rooms. It could only be a small one, or it would have been remarked upon at the coroner’s inquiry. I deduced a ventilator.”

“But what harm can there be in that?”

“Well, there is at least a curious coincidence of dates. A ventilator is made, a cord is hung, and a lady who sleeps in the bed dies. Does not that strike you?”

“I cannot as yet see any connection.”

“Did you observe anything very peculiar about that bed?”