"I thought he meant to-day," said Quarles.
"No one has entered the house to-day," I answered.
"Yet, if Greaves was murdered, some one must have gained access to this room somehow, in spite of the locked door and fastened window."
"You have dropped the idea of the supernatural, then?"
"I am keeping an open mind."
"Shall we give it up and go, Professor?"
"Certainly not. I am supposed to be alone in the house, so we will await events. On the other side of that wall where the glass hangs is No. 5, I suppose?"
"Yes."
"That is the boarding-house. Keep still a minute while I get an idea of the furniture against this opposite wall. Randall said a man and his four daughters lived at No. 9, didn't he?"
I whispered an affirmative, and could dimly see the professor going slowly along the wall. He began tapping things, apparently with a pocket knife.