The sitting-room of our client opened by a long, low, latticed window on to the ancient lichen-tinted court of the old college. A Gothic arched door led to a worn stone staircase. On the ground floor was the tutor’s room. Above were three students, one on each story. It was already twilight when we reached the scene of our problem. Holmes halted and looked earnestly at the window. Then he approached it, and, standing on tiptoe with his neck craned, he looked into the room.

“He must have entered through the door. There is no opening except the one pane,” said our learned guide.

“Dear me!” said Holmes, and he smiled in a singular way as he glanced at our companion. “Well, if there is nothing to be learned here, we had best go inside.”

The lecturer unlocked the outer door and ushered us into his room. We stood at the entrance while Holmes made an examination of the carpet.