"The sunlight stayed there; and then the shadow came very slowly back, and there was no noise of the door being shut."
Bill looked at him with startled eyes.
"By Jove! You mean that Cayley closed the door afterwards as an afterthought—and very quietly—so that you couldn't hear?"
Antony nodded.
"Yes. That explains why I was surprised afterwards when I went into the room to find the door open behind me. You know how those doors with springs on them close?"
"The sort which old gentlemen have to keep out draughts?"
"Yes. Just at first they hardly move at all, and then very, very slowly they swing to— well, that was the way the shadow moved, and subconsciously I must have associated it with the movement of that sort of door. By Jove!" He got up, and dusted his knees. "Now, Bill, just to make sure, go in and close the door like that. As an afterthought, you know; and very quietly, so that I don't hear the click of it."
Bill did as he was told, and then put his head out eagerly to hear what had happened.
"That was it," said Antony, with absolute conviction. "That was just what I saw yesterday." He came out of the office, and joined Bill in the little room.
"And now," he said, "let's try and find out what
