“When I approached your room, I examined the window. You amused me by supposing that I was contemplating the possibility of someone having in broad daylight, under the eyes of all these opposite rooms, forced himself through it. Such an idea was absurd. I was measuring how tall a man would need to be in order to see, as he passed, what papers were on the central table. I am six feet high, and I could do it with an effort. No one less than that would have a chance. Already you see I had reason to think that, if one of your three students was a man of unusual height, he was the most worth watching of the three.

“I entered, and I took you into my confidence as to the suggestions of the side table. Of the centre table I could make nothing, until in your description of Gilchrist you mentioned that he was a long-distance jumper. Then the whole thing came to me in an instant, and I only needed certain corroborative proofs, which I speedily obtained.