"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.
"What happened was this. This young fellow had employed his afternoon at the athletic grounds, where he had been practising the jump. He returned carrying his jumping shoes, which are provided, as you are aware, with several sharp spikes. As he passed your window he saw, by means of his great height, these proofs upon your table, and conjectured what they were. No harm would have been done had it not been that as he passed your door he perceived the key which had been left by the carelessness of your servant. A sudden impulse came over him to enter and see if they were indeed the proofs. It was not a dangerous exploit, for he could always pretend that he had simply looked in to ask a question.
"Well, when he saw that they were indeed the proofs, it was then that he yielded to temptation. He put his shoes on the table. What was it you put on that chair near the window?"
"Gloves," said the young man.
Holmes looked triumphantly at Bannister. "He put his gloves on the chair, and he took the proofs, sheet by sheet, to copy them. He thought the tutor must return by the main gate, and that he would see him. As we know, he came back by the side gate. Suddenly he heard him at the very door. There was no possible escape. He forgot his gloves, but he caught up his shoes and darted into the bedroom. You observe that the scratch on that table is slight at one side, but deepens in the direction of the bedroom door. That in itself is enough to show us that the shoe had been drawn in that direction and that the culprit had taken refuge there. The earth round the spike had been left on the table, and a second sample was loosened and fell in the bedroom. I may add that I walked out to the athletic grounds this morning, saw that tenacious black clay is used in the jumping-pit, and carried away a specimen of it, together with some of the fine tan or sawdust which is strewn over it to prevent the athlete from slipping. Have I told the truth, Mr. Gilchrist?"
The student had drawn himself erect.
"Yes, sir, it is true," said he.
"Good heavens, have you nothing to add?" cried Soames.
"Yes, sir, I have, but the shock of this disgraceful exposure has bewildered me. I have a letter here, Mr. Soames, which I wrote to you early this morning in the middle of a restless night. It was before I knew that my sin had found me out. Here it is, sir. You will see that I have said, `I have determined not to go in for the examination. I have been offered a commission in the Rhodesian Police, and I am going out to South Africa at once."'
"I am indeed pleased to hear that you did not intend to profit by your unfair advantage," said Soames. "But why did you change your purpose?"
Gilchrist pointed to Bannister.
"There is the man who set me in the right path," said he.
"Come now, Bannister," said Holmes. "It will be clear to you from what I have said that only you could have let this young man out, since you were left in the room, and must have locked the door when you went out. As to his escaping by that window, it was incredible. Can you not clear up the last point in this mystery, and tell us the reasons for your action?"