Lanky was forced to admit that his declaration was only grounded on certain suspicious circumstances. He would have told of Lef’s queer actions, but Frank declined to listen. “I’m going to try and find out the truth for myself, Lanky; but whatever I do, I won’t accuse any one until I can pin him down with indisputable proof,” he said. “And then what, Frank?” “Well, I won’t say, but the miserable coward who would try to strip a fellow of his reputation hadn’t ought to be allowed to go free,” and had Lef seen the flash in the eyes that accompanied these words, he would very likely have trembled more than ever, and tried to walk a chalk-line. Frank sought the principal after school. He found the professor in his office, and the other welcomed him with a warm smile. “What can I do for you, Frank? You understand that not for a single minute did I dream that you were guilty. I had remembered the circumstances of your being in my company every bit of the time while I was out of here, and the thief crept in to rob my desk. But I would give a good deal to be able to find out who played so mean a trick upon you.” “Will you let me see the paper you received, sir?” asked Frank. “That you will find in my waste-paper basket yonder. Now that you mention it, I can see that it was unwise of me to toss it aside contemptuously. Have you found it, my lad?” “Yes, sir,” said Frank, bending over. “I see, you think it possible to recognize the writing. But in this case the scoundrel followed the usual custom with all anonymous letter writers, for he simply printed the words,” remarked the principal. “Yes, sir, I notice he did. And the paper seems to be just what is used by every student in school, as the supplies come from you,” observed Frank, still examining the crumpled sheet. “I’m afraid that we may never know who did it, unless through some accident.” “Where did you find this note, sir?” continued the boy, eagerly, as though a sudden idea had struck him. “Slipped under my door here when I opened it this morning. You know Mr. Dolan does not open my office save on Saturdays, when he cleans. Whoever put the paper under the door chose a time when no one was likely to see him.” “You threw this in the basket as soon as you read it, sir?” “Yes, for, as I remarked, I was indignant,” replied the professor, curiously wondering what all these questions implied. “And at that early time I don’t suppose you were using your ink at all, sir?” “Certainly not, Frank. What makes you ask that, lad?” Frank spread the paper, which he had smoothed out, before the gentleman. “You see, sir, whoever wrote this used ink; and in some way or other he must have gotten a certain small amount on his fingers and thumb. Look here, and you will see where there is a very plain imprint of a thumb, and from the other marks that accompany it, I should say that it is the _left_ thumb, too!”