“You interest me amazingly, my boy. And it is all just as you say. I do declare, it must be the left thumb that has left an imprint here. I see what you have in mind, Frank. Go your own way about it. If you discover the guilty one, I leave it to you entirely whether you bring him before me or not. This is your especial affair, and you can manage it as you please.” “Well, I happened to be reading lately how they take the imprint of criminals’ thumbs over in France, and that no two are exactly alike. With other measurements, it is called the Bertillon system, and has been found to work well. There, I have made an impression of my left thumb, and you can see, sir, that the lines are very much unlike this one.” “Frank, you are correct, and I give you credit for so much acumen. But do you want me to call every boy in school in here and take an impression of each left thumb, so that we can discover the one rascal?” smiled the principal. “Oh, no, sir, but I thought I’d like to try on my own hook, to see if I could land him,” exclaimed Frank. “All right, go ahead. I give you free permission, and wish you luck. And, Frank, perhaps you have already some idea as to what direction you mean to hunt first of all,” this last with uplifted eyebrows and a questioning look. “Well, sir,” said Frank, as he turned to depart with the precious paper safe in his pocket, “I suppose I have suspicions, but they may be unjust toward a certain party, and I wouldn’t mention them to any one. Thank you, Professor, for helping me. If I succeed, perhaps I may bring the proof to you. It all depends upon circumstances.” “Ah, yes,” murmured the professor, after he found himself alone; “I can understand what that means. If the rascal pleads only strong enough that generous lad will even go so far as to forgive him, and hush the ugly matter up, for the honor of Columbia. Would that there were more like him!” CHAPTER VII THE IMPRINT IN THE CLAY “I don’t believe in it, that’s all!” said Lanky Wallace, with a shake of his head. “Well, now, for my part, I’m not so hard to convince. Just because they look alike at first glance is no reason why it would be so if you put our hands under a magnifier. I kind of side with Frank,” observed Buster Billings. They were gathered in a group in the gymnasium, and chattering like magpies. A dozen or more boys had dropped in after school Thursday afternoon, as a drizzling rain prevented any outdoor work, and there were many temptations for lovers of athletics in that well equipped gym. “Do you mean to tell me,” burst out Lanky, with a look of scorn, “that everybody’s two hands differ, and that yours are entirely unlike mine. I just fail to see it, and I’m not the only one, either.” “That’s so,” remarked Jack Eastwick; “as for me, I side with Lanky. You’ll have to show me, Frank, before I’ll back down.”