"So I see," admitted Happy Harry, and he spoke with some culture. "If you don't mind," he went on, "would you just as soon move that gun a little? It's pointing right at my head, and it might go off." "It is going off--very soon!" exclaimed Tom grimly, and the tramp started in alarm. "Oh, I'm not going to shoot you," continued the young inventor. "I'm going to fire this as an alarm, and the engineer will come in here and tie you up. Then I'm going to hand you over to the police. This rifle is a repeater, and I am a pretty good shot. I'm going to fire once now, to summon assistance, and if you try to get away I'll be ready to fire a second time, and that won't be so comfortable for you. I've caught you, and I'm going to hold on to you until I get that model and those papers back." "Oh, you are, eh?" asked the burglar calmly. "Well, all I've got to say is that you have grit. Go ahead. I'm caught good and proper. I was foolish to come in here, but I thought I'd take a chance." "Who are you, anyhow? Who are the men working with you to defraud my father of his rights?" asked Tom somewhat bitterly. "I'll never tell you," answered the burglar. "I was hired to do certain work, and that's all there is to it. I'm not going to peach on my pals." "We'll see about that!" burst out Tom. Then he noticed that a dining-room window behind where the burglar was kneeling was open. Doubtless the intruder had entered that way, and intended to escape in the same manner. "I'm going to shoot," announced Tom, and, aiming his rifle at the open window, where the bullet would do no damage, he pressed the trigger. He noticed that the burglar was crouching low down on the floor, but Tom thought nothing of this at the time. He imagined that Happy Harry--or whatever his name was--might be afraid of getting hit. There was a flash of fire and a deafening report as Tom fired. The cloud of smoke obscured his vision for a moment, and as the echoes died away Tom could hear Mrs. Baggert screaming in her room. "It's all right!" cried the young inventor reassuringly. "No one is hurt, Mrs. Baggert!" Then he flashed his light on the spot where the burglar had crouched. As the smoke rolled away Tom peered in vain for a sight of the intruder. Happy Harry was gone! Holding his rifle in readiness, in case he should be attacked from some unexpected quarter, Tom strode forward. He flashed his light in every direction. There was no doubt about it. The intruder had fled. Taking advantage of the noise when the gun was fired, and under cover of the smoke, the burglar had leaped from the open window. Tom guessed as much. He hurried to the casement and peered out, at the same time noticing the cut wire of the burglar alarm. It was quite dark, and he fancied he could hear the noise of some one running rapidly. Aiming his rifle into the air, he fired again, at the same time crying out: "Hold on!"