Suddenly the boy uttered an exclamation. "What is it?" demanded Bob, hastening over to the spot where Steve was pulling something from between the platform and the rock wall of the shaft. What he had found was a piece of plank from which two pieces had been split off. At the breaking point on each end they plainly saw the cut of a saw. "Well, what do you think of that?" muttered Bob. "Is that the plank that held up the post?" "Judging from the mark in the middle, I should say it was. Bring the old post over here." Bob did so, and at Steve's direction placed the end of the post on the broken piece of plank. The post fitted the faint outline perfectly. "Well, what do you think of that?" breathed Jarvis. "That somebody has tried to make a clean job of getting me out of the way. That plank was sawed partly through so that it might not break at once, but would do so when any extra weight was thrown upon it. We must find those other pieces, Bob. Look about. I guess we'll have something to report to Mr. Penton." Illustration: Steve Triumphantly Held Up a Saw. "Shall we say who did it?" "We can't really say. We may have our suspicions, but unless we get more evidence we shall have to let it go as it is. I have some facts in my possession that may help us, though." Steve got down on his hands and knees and began going over the floor with great thoroughness. He was keen and alert and his eyes glowed with resolute purpose. "Here's one of the broken pieces," cried Bob. "Good. See if you can find the other. We shall have our case complete in a few minutes if we keep on having such good luck." But one piece was all that Bob was able to find, the other no doubt having been thrown into the shaft. The one found was lying at the edge of the platform near its end. "I guess there is nothing more here for us to do," decided the lad finally. "We will take our evidence and go to Mr. Penton." "We haven't enough to hang a dead cat on." Steve smiled. "We shall see," he answered. "You tuck the saw under your coat and I will carry the boards." Entering the first cage that stopped at this level, the boys were quickly conveyed to the surface. Steve asked the cage-tender at the mouth of the shaft if he had seen the superintendent about the shaft, and was informed that Mr. Penton was at that moment in the dry house. He was no doubt dressing to go down in the mine. The boys hurried to the dry house, finding Mr. Penton talking with one of the time-checkers. "May we see you alone, sir?" asked Steve. "Certainly. Come into my dressing room. You have some news, eh?" queried the superintendent, flashing a keen glance at them. "We think we have, sir." After entering the dressing room, Mr. Penton nodded for them to proceed. Steve went right to the point. "We have been down in the skip shaft." "On seventeen platform?" "Yes, sir." "Did you discover anything of consequence?"