He did not lose another second in wondering whether it could be done. There was absolutely nothing else for him to try, if he hoped to keep from being slowly suffocated in that prison cell. He could do it, he _must_ do it! When he set to work, he found at once that the wood was inclined to be soft and wormy, especially close to the crack. Time had overcome the hardness of the oak, and under his vigorous assault it fairly crumbled away in sections. After what may have been a minute's labor but which seemed much longer, Bob was able to thrust his whole arm through the cleft he had made. At that rate he would soon be free. The very thought gave him new energy, and he went at the task even more fiercely than before. But somehow his rate of progress did not seem to increase in proportion to the extra vim he threw into the work. Evidently the deeper he cut, the harder the wood became. It was decayed only along the crevice! Realizing this, he now turned his attention to the other side, and for a brief time all went smoothly, progress being rapid. Now he could even thrust a leg out of his cell. Twice that dimension, and the gap would be large enough to admit of the passage of his entire body. But surely it was getting much hotter inside the stump. The fire had taken hold in earnest. He believed that the flames must be curling around the old tree, and mounting upward while they fed upon the dead wood. It mattered not just then that his hand grew sore from constant friction with the rough buck-horn handle of his knife. Such little things could not count when everything depended on his making a success of his effort. Just then Bob needed all the encouragement he could find. He realized this, and to try and cheer up his drooping spirits he started talking to himself while he worked, even laughing from time to time. It encouraged him, and could do no harm. "That was a good slice, Bob!" he went on, just as though it might be his mother speaking, "Keep it up, my boy! You're just bound to break out of this smoke-stack soon! Nothing can stop you, now you've got started in the right direction. Hey! almost dropped my knife outside that time. Gracious! what if it had gone beyond my reach! You must be more careful after this, Robert, my lad!" He sliced away, and the opening grew wider; but, oh! how slowly its dimensions increased, and how much hotter did the air seem all around him! Was it fated that he should be smothered here, suffocated by the pungent smoke that caught his breath, and seemed to choke him? He would not allow himself to give way to even the thought of such a horrible thing. "Sure you will get through, Bob!" he shouted, as he kept working away with every atom of strength. "Why, the hole must be mighty near big enough now for you to slip through. Sandy could do it, I know, and I'm not much stouter than he. Just hold out a little longer, boy! Keep at it, and success must come."