Madly did he climb upward, and never would he forget the sight that met his eyes while making for that promised haven of refuge. As far as he could see, both to the east and to the west, that bank of leaping roaring flame held sway. Once Bob had been taken down to the sea by his father, and he had never forgotten how the great waves came sweeping resistlessly on, to break with a crash on the shore. So, in his mind, appeared those onrolling billows of fire. He could hardly breathe now. That was because of the heat and smoke combined. A great fear possessed him that perhaps after he had reached this dark cleft in the tree he might find it utterly impossible to push his way past the guarding portals. In that case all was lost, and he need not even mind dropping back to the ground, for the end would find him where he was. But at least that fear was quickly laid to rest. "It's plenty big enough!" he cried aloud in his new delight, for the opening was now only a couple of feet away from his hands. After that all he had to do was to cram his body through the hole, and find the shelter he craved. "Hurrah!" Somehow he could not help giving vent to that boyish shout at the prospect of cheating the fire out of its anticipated prey, although he really had little breath to spare just then. He even fixed it in his mind just how he must first of all thrust his lower limbs through the opening, and then allow himself to slide downwards, for he could already see that the hole extended toward the earth. It was not the first time Bob Armstrong found his nice little calculations upset by circumstances utterly beyond his control. Perhaps it would not be the last, either, since he expected to spend the major portion of his life roving the wilderness, in search of game, and in such labor as became a true pioneer. Just as Bob reached the hole in the tree he became conscious of the fact that the old stump was being violently agitated, as though some one were climbing up below him. He even glanced down, filled with a dread lest Sandy had after all disobeyed, and chased after him. Then something else attracted his attention and he raised his eyes, to make a most unpleasant discovery. The hole in the tree was no longer vacant, but a bristling black head and a pair of very frightened eyes met his startled gaze! CHAPTER XVII A STRANGE PRISON THE bear looked at Bob; and Bob stared at the bear. It was a mutual surprise, though on the whole, perhaps, the animal was the more astonished, since up to this time he could not have had any inkling of the tremendous things that were occurring so near his home. He blinked his little eyes as the glare of the great conflagration dazzled his vision; but at the same time there was not the faintest indication that Mr. Bruin thought of dropping back into his snug retreat.