George was standing in the dry grass, with a great stone in each hand, as if he already knew their danger and was prepared; but when Coleman told him in hurried words what they had to expect, he dropped the stones, and they began to look about for a place of safety. It was not far to a high rock upon which they both scrambled, and then Bromley let himself down again, and passed up a number of angular stones for ammunition. Whatever the mysterious beast might be, they could keep him off from the rock for a time, but they were not prepared for a siege. They had little to say to each other, and that in whispers as they strained their eyes to look into the entrance to the cavern. Bromley, however, was softly humming a tune, and just as Coleman looked up at him in astonishment he dropped the stones from his hands and burst into laughter; and sure enough, there in the mouth of the cavern stood their tame bear, Tumbler, wagging his head from side to side just as Coleman had seen the mysterious eyes move in the darkness, and, moreover, he was still licking his chops after the feast he had made on the bats. Lieutenant Coleman had been so alarmed at first, and then so gratified at the happy outcome of his adventure, that he had not noticed the character of the stones which Bromley had been handling. It was not until his attention was called to a flake of mica that he looked about him on the ground, to see every where blocks and flakes of what is commonly called isinglass. They could have something better than wooden shutters for their windows now.