With a roar Thor launched himself among them. His great right arm swept out and inward, and it seemed to Muskwa that he had gathered a half of the pack under his huge body. With a single crunch of his jaws he broke the back of the foremost hunter. From a second he tore the head so that the windpipe trailed out like a red rope. He rolled himself forward, and before the remaining dogs could recover from their panic he had caught one a blow that sent him flying over the edge of the precipice to the rocks a hundred feet below. It had all happened in half a minute, and in that half-minute the remaining nine dogs had scattered. But Langdon's Airedales were fighters. To the last dog they had come of fighting stock, and Bruce and Metoosin had trained them until they could be hung up by their ears without whimpering. The tragic fate of three of their number frightened them no more than their own pursuit had frightened Thor. Swift as lightning they circled about the grizzly, spreading themselves on their forefeet, ready to spring aside or backward to avoid sudden rushes, and giving voice now to that quick, fierce yapping which tells hunters their quarry is at bay. This was their business--to harass and torment, to retard flight, to stop their prey again and again until their masters came to finish the kill. It was a quite fair and thrilling sport for the bear and the dogs. The man who comes up with the rifle ends it in murder. But if the dogs had their tricks, Thor also had his. After three or four vain rushes, in which the Airedales eluded him by their superior quickness, he backed slowly toward the huge rock beside which Muskwa was crouching, and as he retreated the dogs advanced. Their increased barking and Thor's evident inability to drive them away or tear them to pieces terrified Muskwa more than ever. Suddenly he turned tail and darted into a crevice in the rock behind him. Thor continued to back until his great hips touched the stone. Then he swung his head side wise and looked for the cub. Not a hair of Muskwa was to be seen. Twice Thor turned his head. After that, seeing that Muskwa was gone, he continued to retreat until he blocked the narrow passage that was his back door to safety. The dogs were now barking like mad. They were drooling at their mouths, their wiry crests stood up like brushes, and their snarling fangs were bared to their red gums. Nearer and nearer they came to him, challenging him to stay, to rush them, to catch them if he could--and in their excitement they put ten yards of open space behind them. Thor measured this space, as he had measured the distance between him and the young bull caribou a few days before. And then, without so much as a snarl of warning, he darted out upon his enemies with a suddenness that sent them flying wildly for their lives.