"Oh, I wish John would hurry and catch up with us!" she exclaimed. "Please don't fall, Scylla--hang on to the pommel tight." Scylla, who had stopped crying, told Martha not to worry, that she would not fall; and the slow journey over the prairie continued silently for a minute or two. Every once in a while Martha turned back and looked toward the flickering camp-fire of the cow-boys. An exclamation of surprise was drawn from her when she failed to see it shining in the distance, and she stopped. Then, faintly, she heard shouts and the thumping of racing hoofs on the prairie. "John is coming at last," she said. But then she realized that more than one animal's hoofs were drumming desperately on the turf. While she stood wondering if some of the cow-boys were coming home with John, she heard the hoof-beats merge into a steady roar. Even the shouts of the men which she had just heard were drowned in this dull, threatening rumble. For just an instant she thought it was thunder, and then her quick reasoning told her the truth. The herd had stampeded! That she and Scylla were directly in its path she was certain, for the camp-fire had, a moment before, been between them and the herd and was now invisible. It had either been trampled out or was hidden by the advancing mass of cattle. [Illustration: "JUST THEN ANOTHER FLASH CAME AND SHOWED A COW-BOY LEANING FAR OVER THE NECK OF HIS PONY, RIDING FOR HIS LIFE."] Martha well knew what it meant to be in the path of a stampede; but, strangely enough, all her fear left her. She was puzzled, that was all. Had she been alone, she could easily have escaped by jumping on Dan's back and riding hard. Dan could have distanced the cattle, even when they were stampeding. But now she had helpless Scylla to take care of. The advancing thunder-clouds had wholly hidden the moon and put the prairie in inky darkness. At first Martha thought of starting Dan away with Scylla and trusting to Providence to keep the little invalid on his back, while she remained to face the danger alone; then she thought of trying to ride with her. But she knew Scylla could not possibly keep her place in the saddle of the horse while he ran, even if she herself should mount him too and try to hold Scylla on. She stepped back to Scylla's side. There was a deathly doubt in her heart as to whether she was doing the right thing; but she had made a desperate resolve. Scylla had heard the thunder of the approaching herd too, and was too frightened to speak. Martha held her arms up toward her just as the first flash of lightning came. "Come, Scylla," she said, "slide off into my arms. The herd has stampeded and is coming toward us, but I will try to save us both." Without a word Scylla did as she was told, and in a few seconds was half kneeling, half lying on the ground. Then Martha struck Dan as hard as she could with her flat hand. "Hey up, Dan!" said she, "run! run! _You_ needn't stay here, too!"