He was up the farther hillside and out of sight before the bull worked himself up to a charge. Then Calhoun suddenly remembered one of the items in the data about cattle he'd looked into just the other day. He felt himself grow pale. "Murgatroyd!" he said sharply. "We've got to catch up! Fast! Stay with me if you can, but--" he was jog-trotting as he spoke--"even if you get lost I have to hurry!" He ran fifty paces and walked fifty paces. He ran fifty and walked fifty. He saw her, atop a rolling of the ground. She came to a full stop. He ran. He saw her turn to retrace her steps. He flung off the safety of the blast-rifle and let off a roaring blast at the ground for her to hear. Suddenly she was fleeing desperately, toward him. He plunged on. She vanished down into a hollow. Horns appeared over the hillcrest she'd just left. Cattle appeared. Four, a dozen fifteen, twenty! They moved ominously in her wake. He saw her again, running frantically over another upward swell of the prairie. He let off another blast to guide her. He ran on at top speed with Murgatroyd trailing anxiously behind. From time to time Murgatroyd called "_Chee-chee-chee!_" in frightened pleading not to be abandoned. More cattle appeared against the horizon. Fifty or a hundred. They came after the first clump. The first group of a bull and his harem were moving faster, now. The girl fled from them, but it is the instinct of beef-cattle on the open range--Calhoun had learned it only two days before--to charge any human they find on foot. A mounted man to their dim minds is a creature to be tolerated or fled from, but a human on foot is to be crushed and stamped and gored. Those in the lead were definitely charging now, with heads bent low. The bull charged furiously with shut eyes, as bulls do, but the cows, many times more deadly, charged with their eyes wide open and wickedly alert, and with a lumbering speed much greater than the girl could manage. She came up over the last rise, chalky-white and gasping, her hair flying, in the last extremity of terror. The nearest of the pursuing cattle were within ten yards when Calhoun fired from twenty yards beyond. One creature bellowed as the blast-bolt struck. It went down and others crashed into it and swept over it, and more came on. The girl saw Calhoun now, and ran toward him, panting. He knelt very deliberately and began to check the charge by shooting the leading animals. He did not succeed. There were more cattle following the first, and more and more behind them. It appeared that all the cattle on the plain joined in the blind and senseless charge. The thudding of hoofs became a mutter and then a rumble and then a growl.