Take to the Hills! The rider galloped at top speed down the hill and on into the valley, through the pouring rain. 'The dam is going!' A few residents of Johnstown, Pennsylvania, took the rider's advice —and lived. Thousands of people, however, either never got the rider's message or chose to disregard it. Many of those who didn't heed the warning paid with their lives. The citizens of Johnstown in 1889 had good reason for ignoring the advice. Once a year the old South Fork Dam seemed about to burst. The cry, 'Take to the hills.' had become an annual false alarm. This time, however, the rider's warning should have been taken in earnest. The rider was John G. Parke, a civil engineer who was in charge of the dam. The Great South Fork Dam was a huge earthen dike holding back the waters of an artificial lake. The dam had been constructed without any stone or cement. It had been built by piling up layer upon layer of soil, until the dam was 100 feet high. It was 90 feet wide at its base. The dam had passed through the hands of a series of owners. In recent years the dam and the lake behind it had been bought by a group of millionaires. The millionaires called themselves the Great South Fork Fishing and Hunting Club. They spent thousands of dollars stocking the lake with fish. They also added screens to pr the fish from getting out through the dam's drainage holes. Fishing was good, and the lake had never been higher than that spring of 1889. May had been an unusually rainy month. The streets in the lower parts of Johnstown were already flooded with six feet of water. Behind the dam, the lake had been rising at the rate of one foot per hour. The owners of the fishing club sent workers to pile more dirt on top of the dam to keep it from overflowing. The owners also ordered the workers to remove the screens, which had become jammed with fish, sticks, and other debris. The workers tried hard to clear the jam, but John Parke's trained engineer's eye could see that their efforts would be useless. Parke saddled a horse and began his ride through the valley warning people of the arriving floodwater. The rain continued to pour. At noon, the water washed over the top of the dam. Almost immediately a big notch developed in the top of the dike. Then, according to witnesses, the whole dam simply disappeared. One minute there was a dam, and the next minute —nothing. The lake moved into the valley like a living thing. In little more than half an hour, the dam emptied completely, sending 45 billion gallons of water down the valley toward Johnstown. A wave of water reaching 125 feet high raced toward the city, leaping forward at the rate of 22 feet per second. The huge wall of water approached East Conemaugh, a suburb of Johnstown. As it did, railroad engineer John Hess looked up from the string of freight cars his locomotive was pushing. He saw the water bearing down on him, now moving at 50 miles per hour. Hess moved the locomotive's throttle to wide open. Still pushing a string of freight cars before him, he raced the advancing flood into East Conemaugh. Hess tied down the locomotive's whistle, and its screaming blast preceded the train into the village. Johnstown was a railroad city. People in the whole Johnstown area knew that a tied-down whistle could only mean a disaster. And the already flooded streets told them what kind of disaster it was. Many people who had ignored earlier warnings now headed for the hills. Unable to reach the center of Johnstown, railroader Hess jumped from the locomotive cab in East Conemaugh, ran into his house, and roused his family. The Hesses made their way up the side of a hill just before the flood hit the village. As the great tumbling hill of water roared on toward the center of Johnstown, it ran into the East Conemaugh rail yard. In the yard was a roundhouse (机车库) contain