From the intro: "The Colorado River of the West is formed in southeastern Utah by the junction of the Grand and Green rivers. For hundreds of miles it flows through a series of profound chasms, in many places from 4,000 to 6,000 feet deep, and rising nearly vertically for a considerable distance above the water. These canons are from one to fifteen miles wide at the top. The most famous of them is the Marble-Grand canon (really continuous, although it goes under two names, the Marble and the Grand). Through this vast gorge the Colorado drops 2,330 feet in 283 miles, the current sometimes attaining a velocity of twenty-five miles an hour. The river itself varies in width from seventy-five feet to a quarter of a mile. In the narrowest places it has at times a depth of over 100 feet. Up to 1869 practically nothing was known of the Colorado River from its source to where it emerges into the valley of the Grand Wash, except what could be observed from look-out points at the tops of the canons, or from the few places where descents had been made to the bottom. It was a river of mystery and of fear. For long distances it was supposed to flow underground. There was no evidence that any human being had ever passed through the canons and come out alive. The Indians who lived in the neighborhood considered such a feat preposterous. Then came a scientist and a man of nerve, Major John Wesley Powell, who studied the river carefully at several points along its bank, and calmly decided to risk his life in clearing up the mystery by navigating the stream clear through to the Wash. The undertaking was all the more remarkable from the fact that Powell had only one arm. He had lost his right arm in the battle of Shiloh. His plucky young wife, to whom he had been married but a month, was present at headquarters when he was wounded, and promptly offered herself as a substitute for the missing limb so that her husband could continue in service. She then and there enlisted, and General Grant gave her a "perpetual pass" to follow the army in the capacity she had chosen. With this help Major Powell continued in active service to the close of the war.""