Until comparatively lately that portion of the United States in which I have laid this story was wholly unexplored. The marvellous cañons of the Colorado River extend through a country absolutely bare and waterless, and save the tales told by a few hunters or gold-seekers who, pressed by Indians, made the descent of some of them, but little was known regarding this region. It was not until 1869 that a thorough exploration of the cañons was made by a government expedition under the command of Major Powell. This expedition passed through the whole of the cañons, from those high up on the Green River to the point where the Colorado issues out on to the plains. Four years were occupied by the party in making a detailed survey of the course of the main river and its tributaries. These explorations took place some eight or nine years after the date of my story. The country in which the Big Wind River has its source, and the mountain chains contained in it, were almost unknown until, after the completion of the railway to California, the United States government was forced to send an expedition into it to punish the Indians for their raids upon settlers in the plains. For details of the geography and scenery I have relied upon the narrative of Mr. Baillie-Grohman, who paid several visits to the country in 1878 and the following years in quest of sport, and was the first white man to penetrate the recesses of the higher mountains. At that time the Indians had almost entirely deserted the country. For the details of the dangers and difficulties of the passage through the cañons I am indebted to the official report of Major Powell, published by the United States government.