Frémont’s map and geographical researches embrace the immense tract of land extending from the confluence of Kanzas River with the Missouri, to the cataracts of the Columbia and the Missions of Santa Barbara and Pueblo de los Angeles in New California, presenting a space amounting to 28 degrees of longitude (about 1360 miles) between the 34th and 45th parallels of north latitude. Four hundred points have been hypsometrically determined by barometrical measurements, and for the most part, astronomically: so that it has been rendered possible to delineate the profile above the sea’s level of a tract of land measuring 3,600 miles with all its inflections, extending from the north of Kanzas River to Fort Vancouver and to the coasts of the South Sea (almost 720 miles more than the distance from Madrid to Tobolsk). As I believe I was the first who attempted to represent, in geognostic profile, the configuration of entire countries, as the Spanish Peninsula, the highland of Mexico, and the Cordilleras of South America (for the half-perspective projections of the Siberian traveller, the Abbé Chappe,[O] were based on mere and for the most part on very inaccurate estimates of the falls of rivers); it has afforded me special satisfaction to find the graphical method of representing the earth’s configuration in a vertical direction, that is, the elevation of solid over fluid parts, achieved on so vast a scale. In the mean latitudes of 37° to 43° the Rocky Mountains present, besides the great snow-crowned summits, whose height may be compared to that of the Peak of Teneriffe, elevated plateaux of an extent scarcely to be met with in any other part of the world, and whose breadth from east to west is almost twice that of the Mexican highlands. From the range of the mountains, which begin a little westward of Fort Laramie, to the further side of the Wahsatch Mountains, the elevation of the soil is uninterruptedly maintained from five to upwards of seven thousand feet above the sea’s level; nay, this elevated portion occupies the whole space between the true Rocky Mountains and the Californian snowy coast range from 34° to 45° north latitude. This district, which is a kind of broad longitudinal valley, like that of the lake of Titicaca, has been named _The Great Basin_ by Joseph Walker and Captain Frémont, travellers well acquainted with these western regions. It is a _terra incognita_ of at least 8000 geographical (or 128,000 English) square miles, arid, almost uninhabited, and full of salt lakes, the largest of which is 3940 Parisian (or 4200 English) feet above the level of the sea, and is connected with the narrow Lake Utah,[P] into which the “Rock River” (_Timpan Ogo_ in the Utah language) pours its copious stream. Father Escalante, in his wanderings from Santa Fé del Nuevo Mexico to Monterey in New California, discovered Frémont’s “Great Salt Lake” in