"Differing so much from the Atlantic side of our continent in coast, mountains, and rivers, the Pacific side differs from it in another most rare and singular feature--that of the Great interior Basin, of which I have so often spoken, and the whole form and character of which I was so anxious to ascertain. Its existence is vouched for by such of the American traders and hunters as have some knowledge of that region; the structure of the Sierra Nevada range of mountains requires it to be there; and my own observations confirm it. Mr. Joseph Walker, who is so well acquainted in those parts, informed that, from the Great Salt Lake west, there was a succession of lakes and rivers which have no outlet to the sea, nor any connection with the Columbia, or with the Colorado of the Gulf of California. He described some of these lakes as being large, with numerous streams, and even considerable rivers, falling into them. In fact, all concur in the general report of these interior rivers and lakes; and, for want of understanding the force and power of evaporation, which so soon establishes an equilibrium between the loss and supply of waters, the fable of whirlpools and subterraneous outlets has gained belief as the only imaginable way of carrying off the waters which have no visible discharge. The structure of the country would require this formation of interior lakes; for the waters which would collect between the Rocky Mountains and the Sierra Nevada, not being able to cross this formidable barrier, nor to get to the Columbia or the Colorado, must naturally collect into reservoirs, each of which would have its little system of streams and rivers to supply it. This would be the natural effect; and what I saw went to confirm it. The Great Salt Lake is a formation of this kind, and quite a large one; and having many streams, and one considerable river, four or five hundred miles long, falling into it. This lake and river I saw and examined myself; and also saw the Wahsatch and Bear River Mountains which inclose the waters of the lake on the east, and constitute, in that quarter, the rim of the Great Basin. Afterwards, along the eastern base of the Sierra Nevada, where we traveled for forty-two days, I saw the line of lakes and rivers which lie at the foot of that Sierra; and which Sierra is the western rim of the Basin. In going down Lewis's Fork and the main Columbia, I crossed only inferior streams coming in from the left, such as could draw their water from a short distance only; and I often saw the mountains at their heads, white with snow; which, all accounts said, divided the waters of the _desert_ from those of the Columbia, and which could be no other than the range of mountains which form the rim of the Basin on its northern side. And in returning from California along the Spanish trail, as far as the head of the Santa Clara Fork of the Rio Virgen, I crossed only small streams making their way south to the Colorado, or lost in sand--as