The Missouri, which we have shown to be the principal stream, rises in the Chippewan, or Rocky mountains in latitude 44° north, and longitude about 35° west from Washington city. It runs a northeast course till after it receives the Yellow Stone, when it reaches past the 48° of latitude, thence an east, then a south, and finally a southeastern course, until it meets the current of the Mississippi, 20 miles above St. Louis, and in latitude 38° 45' north. Besides numerous smaller streams, the Missouri receives the Yellow Stone and Platte, which of themselves, in any other part of the world, would be called large rivers, together with the Sioux, Kansau, Grand, Chariton, Osage, and Gasconade, all large and navigable rivers. Its length, upon an entire comparative course, is 1870 miles, and upon a particular course, about 3000 miles. Lewis and Clark make the distance from the Mississippi to the great falls, 2580 miles. There are several things in some respects peculiar to this river, which deserve notice. 1. Its current is very rapid, usually at the rate of four or five miles an hour, when at its height; and it requires a strong wind to propel a boat with a sail against it. Steam overcomes its force, for boats ply regularly from St. Louis to the towns and landings on its banks within the borders of the state, and return with the produce of the country. Small steamboats have gone to the Yellow Stone for furs. Owing to the shifting of its current, and its snags and sand-bars, its navigation is less safe and pleasant than any other western river, but these difficulties are every year lessened by genius and enterprise. 2. Its water is always turbid, being of a muddy, ash color, though more so at its periodical rise than at other times. This is caused by extremely fine sand, received from the neighborhood of the Yellow Stone. During the summer flood, a tumbler of water taken from the Missouri, and precipitated, will produce about one fourth of its bulk in sediment. This sediment does not prevent its habitual use by hundreds who live on its banks, or move in boats over its surface. Some filtrate it, but many more drink it, and use it for culinary purposes, in its natural state. When entirely filtrated, it is the most limpid and agreeable river water I ever saw. Its specific gravity then, is about equal to rain water; but in its turbid state, it is much heavier than ordinary river water, for a boat will draw three or four inches less in it than in other rivers, with the same lading, and the human body will swim in it with but very little effort. It possesses some medicinal properties. Placed in an open vessel and exposed to the summer's sun, it remains pure for weeks. Eruptions on the skin and ulcerous sores are cured by wading or frequent bathings, and commonly it produces slight cathartic effects upon strangers upon its first use.