The width of the Missouri river at St. Charles, is 550 yards. Its alluvial banks however are insecure, and are not unfrequently washed away for many yards at its annual floods. The bed of its channel is also precarious, and is elevated or depressed by the deposition or removal of its sandy foundation. Hence the elevation or depression of the surface of this river, affords no criterion of its depth, or of the volume of water it discharges at any one period. Undulatory motions, like the boiling of a pot, are frequently seen on its surface, caused by the shifting of the sand that forms its bed. The volume of water it ordinarily discharges into the Mississippi is vastly disproportionate to its length, or the number and size of its tributaries. I have seen less than six feet depth of water at St. Charles at a low stage, and it was once forded by a soldier, at Bellefontaine, four miles above its junction with the Mississippi. Evaporation takes up large quantities, but absorption throughout the porous soil of its wide bottoms consumes much more. In all the wells dug in the bottom lands of the Missouri, water is always found at the depth of the surface of the river, and invariably rises or sinks with the floods and ebbings of the stream. Volumes of sand frequently enter these wells as the river rises. Its periodical floods deserve notice. Ordinarily this river has three periods of rising and falling each year. The first rise is caused by the breaking up of winter on the Gasconade, Osage, Kansau, Chariton, Grand, and other branches of the lower Missouri, and occurs the latter part of February, or early in March. Its second rise is usually in April, when the Platte, Yellow Stone, and other streams pour into it their spring floods. But the flood that more usually attracts attention takes place from the 10th to the 25th of June, when the melting snows on the Chippewan mountains pour their contents into the Missouri. This flood is scarcely ever less than five, nor more than 20 feet at St. Louis, above the ordinary height of the river. On two occasions, however, since the country was known to the French, it has arisen to that height in the Mississippi as to flow over the American Bottom in Illinois, and drive the inhabitants of Cahokia and Kaskaskia from their villages to the bluffs. Rain in greater or less quantities usually falls during the rise of the river, and ceases when the waters subside. So uniform is this the case in Upper Missouri, the region beyond the boundary of the State, that the seasons are divided into wet and dry. Pumice stones and other volcanic productions occasionally float down its waters.