OF THE MISSISSIPPI, MISSOURI, AND OHIO RIVERS
I trust it will not be deemed improper on this occasion, to offer a few remarks upon the character of these rivers, embracing more particularly the condition of their navigation.
The causes heretofore alleged as giving occasion to a diversity of soil within the valleys of the western rivers, have an effect also in giving character to their channels or beds. For example: the banks near the mouths of the rivers, being composed of a fine unctuous and adhesive alluvion, are less liable to crumble and wash away, and constitute a more permanent barrier to resist the force of the current, than those {258} higher up, that are composed of coarser materials. In consequence, the beds of the rivers are rendered narrower and deeper towards their mouths than at greater distances above them. This is more particularly the case with the Mississippi, Red, Arkansa, and some others, whose beds or channels gradually dilate, and become more shoal on ascending from their mouths. Thus it happens also, that the navigation of the Mississippi has fewer obstructions between Natches and its mouth than above this part of the river, having so great a depth of water, that mags, bars, &c. are sunk below the reach of any kind of water-craft employed in its navigation. From Natches upward to its confluence with the Missouri, the river presents impediments that become more and more numerous and difficult to pass. Still, however, the main channel, though intricate in many places, affords a sufficient depth of water in all stages for boats of five or six feet draft to ascend to the mouth of the Ohio. From this point to the Missouri, a distance of more than two hundred and twenty miles, the navigation is partially obstructed, during a very low stage of the water, by shoals, so that it is navigable only for boats of moderate burthen, requiring but about three feet of water. At the distance of about thirty miles above the mouth of the Ohio there are two rocky bars extending across the Mississippi, called the Big and Little Chains, which in the deepest channel across them afford no more than five or six feet of water in a low stage, and occasion a great rapidity of current. The Mississippi is usually at its lowest stage about the middle of August, the summer freshet of the Missouri having subsided previously to that time. It usually continues in this stage till it is swollen by the fall freshet of the Ohio, after which it subsides again, and remains low during the winter. The distance from New Orleans to the mouth of the Missouri is estimated at about twelve hundred miles; its current in the main channel of {259} the river is supposed to have an average velocity of three miles and three quarters per hour, in a moderate stage of the water; but when the river is high its velocity is considerably accelerated. Its water is turbid, being charged with a fine argillaceous mud, of a light colour, derived exclusively from the Missouri.
The Missouri is a very wild and turbulent river, possessing the ruder features of the Mississippi, but destitute of the gentleness characteristic of the latter in many places. The obstructions to the navigation of the Missouri, although they are of the same character with those of the Mississippi, are far more numerous and formidable than those of the latter. The channel is rendered exceedingly intricate by means of sand-bars and islands, and the navigation in many places is very hazardous, on account of the multiplicity of rafts, mags, sand-bars, &c. with which the channel is beset. No part of the river is exempt from these obstructions for any considerable distance, particularly when the water is low.
As this river in connexion with some of its principal tributaries traverses a considerable variety of climates, embracing more than ten degrees of latitude, a succession of spring freshets invariably takes place, and maintains an elevated stage of water from the breaking up of winter early in March, to the middle, and sometimes the last of July, when the summer freshet, yielded by the most northerly of its tributaries, takes place. During this period there is a sufficient depth to admit boats of almost any burthen; but during the residue of the year it can hardly be called navigable, except for boats drawing no more than twenty-five or thirty inches. The river is usually blocked up with ice during the winter season. The average velocity of its current, in a middling stage of water, may be estimated at four miles and one third. In time of a high freshet it moves with an {260} accelerated velocity, equal to five or five and half miles per hour.
The Ohio river, as before hinted, differs from those just described, in the rapidity of its current, the width of its bed, the character of its channel, and in several other respects; but as its general character is well known, a few remarks in relation to it will here suffice. The obstructions to its navigation are sand-bars, some few rafts and mags, and rapids, to which the intricacy of its channel in several places may be added. During a middle and high stage of water, the obstructions entirely disappear, and an accelerated current is the only difficulty to be encountered. The average velocity of the current, in a moderate stage of water, may be estimated at two miles and a half, and in a high stage, at three miles per hour. The season in which the navigation of the Ohio can be relied on, commences between the middle of February and first of March, and continues to the latter part of June. A fall freshet usually takes place in October or November, and the river is again navigable for a few weeks. During the rest of the year, boats of inconsiderable burthen meet with numerous obstructions in their progress from the lowness of the water, and in many places no channel can be found of sufficient depth to admit their passage. At the distance of about seventeen miles from its mouth is the first serious obstruction to its navigation, consisting of a limestone bar extending across the river, denominated the Big Chain. Three miles above is another of a similar description. The range of rocks, of which these appear to be a portion, seems to extend across the point of land situated between the Ohio and Mississippi, presenting itself again on the latter, at the Big and Little Chains before mentioned. The falls of the Ohio at Louisville are impassable for boats of burthen, except in the higher stages of the water. Le Turt's Falls, and {261} numerous other rapids, denominated ripples, are also impassable for boats of heavy burthen when the river is at its lowest stages. In this state the river is fordable in numberless places.