The :Mississippi, including the lissouri, (which ar ticles see) the Ohio, and all its other branches, may generally be stated as affording a navigation through a triangle of country, of which the line from New Orleans to above Pittsburg on the Ohio, 1000 miles, niay be reckoned the base, and the other sides 1600 miles each ; so that the basin of navigation is nearly one half greater than that of the Volga. The comparative slopes of tbese basins are also similar: the fall from the Vishnie Voloshok, to the lake Ladoga, is, (according to Captain Perry) 56S feet ; the height of Lake Erie, above the tide-water in the Hudson is known, by the levels of the proposed Grand New York Canal, to be 565 feet, and we may rca sonably suppose the slope of the St. Lawrence through Detroit, and the Hudson between Albany and New York, to be much the same with that of the Neva from Lake Ladoga to the Baltic. Now the waters of the Lake :Mi chigan, when high, are said to back into the head waters of the Illinois, a branch of the Mississippi, ancl admit boats to pass from the one to the other ; so that these head waters are, in all probability, very nearly at the same level as those of the 'rwer branch of the Volga. From this gentle inclination, ancl the very winding course of the rivers, which are in general two or three times longer than the direct distance, the branches of the Mississippi are, for the most part, navigable for some kind of craft, almost to their heads. Vessels of 300 tons ascend as high as Natchez, more than 400 miles from the sea; but their progress, owing to the velocity of the current, is so very, slow, that the passage from the sea to New Orleans is from 5 to 30 days, whilst the descent, of the same dis tance, does not exceed 12 or 14 hours. The usual pro gress of a boat up the river is about five leagues per day. But the steam-vessels (of which there are now upwards of one hundred on the Ohio and Mississippi) sail against the stream at the ratc of sixty miles a.day, when heavily laden. The current down the Mississippi is from three to four miles an hour.* Between Arkansas and the Delta, the current is one-third less, and thence to the outlet it is diminished by one half.
The main river is navigable uninterruptedly, as high as the falls of St. Anthony,through fifteen degrees of latitude, and measuring by the stream about 2000 miles. The chief branch is the Missouri, which joins St. Louis, 15 miles above by water, and adds a navigation of about 2500 miles along the main stream. Its chief branches are, the Osage, Grand River Kanses, Platte, Yellow Stone rivers, cach of which may be said to add from 500 to 1000 miles of navigation, and there are many smaller. The other chief branches of the ;Mississippi, above the Missouri, are the Illinois, River Des Moines, Rock river, and St. Peter's, to each of which we may allow 4 to 500 miles of navigation; and from some of which there are only short portages to the lakes of Upper Canada.
But by far the most important branch is the Ohio, as affording a direct communication with the eastern states, and being already the channel of a great inland trade. The Alonongahela and the Allegany rivers unite near l'ittsburg, and form a great river, the Ohio, which flows 918 miles to join the Mississippi in 37° ; beside others ef lesser note, the Ohio receives from the N. W. or ight side, in descending from the junction of the Alle gany and Ionongahela, Big Beaver, Muskingum, Hock hocking, Scioto, Little .Miami, Great Miami, and Wa bash ; from the south-east or left side, conies in the Little Kenhawa, G reat Kenhawa, Big Sandy, Licking, Kentucky, Salt Greene, Cumberland, and Tennessee. The Alle
gany branch, which rises in the state of Pennsylvania, is navigable a distance of 270 miles, and by French creek has a direct communication towards lake Erie. Its out let is 350 yards in width, the mean velocity is a mile and a half per hour, but when the watcrs are high it is four miles. The Monongahela is navigable, except at low water, in dry seasons, to Morgantown, for boats 100 miles from its mouth ; and during the swell of the waters in spring and autumn, ships of 400 tons may enter, and proceed some distance from its mouth, which is 440 yards in width ; the mean velocity of the current is two nailes per hour, excepting during the period of the swell of the water in Spring and Autumn, when it is froni three to four.
The Illlaskingurn, or Elk's Eye, of which the outlet is 25 yards in width, is navigable for small boats, through its whole course, to its head in a small lake, a tlistance of 150 miles; and large boats ascend to the Three Legs, 110 miles from its mouth. Great Hockhocking, which unites with it 215 miles from Pittsburg, is navirble to the distance of 70 miles, from its source to the Cayhav River, which communicates witta lake Erie ; there is hut a mile of portage. The great Kanhawa rises in North Carolina, in the easternmost ridge of the Allegany mountains, and joins the Ohio 283 miles below Pittsburg. Tne navigation is good for the distance of ten miles ; thence to the Falls, 60 miles, the stream is rapid, and the passage of boats is interrupted by a cataract called the Great Falls, 70 miles distant from its mouth, which is 500 yards in width. From the Great Kanhawa to James' River, which falls into the Chesapeake bay, the portage is but a few miles. Great Sandy river is navigable to Cumberland Mountain. "rhe Big Scioto, which falls in under the parallel of 38° 43', at the distance of 330 miles from Pittsburg, is navigable nearly 200 miles, to a point from which the portage is but four miles to Sandusky river of Lake Erie. Salt river, which discharges itself on the south-east side 20 miles from the rapids, by an outlet 150 yards in width, is navigable thence to the dis tance of 60 miles. The Great Miami, or Rocky river, which enters 435 miles from Pittsburg, is, at the distance of 120 miles, navigable for loaded canoes. Licking river, which enters 422 miles from Pittsburg, is naviga ble to the distance of 70 miles frorn its mouth. Kentucky river, which enters 496 miles from Pittsburg, is navigable in high water for loaded boats to the distance of 160 miles from its mouth. Cumberland enters the Ohio 883, and Tennessee 896, below Pittsburg; both those great branches are navigable many hundred miles above their mouths. BulTalo river is navigable for boats of seven tons for 150 miles. The Wabash, which joins the Ohio 310 miles below Fort Pitt, lat. 37° 41', is navigable for small boats drawing three feet water to Ouitanon, a distance of 412 miles. The Cumberland, 948, is navigable, for ships of 3 or 400 tons, two bundled miles above Nashville. The Tennessee, the largest branch of the Ohio, rises in the Iron Mountains, on the borders of Carolina and Georgia, and passes across the Cumberland Ridge, where its bed is confined within the breadth of 70 yards, though above the mountains it is 800 yards, and at its mouth 500 yards. Vessels of burden can ascend no higher than the Mussel shoals, which extend 20 miles in length, and (except in high floods) interrupt the na vigation. From these shoals it is navigable for vessels of 40 tons to the mouth of the Holstein, and up that river to Long Island, 600 miles from the mouth of the Tennessee.