to Louisville, four inches per mile. Below Guyandot, the character of the river becomes materially changed; it here enlarges its bed, and flows onward with a diminished current; the level reaches are longer, and the descent at the ripples less. This enlargement of its bed, however, renders the depth over some of the shoals in this part at the river, very slight at low water, forming several very shoal sand and gravel bars. From Cincinnati to Louisville, the navigation becomes comparatively much improved. There are two or three bars on this section, and some dangerous snags below the mouth of Kentucky river, which require attention. It would be desirable to give a specific description and sketch of each shoal, were it not that their great number and similarity would render such description a monotonous repetition of nearly the same circumstances.

"An important feature in the Ohio river is observable in the fact, that at all the islands are also located the worst shoals and rapids, or falls. These islands are considered rather the effect, than the cause of this fall, and formed, like the alluvial bottoms, by the gradual deposite from the river, which, at those points being spread out at low water, leaves some portions of the projecting parts of its bed uncovered. In respect to Captina and Buffington's islands, the low water channel at each deflects from the main direction of the bed, and passes off laterally, through a narrow and circuitous route, around the island. The main or direct channel, in both the cases alluded to, is rendered dangerous by rocks, and too shoal at low water for navigation.

"The rocks in the Ohio chute, at Captina island, appear, from recent examinations, to be of a detached character, and susceptible of removal. The direct channel at Buffington's island, is bounded by a ledge of stratified sand stone rock, projecting into the river, which is supposed to continue entirely across the channel, beneath the gravel

bottom; it is, however, situated nearly at the foot of the rapids. Some loose rocks are scattered in this channel.

"With regard to the islands, and particularly those at which the low water channel deviates from the direct continuation of the main bed of the river, shifting bars are always found under the lee of the islands. This rule appears, from the result of my examination, to be of general application in regard to all similar points on the river. The water, at high stages, passes with the greatest volume and current through the most direct and spacious channel, which then predominating, throws into the foot or junction of the smaller passage powerful eddies, depositing therein a bar, which again changes and deepens upon the fall of the waters. With regard to the rapids, called Letart's falls, the river here passes over a rocky bottom, with a descent and current far greater than is found at any other point above the falls; the bottom is free from dangerous projections, and the concentration of the water at this place, by the more prominent parts of the rocky bed on each side, renders the depth over these rapids much greater than upon most of the shoals in the river. The current, which is here five and three quarters miles per hour, at a moderate stage, can, in general, be stemmed by steamboats of sufficient power; but for keel boats, and the lighter class of steamers, permanent warping fixtures are here necessary. The points most requiring immediate attention, in the shoaler section of the river, lying between Pittsburgh and the junction of the Muskingum, at Marietta, are, Logtown bar, Black's and Brown's islands, Beech Bottom bar, McMahon's creek below Wheeling, which requires the removal of many dangerous rocks and logs, Captina island, Petticoat ripple in the long reach, Carpenter's bar, and Marietta island; at this latter point, the junction of the Ohio channel, opposite to the town of Marietta, is crossed by a large bar of loose shifting sand, which makes from the foot of the island

across to the mouth of the Muskingum. At the head of the island, three miles above, the Virginia channel is crossed by a shoal gravel bar.

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By the execution of that part of the plan of improvement now in progress, viz: the removal or clearing the channel of all sunken logs, stumps, snags, and projecting rocks, the navigation at low stages, and particularly for light draught steamers and keel boats, will be rendered much safer, and even practicable for a deeper draught, than it is under present circumstances considered prudent to employ. There are some sand and light gravel bars, which are among the very shoalest on the river, but which, notwithstanding, are not ranked among the most serious obstructions, from the comparative safety with which their passage may be attempted. A system of improvement, having for its object to secure a specific depth of water at all seasons, sufficient to meet the demands of the trade upon those streams which are rendered impassable during the dry seasons, from the diminution of the supplies derived from their tributaries, can be effected with certainty only by a series of dams and locks.

"As this mode is not, however, contemplated with regard to the Ohio, the concentration of the river into one channel, and the appropriation of all the water passing, to that object, during low stages, will, it is believed, accomplish all the further improvement contemplated."

The project of removing the snags and sunken timber from the beds of the Ohio and Mississippi, originated with Captain Henry M. Shreve, who next to Fulton, has done more for steam boat navigation in the west, than any other man. He contrived a steam boat, for this purpose, which operates with such speed and energy, that scores of the largest trees are raised in a day, with the assistance of a few hands. The business of removing snags is performed only when the water is low; at other times the crews of the boats are employed in cutting away the

overhanging timber from the falling in banks, that is from such banks as are gradually becoming undermined by the action of the current, and which supply the greatest amount of these dangerous obstacles to navigation. The boat is of the most simple construction, yet has such power, that the largest tree, however firmly fixed, is removed in a few minutes. A number of these ingenious vessels have been employed for several years, under the direction of Captain Shreve, in the Ohio and Mississippi, and thousands of snags have been removed by them. In the year ending in September 1833, 1960 were taken up in the latter river, and supposing many to have been left, the chances of danger to ascending vessels, were diminished by at least that number. Within the same year, the crews of those boats were employed, when the water rose too high to admit of working on the bed of the river, in cutting away the trees which overhung the stream, or stood on banks liable to be undermined,, and actually felled 10,000 trees, which must soon have been precipitated into the mighty current. The same operation has now been continued for several years, at an annual expenditure of less money, than was previously lost by the yearly destruction of property, from this single cause to say nothing of the loss of life. It is true that the obstructions are continually renewed; but the number of trees which are thrown into the stream, must be annually decreased, by the settlement of the country, and the consumption of timber for fuel, by steam boats. Firewood has already become a valuable article; and but few years will elapse before every tree, on the margin of a navigable river, will have acquired a value sufficient to induce measures for converting into fuel, the whole of that immense mass, which would otherwise have been carried away by the spring floods.

The sandbars of the Ohio, present a more permanent and serious obstruction to navigation. These are numer

ous-many of them extending entirely across the bed of the river, and affording less than two feet of water in any part. To cut a channel through a bank of sand, would not be impracticable; but the excavation thus effected would be filled by the deposites of the next flood. It is difficult to project a remedy for this evil, which shall be effectual and permanent. About ten years ago, Colonel Long of the topographical engineers, was instructed by the government to make an experiment, and adopted the plan of throwing out wing-dams from each side of the river, so as to confine the current within narrow bounds, and to give it sufficient volume to wash a channel for itself. He spent a summer in constructing such a work at Henderson bar, 200 miles below Louisville, The dams were constructed of piles driven into the sand and rising but a few inches above its surface. The enterprizing Captain Shreve has since pursued and improved the same plan, and has constructed similar dams at French island, at Three-mile island, at Scuffletown bar, and at the Three sisters. These were formerly the shoalest and most difficult bars in the Ohio; they have been greatly improved, and may now be passed in the lowest water. The most extensive of these works, and that which, if successful, will most satisfactorily attest the correctness of the principle which applies to them all, is the one now in progress and nearly completed, at Cumberland island, near the mouth of Cumberland river. It is proposed to change the channel of the river, so as to force its waters to pass between the island and the Kentucky shore, by which means a channel will be washed through the bar below, and the mouth of the Cumberland river relieved of a very formidable obstruction. Two hundred men were employed year on this work. The length of the dam is about half a mile, its width at the base thirty feet, and its height sixteen feet; it is composed of large masses of limestone rock, quarried from the shores above.

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