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CHAPTER V.

Sandbars-plans for improving them-by wing dams--by slackwater-by dredging machines.

The bars in the Ohio may be classed-first, into those formed of hard and apparently permanent gravel; 2nd, shifting or loose gravel; and 3d, shifting sandbars. These bars have been minutely surveyed, on several occasions, by officers of the United States, whose reports furnish all the information which may be desirable in regard to them, and preclude the necessity of any detailed description. It may be remarked, however, that while they present serious obstacles to navigation in low water, they seem also to serve a valuable purpose in another respect. The Ohio, through its whole course, has in general a gentle and equable current. In low water, the river is resolved into a series of ripples or dams, with extensive basins of slackwater between them, varying in depth from two to five fathoms. It would seem as if nature had formed these bars or dams, for the purpose of collecting the water above them, and thus forming a succession of navigable pools. Following this indication, it would seem desirable, not to remove them, which is perhaps impracticable, but to pass them by some form of artificial channel, which would not greatly change the depth of the water above. Experiments, having this object in view, have already been made under the patronage of the government, by

constructing wing dams from each side of the river, so as to confine the current within narrow banks, and to give it a sufficient volume of water to wash a current for itself. A work of this character was constructed about eighteen years ago, by Col. Long, of the topographical engineers, at Henderson bar, two hundred miles below Louisville; and similar dams have since been constructed, at French island, Three Mile island, Scuffletown bar, and the Three Sisters. These were among the shoalest and most difficult places in the Ohio, and some of them have been greatly improved.

We have, heretofore, entertained sanguine hopes of the success of this mode of improvement; but our expectations, as to its efficiency, have been greatly modified by the experiments that have been made. In some instances the bars have been improved; in a majority of cases the navigation has not gained any advantage, and in a few it has been injured. This disparity of result was, perhaps, unavoidable, in an experiment so novel, and where it was attempted to control nature, in one of the most gigantic of her operations. It is not reasonable to expect that success should attend the first steps of such a movement. This mode of improvement will probably be found successful to some extent, when prosecuted upon a scale consistent with the liberality of a great nation, and reduced to sys. tem by a careful attention to the results of experiment and observation. We are sorry to say, that we believe it to be not of universal application, and that it cannot be depended upon as a form of improvement independent of other aids.

As a general rule, we are inclined to believe, that but little can be done, or ought to be done, to change the condition of the bars; and that their entire removal, if it

could be effected, would be objectionable, if not ruinous. Forming our river, as they do, into a series of pools, which afford a natural slackwater navigation, their agency could not be dispensed with, without destroying this admirable arrangement of nature. In most instances, where dams have been constructed for the purpose of changing the current of the river, or opening new channels for the water, they will be found to have failed of their purpose. Their proper office is simply auxiliary to the agencies which are already and naturally in operation, and they should be employed only to deepen and render permanent the existing channels. Thus, where the river breaks over a bar by several channels, it might be right to obstruct all of them but one, selecting for that purpose the most direct, or that which conformed itself most nearly to the general current of the river; and in cases where the river spreads out to a width greater than ordinary, the channel might be advantageously narrowed.

In regard to most of the bars, we incline to believe that but little else can be done than to open the present channels, by removing the logs, stones, or other accidental obstructions, so as to give to boats the advantage of the whole depth of water which the soundings would indicate. This is in itself an important work, and a systematic attention to it on the part of the government would be very beneficial.

It may also be suggested, that many of these bars, supposed to be the most difficult to affect by permanent artificial improvement, are composed of shifting sand, through which channels are easily cut, which would remain open during the season of low water, but would be filled up with the same species of loose sand, during the floods of the winter. It may be worthy of experiment, whether at

such places channels might not be opened annually, and kept open during the season, at an expense, trifling when compared with the value of the service. Small vessels, propelled by steam, and supplied with machinery for scooping out the sand, would open channels sufficiently deep for the smaller class of steamboats, with great facility, and they might run from bar to bar, throughout the season of low water, without incurring any formidable expenditure.

We have no doubt that this plan will be ultimately adopted, and that the business of the river will be conformed to it.

Much of the inconvenience of low water has already been overcome by the ingenuity of our mechanics, and the enterprise of our merchants, in the construction of steamboats of light draught, that ply industriously through nearly all the season of low water. But individual exertion cannot do every thing. We have put our own shoulders to the wheel with manful resolution, and we hope the government will perform its part with equal alacrity.

Among the projects for improving the navigation of the Ohio, that of converting the stream into slackwater by the construction of locks and dams has lately been spoken of, and has many advocates. It is plausibly argued that the plan, which has proved successful on the Monongahela and Kentucky rivers, must be equally applicable to any stream of similar character, and that the superior magnitude of the Ohio does not materially affect the question, as the principle would be the same. We dissent wholly from this proposition; and are glad to be able to say, that our opinion is confirmed by that of Col. Long, one of the oldest and ablest engineers in the service of the United States, to whom we are indebted for some of the following

suggestions, and whose familiar acquaintance with this river, adds greatly to the weight of his authority.

Slackwater, or lock and dam navigation in the Ohio, would be objectionable on the following accounts:

1. We have already pointed out the admirable economy of nature by which the waters of this beautiful river are arranged into a series of pools, having a gentle current, and an abundance of depth. Having but few snags or other obstructions, and impeded only by the bars in very low water, the Ohio is one of the best navigable streams in the world, for eight or nine months in every year. The obstruction from low water does not occupy more than three months in the year, nor is the navigation wholly suspended during all that period, being for the most part supplied, as we have stated, by boats of light draught. We object, then, to any project, and especially to one of which the success is problematical, which, for the purpose of improving the navigation during three months, might injure it through the remaining larger portion of the season It is obvious that the natural navigation, so long as it can be used with ordinary facility and safety, is better than any artificial navigation whatever.

2. The pools between the dams must sooner or later be filled with deposits of sand and mud, from the turbid water always brought down in times of freshet.

The quantity of mud contained in the water of the Ohio, when swelled by freshets, according to the experiments of Capt. Crane, is nearly two per cent. of the fluid volume of the river; and consists "not only of soft matter, but small stones, known to come even from the tributaries of the upper Ohio, attached to floating ice, roots of trees, &c." This matter is found as far down as the rapids at Louisville, over which they are carried by the

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