0.

To Gen. CHARLES GRATIOT,

Chief Engineer.

MEMPHIS, August 31, 1835.

SIR: The Cumberland river, at the time of the inspection in October last, was at extreme low water, affording a most favorable opportunity of ascertaining the exact position, extent, &c. of the bars and reefs of rock, which obstruct or impair the navigation: sketches of such as were deemed of most moment have since been forwarded to the Department. At that time, the superintendent was engaged in constructing the wing-dam connecting the head of Line island with the right hand shore of the river. This is the principal work, and measures five hundred and thirteen yards in length: one hundred and fifty yards of this dam will, when finished, be eighteen feet high; the balance will average six feet in height. The dam across what is called the keel boat channel at Line island, when completed, will be four hundred and sixty-five yards in length; of this, three hundred and fifty are already raised three feet above low water mark. All operations were discontinued on the river, November 29th, on account of the cold weather and high water.

The works were recommenced in April with all the laborers that could be collected. This force was first employed in raising the dam at the head and foot of Harpeth island, and in prolonging that at the foot of the island to six hundred and fifty yards in length. A breach of about sixty yards was made in the dam, at the head of Harpeth island, by water during the spring flood, which was repaired, and the dam strengthened throughout its whole extent. The work at this island is now regarded as complete, and answers entirely the object of its construction. On the 6th of August, the forces were removed to Davis's ripple: more time was consumed at Harpeth island than it would seem to have required; this was caused by the dispersion of the laborers, in consequence of the appearance of the cholera amongst them in June, when no inducement would tempt them to remain onger on the work. The operations, commenced on the 7th at Davis's ripde, were suspended before the end of the month, in consequence of sickness amongst the officers and men, there being only twelve persons for duty at the time they were abandoned A small force was employed early in Angust, in quarrying stone for the dam at Line island: this force was hereased towards the end of the month, by the remnant of the laborers trought from Davis's ripple by the superintendent. The important work at this point will, probably, be completed this fall; after which, if the season is not too far advanced, the dam at Dover shoals will be commenced. The necessity of having accurate surveys of each shoal is strongly felt. Without the information which can only be acquired from actual surveys, there must unavoidably be great uncertainty in the results intended to be produced by the wing-dams. The object for which they are constructed to produce an uniform depth of water over the bars on which they are alt; for this purpose, it is not sufficient to raise dams at the different oals to an uniform height above low water mark. As this river retres few tributary streams which materially augment its volume, the antity of water discharged through every section of it, in a given time, may be considered uniform, and consequently varies with the product of

the breadth, depth, and velocity: assuming as the depth that which is desired to produce on the shoals, and having ascertained the velocity by experiment, the required breadth of the openings to be left between the wing-dams will thereby be known. To construct dams to produce this result with the least expenditure of labor and materials, it is essential to know the distances to different points of the adjacent shore; the depth of water; the direction, breadth of the shoals, and the depth of water on them. The want of this kind of information must cause uncertainty in estimates, and lead to unnecessary expenditures. It was my intention to time my present visit to the Cumberland, so as to reach it at high water, for the purpose of determining the influence of the wing-dams at this stage of the stream, as well as to ascertain to what extent the navigation had been benefited from clearing the banks of projecting timber. The season was, however, too far advanced before I reached the Cumberland, which I found at only five feet above the point of the lowest water. It is at this stage of the river that the most decided advantages are to be expected from the wing-dams; when higher, their aid is not required; and, when lower, they are incapable of adding sufficiently to the depth, to render the stream navigable for any crafts but smaller sized steamboats and keel boats.

Clearing the banks of projecting timber has proved of essential service to the navigation, by enabling boats to approach the points; thus shortening the distances, and in many instances, especially in the convex sides of the stream, giving greater depth of water, which, in such situations, is usually near the shore. I had the honor to inform the Department in my last report, that this part of the work was nearly completed. There still, however, remains something to be done before this branch of the improvement can be considered perfect. This was pointed out to the superintendent, who immediately caused the machine boat, with an adequate company, to proceed upon this duty, under the command of an individual perfectly acquainted with the river, with instructions to commence at Nashville island, and, in descending, to remove all snags, sunken logs, projecting trees, or fallen timber, and all detached rocks which might interfere with, or interrupt, the future navigation.

My last report contained a list of such places as were capable of being improved. I beg leave here to call the attention of the Department to those works which, according to the plan of improvement suggested in the original project, come next in order. These are, a dam at Sycamore creek; one below the mouth of Harpeth river; one at Palmyra island, and at Dover shoals; one at Shelly's island; and one at Ingraham's shoals. Further blasting of the point of rocks at the Devil's chute is necessary; and a similar work at Camp Rowdy will be attended with equally beneficial results. These works are indispensable to develope fully the advantages of the improvement effected at Flax patch, Harpeth shoals, Davis's ripple, Line island, and the Devil's chute, as there is now more water at these places than at those before mentioned. There remains at this time, unexpended of the former appropriation, about $11,000. Five thousand dollars will be expended during the fourth quarter of 1835, on the works now progressing; there will then remain $6,000 available for the ensuing year, and applicable to the projected work. This sum is wholly inadequate for their construction; a further estimate will be made by the superintendent for $30,000, to be applied to that object. I have not the data necessary for estimating minutely the probable cost of the contemplated works; but, from

the extent of the improvements of which the Cumberland is capable, there will be ample room for applying the surplus advantageously, should the amount called for by the superintendent exceed that which shall be found necessary for completing the dams.

As these works form a prominent part of the system commenced for the improvement of the Cumberland, and as but little advantage can be deved from what is already done, unless the system be carried through, the Lecessity of the appropriation is obvious.

I have the honor to be, sir,

Very respetfully, your obedient servant,

A. H. BOWMAN, Lt. of Engineers.

P.

CUMBERLAND ROAD OFFICE,

Columbus, Ohio, October 12, 1835.

Brig. Gen. C. GRATIOT, Chief Eng. Washington.

SIR: I have the honor to present my annual report of the condition of that portion of the Cumberland road, in Ohio under the control of the United States, exhibiting the progress made in its construction since the 30th of September, 1834.

SECOND DIVISION-Embraced between the town of Zanesville and the city of Columbus.

Masonry. The several structures between the 22d and 53d miles, inclusive, have been thoroughly repaired and pointed, preparatory to this part of the road being delivered up to the State.

Carpentry. The wooden superstructure of the bridge over the south fork of Licking creek, on the 25th mile, has been repaired and strengthened by additional braces to secure it against lateral motion. Some slight repairs were made to the bridge over the canal feeder, on the 32d mile, and others will be required to the flooring of those over Black Lick, Big Walnut, and Alum creeks, previous to their being turned over to the State.

On

Covering. The third and last stratum of metal was placed upon eleven miles of the road, viz: Between the 22d and 32d miles inclusive, during the winter and the early part of the spring of this year; and this portion of the road was received by the Governor of the State in the month of May. From the 32d mile to this place, a distance of twenty-one miles, nearly the whole of the metallic covering has been prepared for the three strata. the 30th of September, seventeen miles of this portion were covered with six inches of prepared gravel and quarry limestone, leaving but four miles without any metallic cover. The whole of this division of the road would have been completed, so far as regards the two first strata of metal, early in the last month, had not the unusually wet weather experienced this year, retarded this branch of our operations from the very commencement of the working season. Much greater difficulties have been encountered than was at first anticipated, in procuring a sufficient quantity of gravel for the covering. having nearly exhausted the whole district of country between the Licking canal feeder and this city, of that material, in obtaining the required amount of stone for the completion of this section. Such progress, however, has been made in the work, as to warrant the belief that this division will be finished, and placed under the control of the State, in the course of the next month.