The method proposed as a remedy for this obstruction consists of forming a high-water channel along the left bank of the river, and in rear of several huge masses of rock standing nearly midway of the river-bed, between which and the left bank there is a channel already partially formed, but still obstructed by numerous rocks of far less size than those just mentioned.

It is proposed to remove or reduce the rocks in this channel, in a manner to clear it of obstructions, to a depth or level 2 feet above low-water mark, and to a width of 50 feet. The amount of excavation required for this purpose is estimated at 1,000 cubic yards, and its cost at 623 cents per cubic yard.

On the supposition that a channel 6 feet above low water should be deemed adaquate to the purpose, one-tenth only of that amount of excavation, or 100 cubic yards, will be required.

No. 47. The Suck.-Sufficient has been already advanced in relation to this pass, as also to those hereafter to be noticed, to give an adequate idea of their characters and the value of their structures. It only remains to exhibit the manner and probable cost of their contemplated improvements.

Two methods of improving the Suck have been brought to our partieular attention, viz: the first, which contemplates the forming of a lowwater channel 50 feet wide, by excavating across the rocky points on the right side of the river through the distance of 1,020 feet; and the second, which consists of the removal of obstructions and the partienlar formation of a new channel through a distance of 800 feet on the left side and near the left shore of the river; the former providing for a channel removed to the distance of 80 to 100 yards from the present low-water channel, and the latter either in its immediate vicinity or but a very few yards from it.

The amount of excavation required agreeably to the first method will be more than 12,000 cubic yards, at 75 cents per yard. That required by the second method, little more than 8,000 cubic yards, at 873 cents per cubic yard.

The first may be preferable on account of the greater distance through which the fall of the river at this place will be distributed by its adop tion; while the latter promises the advantage of being appropriate for a boating-channel at all stages of the water, while at the same time its extent is deemed sufficiently great to moderate the velocity of the current to a speed that may be resisted by the force of warps.

Moreover, the head of the proposed channel on the right shore will be situated immediately at the debouchure of Suck Creek, which, during the prevalence of a heavy rain or shower, assumes the character of a torrent, and brings down with its waters large quantities of gravel and pebbles, and even rocks of large size, which would be liable effectually to block up a channel on that side of the river. The direction of this creek, near its mouth, may be so changed as to obviate the difficulty above suggested, but this object can be accomplished only by the formation of a strong dam a little above its mouth, the cost of which would be very considerable, while its being necessarily located in a gorge, through which a part of the water of the river pours with great violence in a very high stage, would be likely to endanger high-water navigation on that side, unless the same were raised quite above the reach of the highest freshets.

From these and a variety of other considerations, which need not be urged on this occasion, we are induced to prefer the second method, in

connection with which far greater facilities for warping are presented than are to be had in connection with the other method.

No. 48. The Boiling Pot.-The improvement contemplated at this place, in addition to those already made, which are to be regarded as valuable in so far as they have contributed to enlarge the passage through which the river has to pass, consists in the formation of a new channel 50 feet wide across the left point or on the left side of the river, opened to a depth or level 18 inches below low-water mark; also in the reduction of a large rock attached to the left shore, about 200 feet above the point, and several other rocks situated between the large rock and the point, together with others below the point.

The amount of rock contemplated to be removed or reduced is estimated in the aggregate at 1,773 cubic yards, about one-third of which is under the surface of low water, and the average cost of its removal at 873 cents per cubic yard.

The object of removing the large rock above the point is, that boats may be able to ascend, by the aid of warps, past the point where it now stands during the high stages of the water, and arrive at a point above it, whence they may pursue their voyage upward by the agency of steam without being in danger of being drawn back through the pass. By these means facilities for warping, in all stages, will be afforded on the left side of the river.

No. 49. The Skillet.-The only improvement required at this place consists in the requisite fixtures for warping, which is required only during the lower stages of the river, and may be applied in either of the ways already suggested, according to the discretion of the superintending engineer.

No. 50. The Pan.-Both sides of the river at this place were carefully examined, with a view to the most favorable locality for an improvement, and resulted in establishing the conviction that an improvement having for its object the accommodation of ascending boats during all the more elevated stages of the water, should be located on the right shore.

The particular locality on this side of the river, best adapted to the purpose, is in the rear of a series of high, massive rocks, extending along the side of the present low-water channel, between which rocks and the right bank of the river is a channel like that at the point of rocks above the Suck already partially formed. By opening this channel more effectually, which must be done at the expense of blasting and reducing a large quantity of rocks, a channel for ascending boats may be formed conveniently situated in all its relations for the application of warps. The distance through which excavations are required, in order to open the channel, is 700 feet, and the depth such that the bottom of the channel may be elevated 2 feet above low-water mark, the width being 50 feet. According to these premises, the amount of excavation will be about 5,000 cubic yards, the cost of which is estimated at 623 cents per yard. In case the bottom of the channel is elevated 3 feet above low water, which may be found sufficiently low for the purpose, less than balf the amount of excavation will be required.

The drawings contained in second part of Vol. II, under the title of "Sketches of the shoals and rapids of the Holston and Tennessee Rivers, below Knoxville," are exhibited on nine sheets, which are numbered from 2 to 10, (No. 1 being a project of a wing-dam, &c.,) and will afford additional information relative to the courses of the river at the several shoals, &c., herein considered, the positions of the bars, islands, aud

channels connected with them, and the contemplated sites of the im provements that have been recommended.

The several items of expenditure contemplated under this head will be recapitulated in a more condensed form under the succeeding head.

5. THE PROBABLE EXPENSE OF IMPROVING THE NAVIGATION OF THE TENNESSEE RIVER, FROM KNOXVILLE TO THE STATE LINE, BETWEEN TENNESSEE AND ALABAMA.

The prices exhibited under the preceding head are such as are deemed fully adequate to the accomplishment of the several kinds of work to which they are respectively annexed, in that state of the river only which is the most favorable for its execution, no allowance being made for unhealthiness of the localities, interruptions by inclement weather, and unavoidable stoppages occasioned by a more or less frequent recurrence of freshets during the low-water season, viz, occasional rises of the water. On this account alone, we should think it reasonable to add at least 334 per cent. to the amount accruing in conformity to the prices already stated, and shall accordingly increase the amount of our estimate by including such a percentage.

Moreover, it will be perceived that no allowance has been made on the score of engineering, superintendence, and ordinary contingencies, which we shall estimate at the rate of 15 per cent. on the amount required on account of labor and workmanship.

With a view to such an arrangement of the different kinds of work which will be calculated to facilitate its distribution by contracts, we have included that part of it which relates to the removal of obstructions of all kinds in one table, and that which relates to the construction of dams in a separate table, under a belief that each description of work thus distinguished may with propriety be comprehended under separate sets of contracts.

Accordingly, the following synopsis is intended to exhibit the several items proper to be included in contracts for the removal of obstructions to the navigation of the Holston and Tennessee Rivers.

Table No. 2, agreeably to the views before suggested, exhibits the dimensions and other circumstances relating to the wing-dams deemed necessary to the improvement of the navigation of the Holston and Tennessee Rivers, between Knoxville and the Alabama State line. Hence the estimated cost of deepening the channel, so far as this operation depends on the removal of rocks, logs, trees, &c., the several items of which are exhibited in table 1, amounts to

And the estimated cost of improvements, so far as they depend on construction of dams, amounts to......

$23, 190 02

These amounts give for the aggregate cost of the labor and workmanship deemed necessary to the accomplishment of the improvement, independently of any allowance for interruptions, superintendence, &c., or contingencies

14,740 00

37,930 02

To this amount should be added on account of unavoidable interruptions by freshets, &c., 334 per cent. on the above, amounting to.....

12,645 00

Amounting to.................

50,575 02

To this amount, moreover, should be added on account of engineering, superintendence, contingencies, &c., 15 per cent. on the amount last stated.. 7,586 25 Which gives for the aggregate cost of improving the navigation of the Holston and Tennessee Rivers between Knoxville and the Alabama State line in the manner herein proposed

58,161 27

The distribution of the work, as contemplated in connection with the following tables, has been made with special reference to the regulations prescribed by the legislature in their provisions for carrying it into effect. In relation to this subject, however, we take leave to remark that the nature and extent of the operations at the several points herein designated are too variable and indefinite to be comprehended under specific contracts; it is accordingly believed that the work may be executed to better advantage, as well in respect to its efficiency as to its economical accomplishment, by procuring the requisite utensils, boats, &c., and employing experienced superintendents and industrious laborers for its execution.

Returns, based upon vouchers for the purchase of utensils, provisions, &c., and upon the pay-rolls of the superintendents and laborers that may have been employed, may be statedly rendered to the board of internal improvements, together with any other vouchers relating to the cost of the work, by which means an accurate exhibit of expenditures may be furnished whenever called for.

This mode of carrying on the work would be more specific with regard to the objects of expenditure than any other that could be adopted; and at the same time, while it would be exempt from the risk incident to contracts for the performance of work not susceptible of an accurate definition or measurement, would protect those engaged in it from losses, and the means applicable to its accomplishment from being expended upon exorbitant contracts.

All which is respectfully submitted.

Topographical Engineers, Brevet Lieutenant-Colonel.
S. H. LONG,

Col. S. D. JACOBS,

President Board of Internal Improvement for East Tennessee.

TABLE I.-Exhibiting the localities and nature of the several obstructions to low-water navigation in the Holston and Tennessee Rivers, and the probable cost of removing them.

[NOTE.-Items marked thus (*) are not included in the sums total.]