of which was prostrated by a violent southeast storm, leaving for the aggregate length of the line standing on the 30th of June about 3,200 feet.

From the soundings made on the lines of the triangulations, and especially from those made upon lines crossing the main navigable channels, it does not appear that any considerable changes have been produced in the pass by the operations of the contractors prior to the date last mentioned.

For particulars in reference to the topics just considered, see Appendix, Doc. No. 11, and Doc. No. 12 and Doc. 13, being copies of my reports of the monthly progress of the work.

In fairness to the contractors, and in so far as relates to the enlargement of the channel at the Southwest Pass, it is proper to withhold any decisions as to the final efficiency of their operations till the expiration of the period of their contract, which will terminate on the 15th of September next.

But in relation to the improvement of Pass à l'Outre, the fact that nothing appears, as yet, to have been done thereat towards its improvement, seems to authorize the inference that the contract for this improvement must unavoidably be abandoned by the contractors, the unexhausted period of their contract being only half a month.

The subject next claiming attention is the further prosecution of works of improvement on the western rivers. My views in reference to this subject have been fully presented in my unpublished report of September 1, 1856, under the head of "Estimate of funds required for the prosecution of western river improvements during the fiscal year beginning July 1, 1857, and ending June 30, 1858." The same views, with a few modifications relating to the improvement of Red river, and with the omission of any provision for the improvement of the Des Moines rapids and other local works, are deemed equally applicable and appropriate to the said improvements under existing exigencies, and are referred to accordingly as a component part of this report.

The item requiring modifications, as above, is amended as follows, viz:

In addition to the craft now for service in Red river, a steam dredge boat, with mud scows, yawls, &c, should be procured at a probable cost of $10,000. The cost of working the dredge boat, &c., for nine months may be estimated at $850 per month, or $7,650 per year.

Hence the corrections in question being applied to the statements in reference to Red river, as contained in the cited estimate, will give the following summary results, viz: Cost of craft for the improvement of Red river, including a dredge boat, scows, &c., $28,000; annual cost of working and preserving said craft, the dredge boat, scows, &c., included, $52,350.

The same corrections being introduced into the tabulation, near the end of the estimate referred to, will give the following as the corrected tabulation for this report:

Table of appropriations for a series of five years.

With respect to the adoption of a system of annual appropriations for the prosecution of western river improvements, I conceive there can be no doubt of its propriety and economy. On at least three dif ferent occasions liberal appropriations have been made by Congress for this service, covering the cost of the various kinds of craft, &c., required for the service, and the working of the same for a period limited by the balances remaining for the prosecution of the work after deducting the cost of the craft. In each of the instances alluded to the balance in question was sufficient merely to keep the craft employed in the public service during a period of two or three years only; after the expiration of which the craft, together with its equipments, &c., has been sacrificed at public sale for less than one-sixth of their prime cost. In this way nearly one-half of the prime cost of the boats, &c., procured under each appropriation for western river improvements has been virtually wasted. It is believed that the sacrifices thus incurred may be avoided by adopting the system of appropriations herein suggested, and exemplified in the table.

It will be perceived that no provision has been made in the table for any works of a local character, or for the removal of obstructions from the mouths of the Mississippi. The improvements of the rapids of the Mississippi and Dubuque harbor have been transferred to Captain Palmer, while the late appropriation for the improvement at the mouths of the Mississippi has been encroached upon to the extent of $2,500 only, and needs no addition for the current fiscal year.

COMMERCIAL STATISTICS AND STEAMBOAT DISASTERS.

The compilation and arrangement of the various details of information proper to be embraced under these heads has been confided to Doctor M. P. Breckinridge, who has been employed for some time past as recorder and accountant in my office, and who has been requested to visit Cincinnati, St. Louis, and other commercial points, in quest of the desired information. His report on these topics is hereto appended. (See Appendix, Doc. No. 14.) A full and clear exhibit of

all the items of intelligence appertaining to western commerce would be attended with great labor, trouble and expense, far greater than I have had it my power to bestow, either personally or by proxy.

In the document referred to a brief abstract merely has been attempted, with the view of exhibiting the more prominent features of the subject. The sources whence the information has been derived are duly recognized and acknowledged in the document.

With respect to the utility and importance of the several lines of communication-viz: of rivers, canals and railroads-in a military point of view, and the facilities, despatch and cost with which troops and military supplies of all kinds can be conveyed from point to point, or from one commercial depot to another, they may be readily inferred from the tables contained in the document referred to, in which the distances between important points are exhibited in miles, the duration of the transit for freights and for passengers over these distances, and the ordinary cost of conveyance for freights and passengers through the same distances are exhibited.

Respectfully submitted,

S. H. LONG, Lieut. Col. Top. Eng., Late Superintendent Western River Improvements. Colonel J. J. ABERT, Chief Topographical Engineers, Washington, D. C.

P. S.-Letters from Captain Johnson, dated on the 31st ultimo, inform me that no favorable changes in the width and depth of the channel at and near the mouth of the Southwest Pass, produced by the operations of Messrs. Craig and Rightor, were perceptible at that date. Also that the smallpox had broken out among their laborers, and that they had been compelled to repair with their pile boat, &c., to New Orleans in quest of medical aid.

S. H. LONG, United States Army.

APPENDIX.

DOCUMENT No. 1.

Contract-Charles Gregoire, president, with S. H. Long.

This agreement, made between the president of the Dubuque Harbor Company of the first part, and the government of the United States of the second part, witnesseth: That the said party of the first part agrees to construct a causeway leading in a direction south 651° east from the foot of First street, in the city of Dubuque, to the point "A," on the river side of the outer island, immediately below the main outlet of Dubuque harbor, said causeway to be surmounted by a roadway 30 feet wide, to be elevated at least 3 feet above extreme high water of the river, to be furnished with a slope of 1 in 6 on its upper side, the whole to be completed in one year from the date hereof, unless prevented by the prevalence of high water in the river.

And it is further agreed that so much of the material for the causeway shall be taken from the bottom and sides of the channel leading from the main river, through waples cut to the slough or basin, whenever said channel is touched by the causeway, as will leave the channel 200 feet wide, or of a width and depth not less than what exists at present. The position and direction of the causeway to be determined by an officer or agent of the United States, and the work carried on to completion in accordance with such determination and plans as approved by him.

In consideration of the work done on said causeway, and after the same shall have been completed, the United States agree to pay to the said party of the first part the balance of appropriation remaining on hand, after all just liabilities incurred by the United States are paid. Said balance to be paid by the United States, through their agent, after the agent, from inspection, shall have ascertained that all the provisions of this agreement, as regards the construction of the causeway, shall have been fulfilled by said party of the first part.

And it is further agreed that any expense incurred by the party of the first part in the construction of the causeway over and above the balance of appropriation paid to them shall not constitute any grounds for a claim against the United States, or against any further appropriation which may be made by Congress for the further improvement of the harbor of Dubuque. And said causeway shall remain a free and open highway.

Done in triplicate, this 6th of September, 1856.

CHARLES GREGOIRE,

President Dubuque Ilarbor Company.
S. H. LONG, U. S. A.,

Superintendent Western River Improvements.

DOCUMENT No. 2.

Colonel Long to Hon. G. W. Jones.

LOUISVILLE, December 22, 1856.

DEAR SIR: Having been apprised that sundry respectable citizens of Dubuque are desirous of some expression of my views in reference to the capabilities and importance of Dubuque harbor, I take leave briefly to offer, through you, some of my convictions on these interesting topics. The site of the harbor is on the westerly side of the Upper Mississippi, in latitude about 421° north, and is effectually landlocked and separated from the main river by a cluster of islands, which shield it from the encroachments of floating ice and other drift in all stages of the river, except in extraordinary floods, when the overflow covers the islands to the depth of a few feet only. During the periods of such overflow the influx of drift of all sorts may readily be prevented by the construction of levees of moderate height along the exterior margin of the outer island.

The present harbor or basin embraces an area of between two and three acres, in which there is a low water depth of about four feet, and is sufficiently capacious to accommodate some eight or ten steamers of ordinary dimensions, but is rendered inaccessible to such craft during the low stages of the river for want of a navigable channel connecting the harbor with the river.

By removing that portion of Bass island situated between Barney's cut and the line of the causeway in progress of construction by the Dubuque Harbor Company, and by dredging the inner and outer sloughs, including the site of Bass island and the main outlet of the harbor, to the depth of four feet below the surface of extreme low water, the harbor may readily be enlarged to an area of more than twenty acres, and to a capacity sufficient to accommodate more than one hundred steamers with safe protection during the period of the winter frosts.

The materials excavated by removing Bass island, dredging, &c., may be employed to great advantage in the formation of levees, terraces, causeways, &c., of earth work upon the islands, across the sloughs, and around the harbor, by means of which not only will the capacity of the harbor be enlarged, but the facilities for business transactions connected with it will be incalculably multiplied.

The number of steamers now plying on the Mississippi above Rock island, during the season of navigation, may be computed at about twenty, and will, in all likelihood, be increased to at least one hundred in the course of eight or ten years, most of which may readily and conveniently find and occupy a safe and commodious harbor at Dubuque.

The importance of this point is greatly enhanced from the fact that it has been made the terminus of the Great Central Railroad of Illinois on the Upper Mississippi; also from the consideration that other railroads, leading southward, westward, and northwestward, which are not merely in project, but some of them actually commenced, diverge from the same point, and lead through a region of incalculable wealth in an agricultural and mineral point of view.

The population of Dubuque amounts at this time to about eight thousand inhabitants, and is rapidly increasing at the rate, probably, of more than twenty per cent. yearly, so that in less than five years it will amount to more than double that number.

To the best of my knowledge and belief, there is no other position. on the Upper Mississippi that presents equal facilities for the construction of a capacious, safe, convenient, and commodious harbor in any of these respects comparable to those afforded at Dubuque.

S. H. LONG.