sary to remove a portion of the dam built across the chute south of Piasa Island by my predecessor in 1875-77. Before that project could be carried into effect the funds available for its execution were by the river and harbor act of March 3, 1881, diverted to the improvement of Alton Harbor. Accordingly nothing was done at Piasa Island. The difficulty of navigating the north chute continued to increase until finally the high water of 1882 moved a large bar down over the mouth, shutting it off altogether during the succeeding low water. Steamboats were compelled to find their way through the south chute, seeking such depressions as existed in the dam for a passage over it. This became more and more dangerous as the stage of the river declined. A suspension of navigation at this point was threatened. Under these circumstances it was thought proper to depart from the programme previously laid down for the expenditure of the appropriation, and to allot to Piasa Island tunds sufficient to make a safe passage-way through the dam.

It was found upon examination that the most suitable place for the opening was at the south end of the dam near the Missouri shore. An attempt was made to undermine the dam with the hydraulic excavator belonging to the works, arranged as in a Roy Stone dredge, but owing to the great depth-20 feet-of the foundation, it was not successful. The contrivance showed its efficiency as an excavator, however, raising in some cases 1,000 cubic feet of sand per hour. An arrangement was then made with Messrs. H. S. Brown & Co., of Quincy, Ill., to remove the dam, using the ordinary dredge. A cut was made, having a width of 385 feet and a least depth of 6 feet at low water, after which there was no obstacle to navigation at this place. For details see Appendix 11. The expenditures were $2,750.11.

ALTON HARBOR.

The improvement of Alton Harbor was begun in September, 1881, under a separate appropriation for the "Improvement of the harbor and Mississippi River at Alton." My annual report of last year under that title-see Annual Report of Chief of Engineers for 1882, page 1644gives a description of the plan adopted and the history of the operations up to that time. A dike opposite and above the town, running obliquely down-stream, had been begun, and was about one-third completed.

The river and harbor act of August 2, 1882, made provision for the improvement of the Mississippi River in the following language, viz:

Six hundred thousand dollars from Cairo to the Illinois River, including Alton Harbor, on which a sum not exceeding thirty-five thousand dollars shall be expended.

Work was accordingly begun in September, 1882, under this appropriation. It consisted of extending and raising the dike begun under the special appropriation.

The dike was extended to the full length contemplated, 4,800 feet. For a distance of 3,000 feet it was raised to its full height, 14 feet above low water; for a distance of 700 feet its height is 12 feet, and for the remaining 1,100 feet its height is but 10 feet above the same plane. To complete it as originally designed, it should be raised to the uniform height of 14 feet throughout, but it is not now certain that this will be necessary. It has exerted a very favorable influence upon the landing

at Alton, and as this action is still continuing, it is quite possible that the desired result will be attained without further work.

The work upon this dike has been carried on during three distinct periods, viz, the autumn of 1881, the spring of 1882, and the autumn of 1882. The amount accomplished during the first period was small, owing to unexpected floods, which occurred during what is usually the low-water season. About 3,500 cubic yards of dike were constructed, at a cost of $2.90 per cubic yard. During the second period the river was at about the average spring stage; the amount of work accomplished was about 20,200 cubic yards of dike, at a cost of $1.10 per cubic yard. During the third period the season was favorable, and the river was at a low stage; the amount accomplished was about 35,000 cubic yards, at a cost of 97 cents per cubic yard. Here is an excellent illustration of the contingencies to be met with in carrying on work upon the Mississippi River. Work which, under favorable circumstances, cost 97 cents per cubic yard, cost, under other circumstances, $2.90, or three times as much. The character of the work during the two periods was the same, and the season of the year was the same. The only difference in the circumstances came from the operations of nature, which could not be foreseen. It is plain that all estimates of cost made in advance can be no more than approximations.

For details of the work, see Appendix 12.
The expenditures were $34,000.

SUPPLY DEPOT.

For the better protection of the public property from petty depredators a board fence was constructed upon the northern and western sides of the yard, at a cost of $160 34. All of the smaller material used upon the works, such as rope, iron, wire, spikes, &c., and all subsistence stores were stored at the depot and issued as required. Many miscellaneous constructions and repairs were made, for details of which see Appendixes 1 and 13.

EQUIPMENT.

The hull of the steamer Anita having become unserviceable, her machinery was transferred to a new hull built for the purpose by Messrs. Howard & Co., at Jeffersonville, Indiana. The new boat has been named the General Gillmore. She is 140 feet long and 28 feet wide, and has been provided with every convenience for doing the work required of her. Her total cost, including three new steel boilers and outfit, thorough repair of the old machinery, and renewal of certain parts of it, was $20,171 24. The other principal additions to the equipment during the year were the construction of twenty-two portable buildings for quarters, &c., and nineteen small flats and the purchase of three second-hand coal barges.

A special record is kept in which the equipment is treated as so much unexpended appropriation. Each work is charged for the use and repair of such as may be employed upon it. The amounts given in this report as expended at each locality include the wear and tear of equip

ment.

The present valuation of the property remaining to be distributed in the future is given in the last column of the following table, in which are given also its valuation at the beginning of the year, the sums which

have been expended upon it, and its estimated deterioration during the

The telephone line constructed last year to the mouth of the Meramec was extended to Bushberg for the purpose of communicating with the work at Foster's Island. The price agreed upon with the Bell Telephone Company of Missouri for this extension was $1,932 for the first year and $655.20 for each succeeding year.

SUBSISTENCE.

The methods adopted for providing the force with subsistence are described in Appendix 14. The average cost of subsistence for each man per day during the spring of 1883 was 44 cents, including all expenses connected with the purchase, issue, and preparation of the supplies.

PILE-DRIVING.

As the driving of piles constitutes the largest single item of expense in the works of construction, it is important that the machines used for that work and the organization of the men engaged in it should be as perfect as possible. First Lieut. F. V. Abbot, Corps of Engineers, was assigned by my order of June 10, 1882, to a special study of the art of pile-driving in sandy soils, and made an elaborate series of observations, from which some interesting and valuable conclusions may be drawn. He ascertained that of $38,689.95 expended for labor in driving 20,000 piles, $14,255.94 was consumed in placing the driver in position. The conclusion is that a driver which will require least moving will, other things being equal, be most economical; or, in other words, that a driver furnished with several sets of leads promises good economical results. After careful observation of the steam hammer in use upon pile-drivers working at Chicago, Lieutenant Abbot concluded that there was little or no advantage in that form of hammer. He ascertained that the rapidity of penetration of piles sunk by the water-jet and hammer combined is remarkably uniform when the average of a great number of piles is considered, and when the depth does not exceed 16 feet, the rate being about the same for the last 2 feet as for the first two. His report is given in full as Appendix 15.

5455—E 83————75

GAUGES.

The gauges at Grafton and Gray's Point were read daily. Their records are appended marked 16 and 17, respectively. The gauge at Alton was discontinued, it having been observed sufficiently long to give with accuracy the slope of the river between the mouths of the Illinois and Missouri, and there being no other necessity for a gauge so near to that at Grafton.

NAVIGABLE DEPTH BETWEEN SAINT LOUIS AND CAIRO.

The reports made to the association of Saint Louis and New Orleans pilots by its members have been transferred to me as in former years, and from them has been made a record of the depths found upon the bars between Saint Louis and Cairo throughout the year. So much of it as covers the low-water season is herewith transmitted, marked 18. As explained in former reports, strict accuracy is not claimed for any one measurement. The record, to be of value, should be taken as a whole; several day's measurements, and the gauge records, being considered together. The low-water season extended from a little after the middle of August until navigation was suspended by ice in December. The lowest stage reached was 1.9 feet above standard low water. The least depth reported and not contradicted was 5 feet and was found at Sulphur Springs, Forest Home, Kinney Point, and Jacket Pattern. A depth of 5 feet was found at Cornice Island, Perry T. H., Liberty Island, and Crawford's. In all cases the least depth was found in October when the river was at a stage more than 3 feet above standard low water. The least depth found throughout the 21 miles of river between Saint Louis and Kimmswick over which the works of improve. ment have extended was 8 feet.

MISSISSIPPI RIVER COMMISSION.

The river and harbor act of August 2, 1882, required that the sums appropriated by that act for improving the Mississippi River below the Des Moines Rapids should "be expended by the Secretary of War in accordance with the plans, specifications, estimates, and recommendations of the Mississippi River Commission created by the act approved June 28, 1879, or according to such plans, specifications, and estimates of the Engineer Department of the Army, which, having been approved by the Secretary of War, may be adopted by the said Mississippi River Commission for such parts of the said river as the said commission may not have completed the survey of." In compliance with your instructions of August 28, 1882, I submitted my plans and a copy of my project for the expenditure of the $600,000 appropriated for the Mississippi from Cairo to the Illinois River, by the act referred to, to the commission with a letter dated September 6, 1882. At their session of September 13-18, 1882, the commission approved and adopted the project, and a copy of their resolution to that effect was furnished me with your letter of September 26, 1882. In the mean time the works were progressing, and they have since continued withont change in their administration.

ESTIMATE.

The estimate for the entire completion of the improvement which has been given in the annual reports from this office was made in 1875. The methods of construction upon which it was based proved inefficient

and were abandoned in 1879. There being no sufficient data for making an accurate estimate under the new methods of construction, the original estimate has, up to this time, been retained. The available data are not even now sufficient for an estimate which shall be entirely reliable, but it has become evident that the original estimate is too small. To avoid misleading Congress it is necessary to state this fact, and to make a new estimate which shall be as nearly accurate as present information will allow.

The contingencies of work upon the Mississippi are so great that any estimate based upon the number of linear feet of hurdle or other construction to be built, and the cost per linear foot, may be very erroneous. The original cost per linear foot may vary between wide limits, depending upon the weather and the stage of the river. By taking an average of several seasons an approximation to this cost may be reached, but the number of times that the silting devices may have to be repaired, or even entirely rebuilt, at any particular spot is uncertain. Evidently the only way to reach an accurate estimate is to take the cost per mile of some portion of the river which has been the subject of improvement for a number of years, where the circumstances are in general the same as those to be met with hereafter, and where the works have been entirely completed. There is at this time no portion of the river which fulfills all of these conditions. The present system of construction was first introduced at Horsetail in 1879. All other works of the same general character are of more recent date, the oldest of them, those at Twin Hollows, having been begun in the autumn of 1881. The works at Horsetail are further advanced towards completion than any others, and, though defective as a basis for estimating future cost, are the best for that purpose that exist.

The total amount that has been expended upon the improvement of the 5 miles of river known as Horsetail, under the present system and not including the cost of the original stone jetties, is $367,901.95. This includes $12,038.69 expended upon the protection of the west side of Carroll's Island. During the first two years of this work the forms of construction were largely experimental, they were undergoing modifica tion, and their cost was larger than it would be again under the same circumstances of weather and river. To accomplish the same result $350,000 would now perhaps be sufficient. The desired effect upon navigation has been attained, a wide, deep, and direct channel having been procured, but it remains to secure these results by further building up of the new banks and consolidating and protecting the new land. The cost of this is the uncertain element in the present problem. I estimate it at not less than $25,000 per year for three years, or $75,000 in all, to be added to the $350,000 already expended. This gives a total of $425,000 for improving 5 miles of river, or $85,000 per mile. The forms of construction upon which it is based are applicable to the part of the Mississippi below the Missouri.

Between the Missouri and the Illinois other forms are used, and all circumstances of foundation, velocity of current, &c., are different. For this part of the river $37,500 per mile would, I think, be a reasonable estimate.

The distance from the mouth of the Missouri to the mouth of the Ohio is 205 miles. Of this distance 18 miles, from Gingrass Creek to the foot of Carroll's Island, has been improved; 14 miles from Carroll's Island to Bushberg, and 5 miles from Minton Point to Cape Girardeau will reach a stage of improvement with funds now available, which may, for present purposes, be considered half done, and about 16 miles in all