NEAR ROCHEPORT.

A bankhead, 1 D, designed to hold the channel as it then existed, was built in the right bank above Rocheport.

The rock for its construction had been gotten out in October and stored at head of Diana Bend. In April erosion of the bank threatened the safety of the rock, and it was decided to at once build the bankhead.

It was built between April 19 and May 4 on a modified plan, which may be briefly described: A circular arc of 350 feet radius, in a plane 10 feet above standard low water and tangent to the bank, marked the outer edge of a pile of loose stone, in section, a parallelogram of 15 feet base and 10 feet altitude. The central angles were 50° above and 40° below the directrix. Soon after finishing work on the bankhead, it being incomplete for lack of stone, a rise in the river brought about very rapid erosion, and surveys so far made indicate that the stone was undermined and fell in masses.

There can scarcely be any doubt but better results would have been obtained had the stone section conformed more nearly with the original plan, retaining its sectional area of 150 square feet, but kept at 5 feet in height and lowered nearer to the plane of standard low water.

HOWARDS BEND ABOVE ST. CHARLES.

Three bankheads, 4 F, 5 F, and 6 F, were built in this bend, all in accordance with the general design, but all curtailed in length, the central angles being 80°, two having 50° in the upper arm, and 5 F having but 45°.

The natural bank in Howards Bend is very high, and at a depth of 4 to 6 feet above standard low water was found to be largely composed of blue clay or gumbo. Wet weather set in while 5 F was building, and the ground sloughed badly in making the excavation. The work from these causes became expensive, estimates were exceeded, and the work had to be curtailed in amount.

At the present time but little change has occurred at 4 F, and 5 F has apparently taken care of the caving above it.

Bankhead 6 F has been entirely uncovered, and also degraded from the upper end to near the directrix to a level of 12 feet above standard low water, to which height only the paving of the slope had been carried, on account of the exhaustion of funds.

Surveys to determine the disposition of rock and other details must await a lower stage of water.

For further details of the work see report of Assistant Engineer S. Waters Fox, Appendix E.

SYSTEMATIC IMPROVEMENT OF FIRST REACH.

The necessity which arose for widely separating the plant to carry on works of improvement at detached places in accordance with the appropriation acts of 1896 and 1897 rendered the maintenance of the two boat yards, which had been established at Ewings Landing and Gasconade, only 34 miles apart, inconvenient and exceedingly expensive. The Ewing boat yard was therefore abandoned during the month of July, all the serviceable property transferred to the Gasconade yard, the unserviceable property condemned and destroyed or sold, the ground occupied at Ewings returned to its owners, and the two divisions merged

into one, thereafter to be known as the Gasconade Division. It became necessary to enlarge in some degree the storage space at Gasconade, and also to renew the pile supports of much of the old ways to provide for the increase of plant requiring storage.

GASCONADE DIVISION.

The operations of the year comprised earth excavation and embankment involved in the approved project for a new junction of the Osage and Missouri rivers, dike construction and repair, the construction and placing of a device in the form of a reversed abatis for inducing deposits on bars or in shallow water, the extension in length and supply of additional stone to the bankhead in Chamois Bend, care and repair of plant, surveying, and special examinations, the preparation of maps, reports, and projects, and miscellaneous incidental work. The work was done under an allotment of $100,000 for continuing the systematic improvement of the First Reach, in accordance with the project approved by the Chief of Engineers August 13, 1897, together with $5,000 transferred from another allotment, as heretofore stated.

NEW JUNCTION OF OSAGE AND MISSOURI RIVERS.

The work carried on during the year under this project included making a cut through Osage Point and using the excavated earth in an embankment immediately below and adjoining Dike 19 A, these two structures to form, when completed, the extended left bank of the Osage River to its junction with the Missouri; the cutting of an initial V-shaped ditch through the bar accretions extending from the main bank to the Missouri, the partial revetment of the earth embankment, and the rescreening of Dike 19 A.

CUT THROUGH OSAGE POINT AND EMBANKMENT ADJOINING DIKE 191⁄2 a.

It was expected to commence this work early in the season, but, while all preliminary arrangement was thought to have been provided for, difficulties arose in acquiring a satisfactory title to the property taken and also the right of way privileges, which consumed so much time that it was not until September 27 that practical operations could be begun. An excavating plant of 2 steam shovels, 60 dump cars, rails, scrapers, etc., and an electric-light dynamo, with lamps were rented, and, together with a steam plant belonging to the work for operating the cars by cable, running dynamo, etc., were installed and commenced operations on the date named.

A trestle 1,875 feet in length was constructed on the line of the embankment, on which tracks were laid and trains of cars were dumped as they were loaded by the shovels.

It required nearly a month before the force of new men could be broken in, practical difficulties overcome, and a thoroughly effective organization accomplished.

During November rapid progress was made, but with the advent of December rainy weather set in, with alternate freezing and thawing, and the cost of the work became so much increased that it was decided to postpone additional work until the next season. An intercepting levee was built across the cut to prevent flow through it in its unfinished state, all work was suspended, and the rented plants were returned to their owners during December.

Initial V-shaped ditch. This work extends from the main bank through the sand-bar accretions on the line of the proposed channel, prolonging the cut through Osage Point to the Missouri River. Slip scrapers were used in making this excavation, which was carried to a depth of standard low water.

Protection of embankment adjoining 19 1-2 A.—In the design of the embankment it was intended, in order to provide for possible erosion, to revet its lower side full length and to prevent all flow along the upper side by a number of well-protected earth spurs or several rows of pile-screen work run out from the embankment to the pile work of the dike. The bad weather and lack of sufficient funds prevented any further protection work than the laying of 100 linear feet of mattress on the upper side at the stream end of the embankment, when the work was suspended.

Early in June, 1898, when the stage of the Missouri River was about 12 feet above standard low water and the accretions above Dike 19 A were submerged, it was found that the embankment was withstanding a heavy hydraulic head and that a swift current had set in on both sides, threatening its destruction. Before the caving could be checked 420 feet of its stream end had been washed away, but a revetment of 375 linear feet placed on its upper side prevented a further loss of the embankment, although its cross section had for 255 feet been very materially reduced.

Dike 19 1-2 A.-The only work done on this dike was the tightening of a few strand ties, previously under water, and attaching a close screening of poles for its full length.

OTHER DIKE WORK.

Dike XI A.-Some strand ties were tightened.

Dike XI B.-A breach of 120 linear feet made during a storm in June, 1897, was repaired and the dike completed. Later in the season the curtain of the dike was made tighter, to hasten accretions.

Dike XXIII.-A breach of 100 linear feet made during the rise of last year was repaired.

Reversed abatis.-This device having the general form of an abatis, placed in a reverse position to the flow of the current, was designed as a substitute for pile dike work in closing shallow channels.

During October five sections, aggregating 339 linear feet, were placed across a chute around the head of Hardins Island. It answered its purpose exceedingly well, and successfully withstood runs of ice and drift. Its efficiency and economy of construction will commend its use in many places.

Bankhead in Chamois Bend.-During the entire summer and fall season the line of approaching flow did not correspond with the general line of the bend above, but after passing Dike XXVIII A' the channel made a short crossing from the right bank to near the head of Hardins Island, which it followed a short distance and then crossed again, impinging on the right bank immediately above the bankhead.

During the second week in August the upper arm of the bankhead was extended 44 feet, making a junction with the caving bank, and the total central angle became 103° 26', of which 60° 38′ was above the directrix. Between limits of 264 feet and 341 feet above the directrix there was added to the outer wall of last year's work 243 cubic yards of stone, the originally intended section not having been filled out.

A considerable effort has been made to induce the flow to follow the

right bank of the river above the bankhead by masking with dikes a middle bay in Chamois Bend, by closing the chutes at the head of Hardins Island and preventing further erosion of the island by sinking condemned barges and placing of abatis, and also by attempting to wash a channel through Greasy Creek bar with steamboats, but the low stage of the river prevented any success being attained.

The main bank immediately above the bankhead has continued to recede, and for about 1,100 feet above the upper end of the structure has caved back beyond the theoretical line of recession, reaching a radius of about 1,000 feet, while from a point only 300 feet farther above the caving during the entire year has been inconsiderable.

As the bankhead stands now, it would require an extension of 110 feet of its upper arm to make a junction with the main bank, which, if accomplished, would make its total central angle 121° 16', of which 780 28' would be above the directrix.

The structure has withstood all the attacks upon it, and although conditions have not been altogether what were expected, the bankhead has prevented a large area of ground from being washed away and an undesirable channel resulting. Should, however, the approaching flow be restored to the right bank of Chamois Bend, where it is intended to be, its protective influence over further caving could certainly be manifest.

For further details see report of Assistant Engineer S. Waters Fox, Appendix F.

Plant. The only item involving a considerable expense connected with the plant was the consolidation of the two boat yards. The floating plant underwent no repair, except that which was incidental to wear and tear in service, or was made necessary by damages from storm. Nearly all the hulls belonging to the work are old and much decayed. During the year 52 hulls, many of which had been long unserviceable, were condemned by the Inspector-General U. S. Army. A number were sunk for improvement purposes at appropriate places, and the remainder burned or wrecked.

The useful plant at the present time is a small one, and much of it is in need of extensive repair. The commission will soon be required to take into consideration the subject of new floating plant.

DAMAGES TO DIKES.

There were only three dikes which received any material injury during the year, viz:

Dike 19 B.-The trail was carried away.

Dike 34.-Breached for about 70 feet near stream end.

Dike 35.-Breach of last year has widened several bents.

REMOVAL OF OBSTRUCTIONS.

The snag boat remained in the vicinity of Chamois, Mo., with a minimum crew until August 23, when she was fully outfitted and proceeded to Kansas City, arriving there on the 29th.

On August 30 a trip of inspection by some of the members of the commission was commenced at Quindaro, Kans., and the boat proceeded down the river, removing only such snags as were prominently in the way, reaching St. Louis September 6.

On the 9th of September the boat reentered the Missouri River and worked thoroughly upstream as far as Kansa sCity, where she arrived

October 12. At this point it was expected that a subcommittee of the Committee on Commerce, United States Senate, having under investigation the floods of the Mississippi and Missouri rivers and the work of the commission, would join the boat for a trip down the river, but this project being abandoned by the committee the boat left Kansas City October 28, and working down the river, arrived at St. Louis November 14. On November 20, after taking on some repair material, she left for her winter quarters in the mouth of the Tennessee River, where she was laid up on the 27th.

A considerable amount of repair work was of necessity performed on the boat during the year, the labor of which was, however, almost entirely accomplished by her regular crew. During August an entirely new fire-proof covering was laid on her roof. During the fall season the hull of the boat received two quite severe injuries on the forward knuckles, due indirectly to the extreme low stage of the river, one by swinging against a submerged stump and the other by striking bowlders while running through Sibley Bridge. These breaks were repaired while the boat lay at Kansas City.

The wooden wheelhouses and outside bulkheads, which had become much decayed, were renewed during the winter and the boat was given the usual scrubbing and painting inside and out.

The boat left Paducah to commence spring operations March 11, and arrived in St. Louis on the 19th, where, however, she was detained on account of the water being too high for effective snagging until April 6. On that date she reentered the river and worked upstream to St. Joseph, Mo., reaching there May 1, and working back she reached Jefferson City on the 12th, where she was laid up with a minimum crew. Her operations for the year included the removal of 439 snags, weighing 4,205 tons, and 2 drift piles, the cutting of 27 trees liable to become snags, and running 2,932 miles.

OSAGE RIVER.

The project for the improvement of this stream, adopted in 1871, consisted in the removal of obstructions to navigation, such as snags and leaning timber, in deepening the channel over shoals by means of dredging, and in the construction of cross and wing dams to concentrate the water over the shoal places.

The original estimated cost of the project was $230,000, but afterwards the work was made to cover more ground than was originally intended, and for a number of years past no estimate of the cost of the improvement by this method has been rendered in the annual reports. From the nature of the project, which contemplates only temporary relief from year to year and the removal of obstructions which are constantly forming anew, no definite time can be fixed for its completion and no estimate made of its ultimate cost. The improvement must be continuous, and the annual estimates must depend upon conditions as they arise.

The amount expended by the General Government under this project to June 30, 1898, is $232,135.22, of which sum $1,187.73 was expended during the past fiscal year. The result has been a temporary benefit to navigation along the river for a distance of about 245 miles above the mouth.

The construction of a lock and dam near the mouth of the river was authorized by the river and harbor act of September 19, 1890. Owing