AT NEBRASKA CITY, NEBRASKA. REPORT OF MR. ARTHUR S. POTTER, ASSISTANT ENGINEER. NEBRASKA CITY, NEBR., July 1, 1883. MAJOR: I have the honor to report the progress of work towards the ultimate improvement of Missouri River, at this point, for the fiscal year ending June 30, 1883. Your instructions, dated September 7, 1882, were received September 9, informing us of the availability of $32,182 for operations at Nebraska City, Nebr., and Eastport, lowa. Accordingly, repairs to plant were made which consisted in rebottoming and decking four 12 by 50 foot barges, and side raking and altering the 80 by 16 foot barge, received with property from Plattsmouth, Nebr., for use in putting in mattress. The revetment, ordered in instructions, to be placed in the bend above Eastport, was begun at a point 6,900 feet above the "point" or "landing," with a construction thought to be suitable and necessary to prevent, for a season, the channel from working behind it, called a HEADER. On September 25 grading for the header was begun. It covers an area of 7,500 square feet. Beginning at the point A (see sketch) it runs 300 feet on the shore line AB to B, at right angles to the shore at A, thence from B, 200 feet to C, thence to a point D, 300 feet from A, measured along shore. This area was excavated as A contract was let for the excavation at 8 cents per cubic yard, but was afterwards settled for 3,3724 cubic yards at 8 cents, $269. 80. After the excavation was completed a mattress of willow brush was woven 12 inches thick over the whole surface; upon this was placed about 4 inches of earth, and over this another mattress woven 12 inches thick, into the texture of which two wire nets were incorporated as a basis of strength. Upon the last mattress rock were placed and attached to it, to the amount of 200 pounds to each 36 square feet of surface; then, over all, about 10 inches of earth, to prevent the brush from becoming brittle. To the nets and upper mattress of the header was securely attached the mattress extending 100 feet into the river at low water. REVETMENT. We have completed during the year, besides the header, 5,100 linear feet of revetment, consisting of a mattress of willow brush 150 wide and 12 inches thick, into the texture of which was incorporated a wire net. One hundred feet of the width of the mattress was in the water at a 4-foot stage, and 50 feet covered the bank, which was sloped 1 to 24. GRADING BANK. Three hundred feet of bank was graded and included in cost for excavation of header; 1,523 feet was graded by contract, at 30 cents, and 675 feet by day labor, at 284 cents per linear foot of bank. During the spring work 2,660 feet has been graded at a cost of only 19 cents per foot. The spring slope was to a higher stage of water, and therefore less material moved per foot. BRUSH. We have been particularly fortunate this year in being able to obtain a fine quality of brush, and a large portion of all that was used within 1 mile from the location of the header. The total expense at first for getting it to the location of the work did not exceed 20 cents per cord, and at last, when boating was necessary from the island, 75 cents, giving an average expense as follows: 6,875 cords, at .4352 + per cord = $2,992.58. ROCK. Three contracts were let during the year for rock, the weight of individual pieces in no case to be less than 75 pounds or more than 200 pounds. The first contract cov ered the delivery of 256.46 tons at 50 cents per ton, niched ready for bailing. The contractor soon found that the price was too small, which brought into existence a second contract at 70 cents per ton, under which 718.58 tons were delivered. For spring work a third contract was let, covering not to exceed 800 tons, niched, bailed, and loaded. Under this arrangement 780 tons were delivered, at $1.15 per ton. Besides the rock received by contract, there has been used on the work about 1,000 tons-611 tons quarried during the year by day labor, and 389 tons previously on hand-making a total of 2,755 tons used, of which we have paid for 2,366 tons at $1.2025 $2,845.23. The price per ton above includes every expense except transpor tation. Rock on this reach is necessarily expensive, owing mainly to the heavy stripping, which is from 8 to 20 feet in depth, several feet of which is soapstone, and requires the continuous use of pick and mattock. WIRE NETTING. This work has been the subject of considerable experiment. The fact that the twist connection at the intersection of meshes was not all that could be desired has for some time been recognized. With this joint it is impossible to make square meshes and have the strands in continuous straight lines. With a view to a more satisfactory joint we have experimented on several intersections, as Figs. 1 to 9, Plate II, the most successful of which is that shown in Figure 9, "Weavers' knot." The ap plication of this knot to the intersection of wires, was made by my assistant, Mr. Crow its value was immediately recognized, but it was thought that the process of manufacture would be too slow and complicated to render it desirable. Experience, however, has shown its utility. The laborers themselves, although working slowly at first, became so expert in a short time as to make over their hands all the curves and loops necessary for the knots while moving from one intersection to the next, and this, too, with strands made of three No. 12 wires twisted together. A net made of single wire strands could be manufactured with greater ease and rapidity. The elements of practical value of the "Weavers' Knot" are three, viz: 1. There is no possibility of slip, on whichever strand the strain may come. 2. It admits of square or rectangular meshes, each strand following the same straight line of direction. 3. If there are equal strains on each strand, experiment has shown that a break will occur no sooner or easier in the knot than elsewhere. Galvanized wire should in all cases be used, as the difference in value of the wire is much more than made up by the rapidity of manufacture. SURVEYS. This Beginning October 4, a low-water survey was made from the head of "Keg Creek Island" to the Missouri State line, covering all bars and changed shore lines; also, sections taken on established ranges, about each mile over the whole reach. has been carefully platted to a scale of 1,000 feet per inch. At the beginning of this survey gauges were set at Pin Hook, Jones's Point, and Minersville, and each read continuously during the period of the survey. These readings, together with those of Wyoming and Nebraska City gauges for the same time, will give notes covering the NEBR. MISSOURI RIVER IMPROVEMENT, NEBRASKA CITY, A. S. POTTER, Engineer in charge. Under direction of Major CHAS. R. SUTER, Corps of Engineers, U. S. 4. REAR VIEW OF MATTRESS BOAT. |