TABLE NO. 7.-Seventh measurement of base line, East Base to West Base. Weather: Bright sunshine, conditions unfavorable. Began at 3.18 p. m., finished at 4.02 p. m., November 15, 1904. (Rejected.) 2 to 1.. 1 to West Base 17 to East Base...... East Base to 16.. 16 to 15.. 15 to 14. 14 to 13. 13 to 12. 12 to 11.. 11 to 10. 10 to 9.. 9 to 8. 8 to 7. 7 to 6.. 6 to 5.. 5 to 4.. 4 to 3.. 3 to 2. Station. West Base to 1 1 to 2.. 2 to 3. 3 to 4.. 4 to 5.. 5 to 6.. 6 to 7. 7 to 8.. 8 to 9.. 9 to 10. 10 to 11.. 11 to 12. 12 to 13. 13 to 14.. Station. 14 to 15. 15 to 16.. 16 to East Base... East Base to 17.... 210. Average tempera- Set back. Thermometers. Average 120. 1 61.5 64.0 63.0 66.0 61.0 62.5 61.5 64.0 60.5 61.5 62.0 63.5 61.0 63.0 61.5 63.5 61.0 63.0 61.0 64.0 61.0 64.0 61.5 62.5 60.0 61.0 59.5 60.0 59.0 61.0 59.0 60.0 60.0 63.25 63.00 61.00 63.25 61.5 60.0 61.25 60.00 61.50 63.25 62.50 63.0 62.1 63.75 61.00 60.00 61.95 Total. 60.00 61.25 59.50 60.00 58.75 60.50 59.75 60.25 59.75 60.25 60.25 59.75 58.25 57.50 57.75 57.25 58.00 Inches. 59.34 a Average after applying index error. TABLE No. 8.-Eighth measurement of base line, West Base to East Base. Weather: Fair, sun nearly set, considered favorable. Began at 4.08 p. m., finished at 4.53 p. m., November 15, 1904. Inches. Set ahead. Total. a Average after applying index error. Inches. 1.50 11.00 4.00 3.00 3.00 3.67 Set back. Set ahead. 26.17 Inches. 3.25 4.00 3.50 10.50 1.25 2.50 28.68 Distance without correction. Feet. 23.326 276.674 300.00 300.00 300.00 300.00 300.00 300.00 300.00 300.00 300.00 300.00 300.00 300.00 300.00 300,00 300.00 300.00 5,076.674 Distance without correction. Feet. 300.00 300.00 300.00 300.00 300.00 300.00 300.00 300.00 300.00 300.00 300.00 300.00 300.00 300.00 300.00 300.00 276.588 23.412 5,076.588 TABLE NO. 9.-Summary of base line measurements, East Base to West Base. Mean temperature. 1a 63.88 7a 61.95 Set back. 167 2.428 55.55 .000 2.565 5a 60.88 .000 2.315 6 54.94 2.441 .000 Set ahead. 2 66.04 .000 2.227 .014 .145 3 65.22 .000 59.34 .000 a Rejected. 2. 181 2.390 Index error of tape. Feet. Feet. 0.000 2.221 0.014 0.060 0.007 0.076 Temperature correc tion. .007 .014 .103 Proportional error of mean=1 in 2,500,000. Standard 62.0 59.6 52.6 57.5 47.0 64.5 60.0 48.7 66.5 59.0 52.8 Grade correction. Average.. Used as.. 3ds). Catenary correction Mean length =5,078.7906 .014 .000 .007 Thermomjeter No. 210. curve-d(1+80%) 64.0 62.0 54.0 60.0 49.0 66.0 62.0 50.5 68.5 61.0 54.5 .076 1 15 1 076 0.6745 | 3(pl): Difference. Time of work. 2.0 2.4 1.4 h. m. 2 30 TABLE NO. 10.-Comparison of thermometers with standard thermometer. 2.5 2.0 1.5 2.0 1.8 2.0 2.0 1.8 1.95 2.0 64.7 62.0 55.0 60.0 49.5 66.0 62.1 51.0 69.0 61.5 55.0 Thermometer No.120. Remarks Difference. 2.7 2.4 2.4 2.5 2.5 1.5 2.1 2.3 2.5 2.5 2.2 2.33 2.5 sun M M M 7. DEFENSES OF GALVESTON, TEXAS. [Officer in charge, Capt. Edgar Jadwin, Corps of Engineers.] EXTRACT FROM SPECIFICATIONS FOR SEA WALL, FORT CROCKETT RES weig ties Trenching.-A trench about 16 feet wide at bottom shall be exca Ivated along the line of the sea wall, the bottom to be 1 foot above lum mean low tide, and all material thus excavated shall be deposited back the of the site of wall as may be directed by the United States agent in eith charge, but in no case will it be required to be moved over 50 feet the except at battery sites, where it will not exceed 100 feet. and 10 s C Piling. The proposed sea wall is to be supported on pile foundation, with piles spaced as shown on plans. The piles must be green, with bark on, sound and straight, of either long or short leaf pine, free from decay, large, numerous, or unsound knots; the ends must be square and all branches smoothly trimmed off. The piles shall not vary more than 6 inches from a straight line connecting the ends, and shall not be less than 10 inches or more than 16 inches in diameter 2 feet from the butt, measured under the bark, with a least diameter of 7 inches at the point inside the bark. The piles will be sharpened before driving, and will be driven with hammer and jet until within 2 feet of the final depth, the last 2 feet being driven by hammer alone. If so ordered the piles will be cut off at an elevation of 2 feet above mean low tide, and any pile broomed or split in driving so as not to give a solid cut-off or bearing shall be removed and replaced at the expense of the contractor. All piles shall be driven plumb in the positions shown in plans, have the bark removed from the cut-off to a point 5-10 feet above mean low tide. Piling so driven will be paid for per linear foot below cut-off in completed structure. Sheet piling. The sheet piling shown on the Gulf side of the sea wall will consist of piling built up of 3 pieces 4 by 12 inches by 24 feet sized 3 by 11 inches of long or short leaf yellow pine, all pieces to be uniform in width and thickness, and bolted every 4 feet with by 11-inch screw bolts, countersunk head and nut, with a 9-inch spike driven through tongue, as directed and as shown on plan and cross section. The piling will be driven true and out of wind, with closed joints. Any piles broomed, split, or badly driven shall be removed and replaced at the expense of the contractor. The method of driving will be the same as described for the round piling, and if necessary be cut off at an elevation of 1 foot above mean low tide in a smooth workmanlike manner. The sheet piles shall be sound, free from large or loose knots, shakes, or split ends. The sheet piling will be paid for per 1,000 feet B. M. in completed structure, including all necessary bolts, spikes, etc., to hold the piling in place. Broken stone. The broken stone for concrete shall be of hard, tough, durable granite, limestone, sandstone, or other equally satisfactory stone, weighing not less than 125 pounds per cubic foot when thoroughly dry. It shall be so crushed that it will pass through a 3-inch ring. It shall be clean and free from dirt, but the particles of hard stone larger than one-fourth inch that come from the crusher shall be retained. Sand. The sand used in the concrete for the sea wall shall be clean, sharp, fresh water sand, hard and durable, free from dirt, clay, and vegetable matter. Not more than 35 per cent by measure, when dry, shall pass through a No. 50 sieve of 2,500 meshes to the square inch, and not more than 10 per cent by measure shall be retained on a No. 10 sieve of 100 meshes to the square inch. Cement. The cement shall be a true Portland, dry and free from lumps. By a true Portland cement is meant the product obtained from the heating or calcining up to incipient fusion of intimate mixtures, either natural or artificial, of argillaceous with calcareous substances, the calcined product to contain at least 1.7 times as much of lime, by weight, as of the materials which give the lime its hydraulic properties, and to be finely pulverized after said calcination, and thereafter ENG 1905 M -190 additions or substitutions for the purpose only of regulating certain properties of technical importance to be allowable, not to exceed 2 per cent of the calcined product. Weights. The average weight shall not be less than 375 pounds net per barrel, and 125 pounds net per sack. If the weights, as deter mined by test weighings, are found to be lower than 375 pounds per barrel or 125 pounds per sack, the cement may be rejected, or the contractor may be required to supply, free of cost to the United States. an additional amount equal to the shortage. Tests.-Tests were made of the fineness, specific gravity, soundness, time of setting, and tensile strength of the cement. Reenforcing and anchor rods.-Corrugated steel bars 14 inches square, 10 feet in length, as manufactured by the St. Louis Expanded Metal Company, were placed near the front face of the wall, as shown on plans, at intervals of about 2 feet. Anchor bars 14 inches square, 4 feet long, as above specified, will be set in the concrete base in rows, spaced about 3 feet centers, traversely to the wall and about 5-foot centers longitudinally. Also the vertical face of each section of superstructure may be required to be anchored to the adjoining section, in addition to the concrete key, with similar bars placed as directed. These rods will be paid for per pound in place in completed structure. Concrete. The concrete shall be composed of the broken stone, sand, and cement heretofore specified. (Batch-mixing machines, of the Smith patent, one 1 yard, one yard were used.) The ingredients shall be placed in the machine in a dry state and in the volume speci fied, and thoroughly worked, after which clean water shall be added and the work continued until the wet mixture is thorough and the mass uniform and of such consistency that no tamping is necessary. The mixing shall be done as rapidly as possible and the batch deposited in the work without delay. All concrete shall be mixed in the follow ing proportions: One barrel of Portland cement, 375 to 380 pounds net; 114 cubic feet of clean sharp sand, and 27 cubic feet of broken stone. The cement shall be measured in original packages. The sand and broken stone must be actually measured in bulk. No counting of shovels full or other approximations will be allowed. All concrete shall be mixed in small and convenient quantities and immediately deposited in the work. It shall be laid in horizontal layers, not exceeding 9 inches in thickness. In no case shall concrete be permitted to be placed in the work if it has begun to set. Layers of concrete must not be tapered in wedge-shaped solids, but must be built with square ends. The concrete must be so thoroughly compact that there shall be no pores or open spaces between stones of which it consists that are not thoroughly filled with mortar. The concrete shall be deposited continuously in the work, and all surfaces upon which concrete has to be laid must be wetted and sprinkled with neat cement before the concrete is so depos ited. Work, when started on a section of the wall above elevation 4 feet above mean low tide, should be continuous and so performed that no lines of cleavage shall be formed by a portion of the mass setting before an adjacent portion. After excavation is made, piles and sheet piling driven and cut off at proper elevation, as shown on plans, and the bark removed from the portion of pile to be embedded in the concrete, so that it shall be entirely free from bark and broomed edges, the base of the wall shall be built continuously and to an elevation 4 feet above mean low water, leaving the two 6-inch by 4-foot recesses in top of base of wall, as shown on plans, and after base shall have set, the upper portion of the wall shall be constructed in sections, alternately, as shown on plans, and when these sections shall have set sufficiently to allow the casings to be removed, the intermediate sections shall be built. Before starting concrete of the sections above elevation 4 feet above mean low water, the top of base of wall shall be thoroughly cleaned and washed off and dusted with neat cement (or otherwise, as may be directed) just in advance of concrete being put in. The riprap shall be placed in front of the wall, as hereinafter specified, either after pile driving is completed or after pile driving and base of wall are completed. In any case, however, the riprap shall be in place before the wall is carried above elevation 4 feet above mean low tide. Molds for concrete.-Substantial plank shall be provided by the contractor to form the concrete to the exact shapes and dimensions shown on plans, and all surfaces of the forms which come in contact with the concrete shall be thoroughly oiled before the concrete is deposited. They shall be of a substantial character; if made of plank, dressed one side and two edges, and the frames holding them shall be of sufficient strength so that they will be practically unyielding during the process of filling; 2-inch plank supported every 4 feet will be satisfactory. They shall be so constructed that the inner surfaces of the mold shall be as nearly as possible perfectly smooth, without crevices or offsets, and practically water-tight. When the molds are used more than once they shall be thoroughly cleaned and oiled before using again. The wall shall be finished in a workmanlike manner and to the exact dimensions and elevations shown on plans, care being taken that no pieces of the broken stone shall appear in the finished face. The top of the wall will be floated and troweled. After casings or molds have been removed and wall completed the line of vertical contact between the sections shall be tool pointed, as directed, on the front and back sides of wall. Should there be found on removing the casings or molds any small pits or voids on the exposed surfaces of the wall, such porous places shall be neatly stopped with pointing mortar composed of one part cement and one part sand mixed in small quantities, to be used before it shall commence to set. No plastering of any surfaces will be allowed. Riprap protection. For a width of 27 feet from the sea face of the wall outward the beach shall be covered with a layer of riprap 3 feet in thickness. The riprap shall be sound, durable, hard, tough stone, weighing, when thoroughly dry, not less than 125 pounds per cubic foot. Not less than 50 per cent of the stone, by weight, shall be in pieces each weighing not less than 200 pounds, and at least 20 per cent shall be in pieces each weighing not less than 1,000 pounds. Stones weighing less than 15 pounds, and dirt, shall be excluded. RESULTS OF TESTS MADE TO DETERMINE THE STRENGTH OF CONCRETE WHEN CEMENT IS MIXED WITH SAND, CLAY, AND LOAM IN VARYING PROPORTIONS. The cement was "Double Anchor" German brand, the sand standard quality; the clay was taken from the cutter of a dredge working in Galveston channel; the loam was heavy black soil from the |