gaged in preparing plans for the work and in making test borings for the new conduit, with the diamond drills described on page 219. By May 1884 the plans had been sufficiently matured to enable the engineers to stake out the final location of the aqueduct, and fieldparties were organized for this purpose. By the end of the year the Commissioners were ready to commence the construction of the new aqueduct. Prior to letting the contracts, the work was divided into seven divisions and the engineers mentioned below placed in charge. District. DIVISIONS OF THE NEW CROTON AQUEDUCT. Length, Miles. 4.92 3-54 5.36 4.62 4-57 5.00 Northern... After the Aqueduct Commission was changed by chapter 337 of the Laws of 1886, the Engineering Department was reorganized as follows: The work was divided into a northern and a southern district, which were subdivided into five divisions. The Aqueduct Commissioners appointed on July 27, 1886, J. Imbrie Miller, Principal Assistant Engineer in charge of the Northern District, and Charles Pugsley, Principal Assistant Engineer in charge of the Southern District. Southern..... Engineer in Charge. J. M. Wolbrecht. Alfred Craven. The former served in this capacity until November 24, 1888, and the latter until May 31, 1887. The engineers placed in charge of the different divisions are mentioned in the following table. E. S. Gould. F. W. Watkins. Edward Wegmann. Engineer in Charge. 3 4 7-53 J. B. McIntyre. 5 5-34 Division Engineer McIntyre resigned on April 27, 1887, and was succeeded by S. F. Morris. The work in connection with the construction of the east-branch reservoir (known as Double Reservoir I) was organized as a sixth division in 1887, Mr. George B. Burbank being placed in charge. He resigned June 17, 1891, and was succeeded by Mr. Walter McCulloh, who had been connected with the work from the beginning as Assistant Engineer. As the work on the new aqueduct drew near its end, some of the division engineers DIVISIONS OF THE NEW CROTON AQUEDUCT. (No. I 2 7-55 6.68 6.02 resigned and others were transferred to the new reservoirs. When the construction of the new aqueduct was practically finished, the Aqueduct Commissioners divided the work on October 13, 1892, into four divisions as follows: DIVISIONS OF THE RESERVOIRS CONSTRUCTED BY THE AQUEDUCT COMMISSION. Division. New Croton Dam division. Carmel and Purdy's Dams division..... Brewster's Dams division.. Croton River division * Engineer in Charge. Alfred Craven. Walter McCulloh. During the whole period of the construction (from January 1884 to date) Mr. F. S. Cook, Assistant Engineer, has remained in charge of the important Draughting Bureau. After Mr. Fteley's resignation as Deputy Chief Engineer on July 31, 1886, this position was left vacant until July 6, 1887, when Mr. George S. Rice, who had been engaged on the construction of the new water-works and the improved sewerage system of Boston, was ap pointed Deputy Chief Engineer. Mr. Rice occupied this position until he resigned on July 15, 1891. * Embracing the changes of roads and bridges for the new Croton reservoir and the Muscoot Dam. PRACTICAL DETAILS OF THE CONSTRUCTION OF THE NEW CROTON AQUEDUCT.* Contractor's Plant.-A detailed statement of the machinery and appliances used at the different shafts of the New Croton Aqueduct is given in the table on page 292. Descriptions of the principal machines and appliances used will be found on pages 213 to 232. The cost of the plant and buildings required for one shaft and one mile of tunnel was about $30,000, as will be seen by the following approximate estimate: ESTIMATE OF COST OF PLANT AND BUILDINGS FOR ONE SHAFT AND ONE MILE OF TUNNEL (TWO HEADINGS). CHAPTER VII. $3,000 00 5,200 00 200 00 1,200 00 1,100 00 450 00 1,250 00 500 00 300 00 800 00 1,000 00 875 00 220 00 5,000 00 200 00 3,300 00 1,500 00 1,000 00 650 00 190 00 600 00 160 00 $28,695 00 NOTE.-The above estimate was furnished by Messrs. Denton, Breuchaud & Co., the superintendents (sub-contractors) for section 8. * Some of the facts given in this chapter have been taken from the series of articles on the construction of the Croton Aqueduct that appeared in the "Engineering Record" of 1889 and 1890. The approximate cost of the compressed-air equipment for one shaft for running about twelve drills for tunnelling was about as follows: COST OF COMPRESSED-AIR PLANT. Twelve rock drills, 3-in., with tripods, drill-columns, drill-steels, and hose, at $378.. One air-receiver, cylinder 48" x 12", complete... Two horizontal boilers, 60" x 14', complete, with iron fastenings, grates, gauges, valves, injector, and stack, each 70 H. P., at $1210 each. Pipe and fittings for connecting boilers and compressor and air-receiver.. Main air-pipe and distributing pipes, and fittings (variable), say... Cost of material and labor for setting boilers, 22,000 bricks, etc. (estimated). Cost of material and labor for connections and starting plant...... Freight and incidental expenses dependent upon the distance from New York, variable, estimated, 75,000 lbs., at from 10 to 15 cents per cwt., say.... $4,536 00 3,060 00 279 00 2,420 00 125 00 250 00 400 00 175 00 100 00 112 00 Total cost... NOTE. This estimate was furnished by the Ingersoll Drill Company of New York. Four kinds of drills were used: Ingersoll, Rand, Sergeant, and Rattler. They are described on pages 215 to 219. Air-compressors were placed generally at each shaft. There were, however, two exceptions to this rule. The compressors for shafts o and I were placed together, near Croton Lake, to secure a supply of pure water for the boilers. The air was conducted to these shafts in a 4-inch wrought-iron pipe having screw-joints. This pipe was laid on the surface and carried to the foot of shaft No. 1, where it was continued by branch-pipes to the north and south heading. The maximum distance from the compressor to the drills was about 1 miles. On Manhattan Island the compressor-plant for shafts 27 to 32, inclusive, was concentrated at shafts 28, 29, and 31, the air-pipes (wrought-iron pipes 3 to 4 inches diameter, laid generally in the gutter of Tenth Avenue) being connected so as to equalize the supply for the different shafts. Three styles of compressors were used, viz.: the Ingersoll, the Rand, and the Norwalk. (For description see pages 213 to 215.) From the compressor, the air, raised to a pressure of 80 to 100 pounds per square inch, was conducted first to a cylindrical wrought-iron receiver having a diameter of 3 to 5 feet and a length of 8 to 14 feet. The object of the receiver, which was placed generally out-ofdoors, was to equalize variations in the pressure and delivery of the air, and to condense the moisture it contained. The latter object was especially important for the Ingersoll compres sors, in which a spray of water was injected directly into the air-cylinder. In the receivers used for these machines the air was made to pass through a large number of tubes surrounded by water. These tubes were not required in the receivers for the other compressors. Cocks were placed at the bottom of the air-receivers for drawing off the condensed water. From the receiver the air was conducted in wrought-iron pipes (usually 3 to 4 inches in diameter) to within 100-200 feet of the heading. The pipe was continued by a rubber hose of the same diameter (the "bench-hose"), which was covered with canvas or marline to .$11,457 00 protect it from wear The hose terminated at a "manifold" (see Fig. 23), which was usually placed at the foot of the bench. From the manifold the air was distributed to the different drills by means of small hose-pipes 1 to 2 inches in diameter. A stop-cock was provided at the manifold for each hose. FIG. 23. MANIFOLD. The bench-hose, manifold, and small hose-pipes could easily be moved to one side during the blasting. Electric-light Plants. The dynamos and open arc lamps were furnished by the Thomson-Houston Electric Co. of Boston, Mass., the Schuyler Electric Co. of Mid 12'3" FIG. 24.-HEADING DRILL-HOLES. FIG. 25.-BENCH DRILL-Holes. FIG. 26.-BENCH DRILL-holes. dletown, Conn., the Bell Electric Co., the United States Electric Lighting Co., and the Brush Electric Co., the last three companies having their offices in New York. An electric-light plant was placed at each shaft, except on sections 13 and 14, on Manhattan Island, where a thirty-lamp dynamo at shaft 30 gave light to shafts 27-32, ooth inclusive, the wires being brought from shaft to shaft by attaching them to the telegraph poles on Tenth Avenue. |