Engineering Wonders of the World
Volume I

98 ENGINEERING WONDERS OF THE WORLD. defined point at the top of the hill and meas- ured downhill each way. One end of the board was placed on the point, and raised or lowered until the middle man said “ level.” Then the man at the outer end would drop a plumb-bob and mark the spot directly be- neath the end of the board. The board would then be reversed, the outer man would take the stake, and the stake man would drop the plumb-bob. If the plumb-bob did not hit the same identical spot that it had marked before, something was wrong, and they began all over again. Having agreed upon the pre- cise distance and marked it permanently, the new mark was taken as a base, and the process was repeated until the whole distance had been covered. It required many weeks of nerve-racking labour to complete this work. When it was finished, the plans were drawn, sent to Washington, and approved. The order came quickly to begin construction. An interesting phase of the early work was the building of a road sixteen miles in length to get into the canyon. This is one of the most remarkable highways in Subsidiary world, having in places a Works» • grade of 24 per cent, out of the canyon. Heavy machinery was hauled over this road, and a power plant was installed. Lumber and materials for buildings were brought in, and a town of 600 persons sprang up in the bottom of the canyon, where, during several months of the year, the sun shines only a few minutes each day. Another town was established at the valley portal, and more than a thousand men started in at three openings of the tunnel. A world’s record has been made on this Many work, 823 feet having been Difficulties. , . . . excavated in a single month. One gang of labourers drove 7,500 feet in one year. The enterprise has been attended by al- most every difficulty ever encountered in tunnel« excavation. Gas, cave-ins, and subterranean springs have interposed obstacles requiring the utmost care to overcome them. Unusually heavy flows of water have greatly delayed progress, necessitating the installation of heavy pumping machinery. As many as 750,000 gallons have been pumped out of the tunnel in twenty-four hours. The Gunnison Tunnel will be 30,000 feet in length, with a cross-section of 10J by 11J feet, and be cement-lined throughout. Its completion is expected in July 1909. It will have a capacity of about 1,200 cubic feet per second. Simultaneously with the work of tunnelling the mountain—all of which has been done by the Government—the contractors have completed an elaborate canal system, many miles of which have been lined with cement owing to the unfavourable nature of the ground. The Uncompahgre project contains 150,000 acres of very fine land, of which prob- ably 60,000 acres are fit for the growing of fine fruit. The orchard lands in bearing are to-day selling at from $500 to $1,000 per acre. THE SALT RIVER PROJECT, ARIZONA. In comparison with other important irriga- tion works of the Reclamation Service the Salt River project in Arizona ranks first in magni- tude, prominence, and variety of its engineer- ing features. The area to be irrigated lies in the lower valley of Salt River, surround- ing Phenix, the capital and principal city of the Territory. The project embraces approxi- mately 250,000 acres. Of this acreage, the old canals furnished an insufficient supply for less than 100,000 acres. In order to augment the deficient normal . flow of Salt River, and to increase materially the irrigable area, required an expenditure beyond the means of the people n ti • The Roosevelt living in the valley. Engineers Dam of the Government made a thorough investigation of the water supply and possibilities of storage. Their plans were finally approved, and actual construction began