Engineering Wonders of the World
Volume I

THE NILE DAMS AND THE ASSOUAN RESERVOIR. 393 level originally proposed by 8 metres (25 feet) —that is, from 114 R.L.* to 106 R.L. Although at first the site chosen for the great dam was much criticised, its suitability was fully confirmed by later investigators and surveyors. It is true that the rock formation required the foundations to be sunk 40 feet deeper than was originally proposed ; but the general formation of the surrounding country and the character of the river, bounded as it is here by the granite hills, more than coun- terbalanced all difficulties. Moreover, the width of the Nile at the point chosen allowed the requisite number of sluice holes to be made in the dam ; while the fact that at low Nile the river flowed through five channels, which could be dealt with separately, simplified the method of construction. It may be as well to restate briefly what was aimed at by the engineers at Assouan. Allowing for the reduction of the level in the interests of archaeology, which The Dam. .. „ meant a sacrifice or 1,500 million tons of water, it was to form a reser- voir impounding 1,000 million tons of water, which could be released when required, and added in due season to the lessening flow of the Nile. This purpose was accomplished within four and a half years of the beginning of work upon the project, which took the form of a single dam of red granite, 1| miles long, running E. by N.E. and W. by S.W. across the river, pierced by 180 sluice open- ings capable of passing the maximum flood discharge of the river, or 15,000 tons of water per second. Red granite has been quarried near Assouan from the earliest times. The casings of the great Pyramids were made of it. All the stonework used in the construction of the dam and of the navigation locks came from this neighbourhood; some was taken from the ancient quarries hard by, some from great boulders broken up near the dam site. * 114 metres above sea level. The maximum height from foundations, which, of course, varies considerably, is 130 feet ; and the level of the water impounded is 67 feet higher than that of the river below. The face work is built of coursed rock-faced ashlar ; 130 sluices are lined with finely- dressed ashlar, the remaining 50 with cast- iron plates ; the hearting consists of rubble ; and all is set in mortar made of Portland cement sent out from England. The total weight of the masonry is calculated at over one million tons ; of the sluices and other steel work, at 6,400 tons; and of Portland cement, at 75,000 tons. By contrast, the weight of the masonry in the Great Pyramid of Cheops is estimated at five million tons. It may interest the reader to know that the amount of water impounded is eighteen times that contained in the Vrynwy Reser- voir for the supply of Liverpool, and ten times that stored in the great Croton Reservoir re- cently completed for the supply of New York. In March 1898 the contract * for the con- struction of the dam was signed. The first year was occupied mainly in preliminaries— building houses for the work- men, constructing lines of rail- Work ; commenced, way to the quarries and to the main, line, opening up the quarries, and in doing a little permanent construction on the right bank abutment. H.R.H. the Duke of Connaught laid the foundation stone on Feb- ruary 12, 1899. During this year temporary stone dams were thrown across four of the summer channels, and other work of lesser importance was undertaken. These stone sudds or temporary dams were the key to the whole operation of building the foundation. Put across the k i 7 7 n. Sudds, various channels, below the site of the great dam, they served to stop the rush of water through the channels when the flood * The contractors were Messrs. John Aird and Co. All steelwork and ironwork in the sluices and lock gates, etc., were supplied by Messrs. Ransomes and Rapier, Ltd.