Engineering Wonders of the World
Volume I

THE NILE DAMS AND THE ASSOUAN RESERVOIR. 395 Fig. 11.—EXCAVATING FOUNDATIONS IN WEST CHANNEL BOTTOM. it was feared that the granite in the bed of the channels might be deeply fissured, and the fissures filled with light and easily- displaced material. The operation of pump- ing out, therefore, was one to arouse anxiety in all concerned. If the not unreasonable apprehensions of the engineers were real- ized, there would be a delay of some two to three years or more in the completion of the great task. As a precaution, twenty- four 12-inch steam centrifugal pumps were sent out from England. At last, when the test was applied to the Bab-el-Kebir channel, it was found, to the relief of all, that the fis- sures were filled, according to the late Sir Ben- jamin Baker, “ with practically impermeable material,” and the leakage was so small that only two 12-inch pumps were required to keep it down. The surface of the beds of the channels having been cleared of loose stones and large boulders, good solid rock was sought whereon to base the foundations. Owing to the defective character and rotten condition of much of the rock, especially in the beds of the deeper channels, the amount of excavation necessary was in some cases five times more Pro^ress and than had been expected, and ComPletion- the foundations had to be sunk 40 feet deeper than was originally intended. The unsound surface granite was removed with the pick- axe, and that beneath by blasting. The foun- dations were begun and carried on until the rise of the river stopped work. Also, during the course of 1900, two sudds across the re- maining or western summer channel were started. The fourth year saw the foundations