56 



until the flood has practically disappearea and comparatively clear 

 water again flows in the Nile. 



Work on the foundation and lower parts of the dam had to be prose- 

 cuted during low Nile. The numerous channels into which the river 

 is divided at the head of the first cataract favored this work. Tempo- 

 rary dams thrown across one channel turned the w^ater into others, 

 and, by thus changing about, each part of the foundation was com- 

 pleted and put in shape so that the next flood could pass over it with- 

 out injur3% Along the west margin of the river immediately above 

 the dam it was found necessar}' to resort to riprapping. as the mate- 

 rial is rather fine and the current sets in aofainst that Inink durinsf 

 high water. The greatest difliculty in the construction of the dam 

 was to find stable material upon which to place the foundation. In 

 one of the channels the partly decomposed granite had to be excavated 

 to a depth of 60 feet below the bed of the river (PI. XXII, fig. 2), mak- 

 ing the total height of the dam at this point over 120 feet. The 

 neighboring country supplied a fine quality of granite in unlimited 

 quantities. The Egyptian Kailway coimects directly with steamers at 

 Alexandria, and cement was delivered at Shellal, within 2 miles of the 

 dam site. The contractor built light railways from the dam to Shellal 

 and to the quarries. In this wny the stone, cement, and other sup- 

 plies were brought to the point where needed and were lifted direct 

 from the cars to their final positions in the dam. The rubble masonry 

 stone of which the interior of the dam is composed Avas carried up 

 inclined planes by natives to the masons. The cement mortar for 

 this work was mixed alongside the dam and handled in the same man- 

 ner. The large dimension stone of which the face of the dam is con- 

 structed was cut at the quarry and shipped as needed. The edges of 

 the stone were protected by wooden frames, and other precautions 

 were taken to keep the corners true while the heavy blocks were being 

 handled. 



The first cost of the dam was §9,740,000* which, with interest, will 

 be paid in (>(» semiannual installments of §382,845.31 each, the first 

 payment to be due July 1, 1903. This makes the final cost of the dam, 

 including interest, §22,970, 718. (3(». The cost of the work, not includ- 

 ing the purchase of land which the reservoir covers or the repairs 

 made to the temples of Fhilae, amounts to §11.26 per acre-foot of 

 capacity. The ultimate cost to the people of Egypt, including inter- 

 est charges, will be §26.56 per acre-foot. Egypt has also raised 

 §5,746,600 for improving canal sj-stems, especially those of Upper 

 Egypt, so that the water supplied by the reservoir may be distributed. 



As the water stored by the reservoir could not serve all the land 

 which might be reclaimed in Egypt, it was decided to furnish water 

 to the areas alread}' under cultivation but which suffer from drought 

 during the months of scarcitv. That part of the vallev Iving between 



