THE NILE KESERVOIR DAM AT ASSUAN. 533 



to 35,000,000,000 cubic feet of water. Fortunately the conditions of 

 stability- laid down by the Jnternational Connnission on the initiative 

 of Si<inoi- Torricelii were so severe that I was able to design a dam 

 nominally capable of lujlding* up 35,000,000,000 cubic feet of water, 

 hut actually strong- enough to hold up 70,000,000, 000."' 



The dam i> located 5 miles stjuth of Assuan, or about 550 miles south 

 of Cairo, at the head of the first cataract. At this point the Nile falls 

 about 16 feet in 4 miles, the ))ed of the river ])eing granite rtjck. The 

 fall is so sligiit that the cataract throug-h most of the year is practically 

 no more than rapids. The Nile boats go down the rapids and are 

 towed up at nearly all stages of the rivei". 



The dam is almost exactlv one and a (|uarter miles Irjng and has a 

 maximum height above the foundation of 147 feet. The foundation 

 was laid upon solid granite throughout. The rock was decomposed to 

 a great depth; in some cases as nmch as 45 feet were remo\ed before 

 solid rock was found. This large amount of excavation increased the 

 actual cost of the work beyond the original estimate. No drill holes 

 were made in the underlying rock l)efore the v.ork of construction 

 was commenced, so that the information upon which the original esti- 

 mate was made was not as complete as it might have been in this 

 respect. The dam is :23 feet w^ide at the top and allows for a roadway 

 13 feet wide, on which is laid a narrow-guage track. The rock is 

 granite, quarried near by, and laid in Portland cement. It is said that 

 ♦jO0.<m»0 barrels of cement were used in this masonry — an order suffici- 

 ently large to materially affect the market value of cement in England. 

 It is interesting to note that although the volume of masonry is very 

 large, yet it approximates only one-fourth of the cubic contents of the 

 Great Pyramid near Cairo. 



The building of the dam was rendered especially difficult l)y the 

 higli floods which annually come down the Nile. The normal difl'er- 

 ence in level between high and low water at Assutin is 38 feet, and 

 work could be carried on to advantage only during low Avatei'. 



To expose a portion of the river bed, dikes were ])uilt. and the por- 

 tion of the bed thus laid bare was excavated to solid rock. The foun- 

 dation was then built up to about normal flood level, and a new portion 

 of the l)ed dried. In this manner the foundation was completed across 

 the river, and later the superstiiicture was added to the desired height. 

 As will be seen l)v the accompanying illustrations, there Avas a great 

 deal of hand labor, as many as 12.000 workmen being employed at one 

 time, about one-tenth of whom were skilled Italian masons. 



The sluices are arranged in tiers at three levels. Iron gates of the 

 Stoney system, running on rollers in steel grooves, permit the closing 

 or opening of all the sluices in a very few moments, the gates being 

 suspended on steel wire cable and Sailing by their own weight. The 

 winches are operated by hand. A few of the sluices are lined with 



