48 



highway across the Nile. Onh' the Rosetta Branch of the barrage was 

 .supplied with gates. The additional head produced by closing these 

 caused enough pressure to crack the masonry of the dam. At the 

 same time water ran under the structure and a number of springs 

 appeared below. During the reign of Ismail Pasha nothing was done 

 toward repairing the barrage. Suggestions that it might be put in 

 condition to hold back water for the irrigation of lower Eg3^pt were 

 never considered seriously. 



The barrage is shown in the accompanying illustrations (Pis. XVI 

 and XVII). The Rosetta dam has 61 archways, while the Damietta 

 Branch has 71. The height of the archways is 41.82 feet from the floor 

 of the structure to the crown of the arch, or 32. S feet to the spring line 

 of the arches. The archways are 16.4 feet wide, and the piers support- 

 ing them are 6.56 feet thick. The original foundation of the dam was 

 simply a layer of concrete 111 feet wide and nearly 9 feet thick, cov- 

 ered by a stone and brick floor 1.64 feet thick. As work on each 

 section was undertaken, sheet piling was driven to keep the water 

 quiet while the concrete was being laid. The piers were constructed 

 on this floor. Locks were built at both ends of each dam and at the 

 head u-ates of the three canals. The flow of water through the sluice- 

 wa}^ was to have been regulated by gates of a new design, })ut they 

 never proved satisfactory, although a few still remained in the dam 

 until 1890. The gates now used close tightly, but a grating, through 

 which the water flows at all times, is beneath the sills on which the 

 gates rest. 



Since the English have been in control of Egypt repairs to the barrage 

 have been going on almost constantly. A new floor was laid, widening 

 the foundation 30 feet on the downstream and 78 feet on the upstream 

 side. It was thought better to widen rather than deepen the founda- 

 tion, because the material did not improve with depth. After this 

 work was completed new gates were put in the dam throughout. 

 These were made of wrought iron and provided with rollers, and they 

 slide in cast-iron grooves made fast to the piers. The gates are lifted 

 b}^ a traveling winch. One rail for supporting the car carrying the 

 lifting device was put on the upstream parapet of the dam. Brick 

 towers were l)uilt on the piers to support the second rail. These 

 towers, with the gates now employed, are shown in PI. XVII. 



Until 1896 the springs on the downstream side of the dam continued 

 to flow. Some water came through the gratings, but a large volume 

 flowed under the piers. In 1896 repairs were begun which will doubt- 

 less make the barrage an enduring structure. Through holes 5 inches 

 in diameter, drilled from top to bottom of the piers and lined with 

 iron pipes, clay or cement mortar was rammed. It was found in this 

 work that large cavities existed under the foundation, and as much as 

 40 barrels of cement were used for a single pier. The total cost of 



