560 



POPULAR SCIENCE MONTHLY 



dam. A triple line of railway, and numerous trucks and locomotives, 

 were provided to convey the materials from quarries and stores to every 

 part of the work. The maximum number of men employed was 11,000, 

 of whom 1,000 were European masons and other skilled men (Figs. 3, 

 4 and 5). 



Mr. Wilfred Stokes, chief engineer and managing director of 

 Messrs. Eansomes and Eapier, was responsible for the detailed design- 

 ing and manufacture of the sluices and lock-gates; 140 of the sluices 

 are 23 feet high by 6 feet 6 inches wide, and 40 of them half that 

 height; 130 of the sluices are on the 'Stoney' principle, with rollers, 

 and the remainder move on sliding surfaces. The larger of the Stoney 



sluices weigh 14 tons, and are 

 capable of being moved by hand 

 under a head of water producing 

 a pressure of 450 tons against the 

 sluice. 



There are five lock-gates, 32 

 feet wide, and varying in height 

 up to 60 feet. They are of an 

 entirely different type to ordinary 

 folding lock-gates, being hung 

 from the top on rollers, and mov- 

 ing like a sliding coach-house 

 door. This arrangement was 

 adopted for safety, as 1,000 mil- 

 lion tons of water are stored up 

 above the lock-gates, and each of 

 the two upper gates is made 

 strong enough to hold up the 

 water, assuming the four other 

 gates were destroyed (Fig. 6). 

 When the river is rising, the sluices will all be open, and the red 

 water will pass freely through, without depositing the fertilizing silt. 

 After the flood, when the water has become clear, and the discharge 

 of the Nile has fallen to about 2,000 tons per second, the gates with- 

 out rollers will be closed, and then some of those with rolllers; so 

 that between December and March the reservoir will be gradually 

 filled. The reopening of the sluices will take place between May and 

 July, according to the state of the Nile and the requirements of the 

 crops. 



Between December and May, when the reservoir is full, the island 

 of Philse will in places be slightly flooded. As the temples are founded 

 partly on loose silt and sand, the saturation of the hitherto dry soil 

 would cause settlement, and no doubt injury to the ruins. To obviate 

 this risk, all the important parts, including the well-known Kiosk, or 



Fig. 6. Navigation Canal. First Lock- 

 gate from North. 



