55 



10PULAR SCIENCE MONTHLY 



the multitudinous things incidental to the transformation of a remote 

 desert tract into a busy manufacturing town. Two months after sign- 

 ing the contract the permanent works were commenced, and before the 

 end of the year thousands of native laborers and hundreds of Italian 

 granite masons were hard at work. On February 12, 1899, the founda- 

 tion stone of the dam was laid by H.R.H. the Duke of Connaught. 

 Many plans were considered by the engineers and contractors for 

 putting in the foundations of the dam across the roaring cataract 

 channels, and it was finally decided to form temporary rubble dams 

 across three of the channels below the site of the great dam, so as to 

 break the force of the torrent and get a pond of comparatively still 

 water up stream to work in. Stones of from one ton to twelve tons in 



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b^ilsf 





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Fig. i. South Side of Dam, from West Bank. 



weight were tipped into the cataract, and this was persevered with 

 until finally a rubble mound appeared above the surface of the water. 

 The first channel was successfully closed on May 17, 1899, the depth 

 being about 30 feet and the velocity of current nearly fifteen miles an 

 hour. In the case of another channel, the closing had to be helped by 

 tipping railway wagons themselves, loaded with heavy stones, and 

 bound together with wire ropes, making a mass of about 50 tons, to 

 resist displacement by the torrent. 



These rubble dams were well tested when the high Nile ran over 

 them; and on work being resumed in November, after the fall of the 

 river, water-tight sandbag dams or sudds were made around the site 



