TRANSACTIONS OK SECTION G. 763 



river, and thus enable land to be irrigated which would otherwiae receive either 

 no water, or an insutiicient supply. The situation chosen for the dam was the 

 head of the Assuan cataract. There were various reasons for the choice : there was 

 a wide section of the river, the waterway being about seven-eighths of a mile, thus 

 permitting the construction of sufficient sluices at difterent levels to discharge the 

 whole volume of the Nile in flood without weakening the dam by placing them too 

 close together ; the height of the dam would be moderate ; the site chosen seemed 

 to promise good rock foundation throughout, and there were several natural 

 channels when the water was low, each of which could be dealt with separately 

 if desired. 



Arrangements had to be made to house and feed a population of 15,000 ; offices, 

 workshops, a hospital, and other temporary buildings had to be erected, and a line 

 of railway about 3 miles in length had to be constructed to connect the railway 

 from Luxor to Assuan with the works at the dam. This preliminary work was 

 carried out in 1898, and on February 12, 1899, H.Ii.H. the Duke of Connaught 

 laid the foundation-stone of the dam. 



To enclose the site of the permanent masonry dam, and to render it dry for the 

 purpose of excavation and laying the masonry, temporary dams, known in Egypt 

 as ' sudds,' had to be formed both above and below the site of the permanent dam. 

 At low Nile the river at the Assuan cataract divides itself into five channels, and 

 this work was done in five sections. The down stream ' sudds ' were first made, 

 and consisted of stones. After the rush of water had been thus stopped, the up- 

 stream ' sudds ' were formed of bags of sand. 



It was found that the rock on the site of the dam was decomposed. The 

 importance of a solid rock foundation was paramount, and to obtain it the 

 excavation had to be carried down to a considerable depth, necessitating the 

 removal of double the amount of material which had been contracted for, and the 

 construction of nearly one and a half times the quantity of masonry that had been 

 anticipated. The masonry, consisting of local granite set in Portland cement mortar, 

 was commenced in May 1900, was carried on vigorously during two working 

 seasons in which the Nile was abnormally low, and was finished in June 1902, 

 less than 3J years i'fter the first stone was laid, and one year before the 

 expiration ot the contract time. The dam is nearly 1:^ miles in length, and the 

 diflerence between the surface of the water on the up-stream side and that on 

 down-stream side is 65^ feet when the reservoir is full. The masonry is pierced 

 by 180 sluices, of which 140 are 23 feet high by 6 feet 6f inches wide, and 40 are 

 11 feet 6 inches high by 6 feet 6f inches wide. 



The construction of the dam having closed the river to navigation, provision 

 for the passage of vessels was made by means of a canal formed on the west 

 bank of the Nile and having a succession of four locks. 



The capacity of the Nile reservoir when filled to the top water height of 

 348 feet above mean sea level is about 37,000 million cubic feet, a quantity which 

 might have been greatly increased had not the desire to preserve the Temple of 

 Philse prevented the raising of the water to the level originally proposed. Even 

 now many portions of the temple or its adjacent buildings are partially submerged. 

 It is anticipated that by allowing the whole volume of the Nile to pass through 

 the sluices when most laden with mud during floods, the silting up of the 

 reservoir to any considerable extent will be prevented. The cost of the works was 

 nearly 2,450,000/. or about 10/. per million gallons of water impounded. 



The original surveys and designs for the works were prepared by Mr. Willcocks 

 (now Sir William Willcocks, K.C.M.G.), under the instructions of Lord Cromer 

 and Sir William Garstin, Sir Benjamin Baker, K.C.B., K.C.M.G., F.R.S., Past 

 President Inst.C.E., being the consulting engineer. On the retirement of Mr. 

 Fitzmaurice, he was succeeded by Mr. C. R. May, M.lnst.O.E., as engineer in 

 charge. The work was carried out by Messrs. John Aird & Co., as contractors, 

 Mr. John A. C. Blue, Assoc.M.Inst.C.E., acting as their agent. 



All concerned in the inception and execution of this great undertaking are to 

 be congratulated on its successful and speedy completion, in the face of the many 

 difficulties which were encountered and overcome. 



