COMPLETION OF ASSUAN DAM.
The Great Engineering Work a Success.
On February 12, 1899, the Duke of Connaught, brother of the King of England, laid the foundation stone of the great Assuan dam across the Nile, and on December 10, 1902, the Duchess of Connaught, in presence of her husband, laid the last stone after the Khedive of Egypt had turned a key which set the electrical machinery in motion and allowed a great body of water to rush through the 180 opened sluice gates and which had been closed in the mile and a quarter wall of masonry at the beginning of this month for the storage of water till the end of March. The works comprehend a dam and navigation channel at Assuan, a barrage and lock at Assiut, and a regulator and lock at the head of the Ibrahimet canal at the latter place. The dam is built across the first rapids of the first cataract to the north of the island of Philae, whose ancient temples are not entirely submerged. The contract for the works was let to John Aird & Co. (the head of the firm. Sir John Aird, has since been knighted) for $10,000,000, repayable in sixty half yearly instalments of $396,065, beginning on July 1, 1903—the date fixed for the completion of the works. Owing, however, to the bad rock met with in the excavation of the foundations a large extra expenditure has been caused for masonry. This amounts to $10,020,000—the excess being advanced by the government, to be refunded by the Public Debt Commission in two equal yearly payments.
The dam is to hold up water to 106 metres (a metre equals a little over three feet three inches) above mean sea level; the greatest head on the dam will be twenty metres, the lowest level on the downstream side being eighty-six metres. The storage capacity is estimated at 1,065,000,000 cubic metres of water (a cubic metre equals 26.47 gallons). The reservoir will be filled between December and March, after the flood has passed, and will be discharged during May, June, and July. There are 140 under sluices, fourteen square metres in area, and forty upper sluices, seven square metres in area. In flood the sluices will be fully open, so as not to lessen appreciable the velocity of the river, and to avoid the deposit of silt. After the flood, when the water is clear, the sluices will be gradually closed and the reservoir filled. In an average year it should be filled by March 1, when only the upper sluices will be opened, the others, one after the other, till July, when all will be fully opend, thus regulating the fertility of the Nile valley for fifty miles below Assuan. The sluices are closed by steel gates and are lined with heavy granite ashlar or cast iron. The dam is straight from end to end, and its length is about two thousand metres. Its width at the top is seven metres, and at the deepest part twenty-five metres. The height from the lowest part of the foundation to the top is forty metres. The interior masonry is rubble granite in 4 to 1 cement mortar, the interior casing is of square rockfaced granite in 2 to 4 cement mortar.
The navigation canal on the left flank of the dam, opening up a route throughout the year to Wady Haifa, and through which all the water traffic of the Nile will pass (the cataract passage is now abolished), is about 2.000 metres long. There are four locks, each seventy metres long and forty-nine and one-half wide, with gates graduating in height from nineteen down to eleven metres.
The number of workmen employed reached at one time nearly 11,000, of whom over 900 were Europeans —largely Italian stonemasons. Over 3,000 tons of masonry were sometimes completed in a day, and as much as 45,000 cubic metres of masonry were laid in one month just before the flood came down. Many unforeseen difficulties had to be overcome.