55 POPULAR SCIENCE MONTHLY. 



THE NILE DAMS AND EESEEVOIE.* 



BY SIR BENJAMIN BAKER, F.R.S., 

 PAST PRESIDENT INSTITUTION OF CIVIL ENGINEERS. 



THE Nile Keservoir at Aswan will contain over 1,000 million tons 

 of water. This statement will probably convey little meaning 

 to most people; and in truth the quantity may be made to appear either 

 small or large at will by a judicious selection of illustrations. Thus 

 the absolute insignificance to Egypt of 1,000 million tons of water in 

 a reservoir, as compared with a reasonable rainfall, will be apparent 

 at once when it is considered that the annual rainfall on the area in- 

 cluded within the four-mile cab radius from Charing Cross is about 100 

 million tons, and that the rainfall on London and its suburbs within a 

 thirteen-mile radius would, therefore, about suffice to fill the Nile 

 Eeservoir. On the other hand, we may, by choosing other illustrations, 

 restore the Nile Eeservoir to the dignity of its just position of one of 

 the greatest engineering works of the clay. Thus the question of the 

 water supply of London, and its prospective population of 11 14 

 millions, has been prominently before the public for some years; and 

 many will remember what was termed the colossal project of our mem- 

 ber, Sir Alexander Binnie, late Engineeer of the London County Coun- 

 cil, for constructing reservoirs in every reasonably available valley in 

 Wales, to store up water for London, and to supply compensation 

 water to the Welsh rivers affected thereby. Well, the united contents 

 of the whole of those reservoirs would be less than half that of the 

 great Nile Eeservoir. Again, the Nile Eeservoir would hold more than 

 enough water for one year's full domestic supply to every city, town 

 and village in the United Kingdom with its 42 million inhabitants. 

 But possibly the best way of giving an idea of the magnitude of the 

 work, and its utility to cultivation in a thirsty land, is by consider- 

 ing the volume of the water issuing from the reservoir during the three 

 or four summer months, when scarcity of supply prevails in the river 

 ?nd the needs of the cultivators are greatest. At that time the flow 

 from the reservoir will be equivalent to a river double the size of the 

 Thames in mean annual flood condition. It will be recognized at once 

 that a good many buckets would have to be set at work to bale out a 

 river like that, and yet the scarcity of water in the Nile itself, and in 

 the canals, during the months of April, May and June, is such that 

 even dipping the water out of the channels in buckets has to be con- 



* Address given before the Royal Institution of Great Britain. 



