However that may be, in 1890 the Government took the matter up, and charged Mr. W. Willcocks with the task of examining the river north of Wadi Halfa, reporting upon the best available site for the Dam, and preparing a design for it. After a careful survey, his plans were completed in 1894, and his design for a Reservoir at Assouan was then submitted to an International Committee of Engineers, consisting of Sir Benjamin Baker, M. Boulé, and Signor Torricelli. Mr. Willcocks’ plans were, with some modifications, accepted by a majority of the Commission, and to him belongs the honour of having designed the Dam. The selection of the Assouan site solved the first of the three difficulties. There is at this point an extensive outcrop of granite clean across the valley of the Nile, which it was thought would give sound rock everywhere at a very convenient level for the foundations of the Dam. Moreover, the trough of the river above the cataract and a long way south of it is exceptionally deep, and this makes it possible for a greater amount of water to be stored up behind the Dam. But the prime necessity was for a solid foundation. Elsewhere in Egypt the bed of the Nile is composed of shifting sands, on which it would have been impossible to build a Dam capable of holding up so great a head of water. Mr. Willcocks’ design solved the second difficulty, the problem of constructing a Dam strong enough for the purpose, and yet of avoiding the danger of filling up the Reservoir by too great accumulations of silt. The other great Dams in the world, as, for instance, that built by Sir Arthur Cotton on the Godavery River, in India, are solid throughout. They are planned so that the rising flood shall pass freely over the top of them. But the Assouan Dam is of a type previously unknown, and its success ought to stimulate perennial irrigation in many parts of the world where such projects have hitherto proved failures. Its principle is that even the highest flood shall pass, not over it, but through it. To this end it is pierced with 180 openings, which are like tunnels in the great mass of masonry. The openings are controlled by powerful sliding-gates worked from above. During the months of the flood every gate will be up, and the ‘red’ water, carrying all its heavy burden of silt, will pass through without impediment. Later in the year, about the end of November, when the flood has subsided and very much less matter is carried in suspension, the sluice-gates begin to be gradually closed, and by the end of February the Reservoir is full, without having affected the normal discharge of the river in any appreciable degree. From April to July the water thus stored up is let out by degrees for employment, according to the state of the river and the requirement of the crops. By the time the next flood begins to come down all the stored water will have passed out, and every sluice will be once more open to give free passage to the rising stream.