HE waters of the River Nile have been put into harness and made manageable for the benefit of Egypt. The mighty stream, swelling to a flood and overflowing once a year, was wont to bring fertility, in its own way, to the fields on either bank. But too soon these refreshing waters sank away, and too soon the short harvest was followed by a period of drought. It was a case of having more than enough water at one season and not enough at another, and it was plain to see that if the supply could only be regulated, the bare, parched plains of Egypt would have abundant crops more than once a year.

The best way to accomplish this would be to get control of the flood waters, and to keep some of them back in a huge reservoir, until the rain-regions, from which they came, began to stop supplies, and the river sank to its usual size. Then the gates of the reservoir could be opened, and the pent-up flood be allowed to gush forth again to refresh the thirsty fields.

In 1898 the performance of this task was undertaken by the engineering firm of John Aird & Co.,[1] at a cost of two million pounds, and in May of that year the scene of operations was chosen, four miles south of the town of Assuan. Here it was proposed to erect a dam, or barrier, right across the Nile. It would stand on the crest of a cataract and would be one mile and a quarter long. But as the river at flood-time carries down large quantities of rich deposit which is extremely beneficial to the soil on which it settles, it would never do to erect any obstruction to check this in its flow. Therefore this Nile dam must be a barrier capable of letting the river pass until its treasure was safely delivered in Egypt. Then the waters must be checked and the great reservoir filled. This could only be done by means of a number of sliding doors in the dam, which could be opened and closed at will.

The first examination of the cataract seemed to show that it flowed over sound, hard rock, and no difficulty was expected in finding a good, firm foundation. But when, to keep the water back while the work was in progress, sand-banks and temporary dams were built across the four channels through which the river flows to the cataract in the spring, it was found that the granite of the river-bed was 'rotten,' and in many places it was necessary to dig down thirty feet, before solid rock could be found. This was a sad surprise, for it seemed impossible to start building at such a depth, and carry the masonry to a sufficient height before the Nile in flood would come roaring down to Assuan. It was a race with time; and if the engineers failed to win, their temporary dams would be washed away, and would have to be built again next year before the great barrier could be gone on with. Already the Nile had more than once laughed at these temporary banks of sand and stone, and had broken through them and leapt upon its course as though jeering at human power. So persistent had been its attacks that the engineers almost despaired of finding anything heavy enough to hold its own in the opening which the water had made. At last two large railway waggons were filled with stones in wire cages, securely tied into the waggons with steel ropes. These, weighing altogether fifty tons, were pushed along a pair of rails on the top of the 'sudd' (or thick growth of weeds and flotsam) till they fell with a tremendous splash into the opening. Then the Nile was beaten. It could not move such a weight, and the masons worked on in peace—three hundred and fifty-three of them, night and day. Fortunately, too, the builders were encouraged by telegraphic reports received from stations farther up the river to the effect that the waters showed no signs of rising. The flood, in fact, proved unusually late that year, and by the time it came, the dam at Assuan was raised sufficiently high to be independent of the temporary 'sudds.' For three months work was suspended while the water roared through and over the stonework, but at the end of that time work progressed more rapidly than ever.

So cleverly had matters been arranged that no delay was caused by having to wait for materials. The granite was quarried in the neighbourhood, but was no more prompt in arriving at the scene of action than the coal and cement that came all the way from England. During the time of construction no less than twenty-eight thousand tons of coal were burned in the engine fires; and seventy-five thousand tons of cement were mixed to bind the granite blocks together, or to be formed into smooth slabs for facing the sluice-ways. In the long wall thus erected, which is seventy feet high in places (the bed of the river being so uneven) there are one hundred and eighty gateways or sluices, each nearly seven feet wide and twenty-three feet deep—except a few which are just half that depth. These openings are arranged on different levels, the bottom row being sixty feet below the surface of the water when the reservoir is full. They are all contained in a length of four thousand six hundred feet, the rest (one thousand eight hundred feet) of the dam being solid masonry. The sluice-ways are closed by iron gates which work vertically in grooves of steel, and can be raised or lowered from the top of the dam—a roadway sixteen feet wide. That these huge iron curtains may be lifted more easily, one hundred and thirty of them are fitted with rollers, and whatever the pressure of water, they rise and fall with great smoothness.

Five years were allowed for the accomplishment of this great task, but by diligence and promptness, John Aird & Co. were ready to pack up their tools and come away a whole year sooner than was expected. His Royal Highness the Duke of Connaught went to Assuan, in December, 1902, and declared the great dam fit to begin its important duties.

And this is how those duties are performed. Early in July each year, every sluice is opened to its widest, the iron doors being lifted as high as they will go. The Nile at that time is seen to be rapidly rising, and nothing must obstruct its passage. For five whole months it is allowed to rush in growing volume on its course. By that time, the rich deposit, of which we have spoken, has all passed through the sluices, and the time has arrived for checking the clearer and less turbulent water by which it is followed. The first gates are lowered early in December, being of course those in the lowest part of the dam. These are followed by fifty more on a higher level; and so on until all the sluices are carefully closed, with the exception of some which are left open for surplus water to pass through. The reservoir is not full until the end of February, and thus takes three months to collect its waters. But so vast is its extent, that the stoppage is said to affect the river one hundred and forty miles farther south. The water thus held back is not allowed to escape until May, when it is most wanted in the fields below the dam; and it is, of course, all gone by the beginning of July, when the sluices are gaping wide again to let the new floods pass. It need hardly be said that the order just described varies a great deal according to the moods of the river. The dam must be regulated to those changing moods, or the benefits it gives could not be relied upon. Thus from the fickle stream a constant blessing is drawn, and year after year, with the shifting seasons, those stately gates will rise and fall; the river channel will always have its water, so long as the gates last, and there will be corn in Egypt.