Cairo to Kisumu

by Frank G. Carpenter

For thousands of years these rivers have been pouring down through this Nile valley; but whenever the rains have been scanty in the highlands of Abyssinia and in Central Africa the main stream has not been high enough to reach the whole country. Most of the lands could be inundated only once a year, and if the Nile was especially low some could have no water at all. By the present system Egypt has water all the year round, and enough to make it produce two or three crops every twelve months.

I have been much interested in the irrigation works of the past. The whole of the Nile valley above Cairo is cut up into a series of basins. For six hundred or seven hundred miles north of this point the valley slopes very gradually and, in order to save the water, dikes have been made across it and embankments run parallel with the river, turning the whole country into a series of basin-like terraces, each containing from five thousand to fifteen thousand acres. These basins, which are often subdivided, are so connected that the water flows from one to the other until it finally passes out of the lower basin back into the Nile. When the floods come, the lowest basins are filled first and then those higher up, until at last all have become great ponds and Egypt is one vast inland sea cut up by the embankments and islands upon which the villages stand.

There are many such systems of basins in Upper Egypt, some large and some small. There are also basins higher up and closer to the river which are filled with sakiebs or shadoofs. When I tell you that the fall of this valley from here to Cairo is only seven inches to the mile you will see how carefully these basins must be graduated in order to take advantage of the flow of the river. They have to be so constructed that the water can be drained off as rapidly as it is let on. As I have already said, the Abyssinian mud contains a great quantity of salts, and it is just as bad to have too much of it as too little. If the land is over-watered the salts dissolve from the soil, the over-soaked land becomes wormy, and the crops are often sown too late. The red water, or that containing the silt, is allowed to stand just about forty days. During this time it drops a great deal of sediment and furnishes enough moisture for the crops.

But the Aswan Dam has so regulated the river flow that the Egyptian farmer is far less at the mercy of low Niles or high Niles than in the past. The dam is one of the wonders of modern Egypt. It is in full sight of me as I sit here on the left bank of the Nile, with the desert at my back. It looks like a great stone viaduct crossing the rocky bed of the river, joining the stony hills which wall the Nile on both sides, and holding back a portion of its mighty waters. It is a huge granite barrier a mile and a quarter long. There is now a roadway guarded by walls on its top, and there is a miniature railway, the cars of which are pushed by men from one end to the other. The dam serves as a bridge as well, and donkeys, camels, and men are allowed to pass over it from bank to bank. I crossed on the car at a cost of twenty-five cents, my motive power being two Arab boys who trotted behind.

As I came over, I stopped from time to time to examine the construction. The dam is made of big blocks of red granite as fine as that of any tombstone in the United States. They are beautifully cut, and fitted as closely as the walls of a palace. On the upper side or south face the wall is perpendicular, forming a straight up-and-down barrier against the waters of the Nile. I climbed down a ladder on that side at one place almost to the river, and could see that the blocks are fitted so closely that the cement does not show. The masonry seems almost one solid stone throughout, with the exception of where the great sluices are cut, to allow the river to flow through at the times of the flood, and as the floods subside to shut back the waters to form the reservoir for the dry season.

There are one hundred and eighty of these sluice gates in the dam, each of which has steel doors that can be raised or lowered to allow the whole river to flow through or to hold back as much or as little as the engineers will. The dam is thus a great stone wall pierced by these gates.

The Nile never flows over the top of the dam, but always through the gates and the canal at one side. When the gates are closed during the dry season, enough water is held back by this structure of steel and granite to form a lake over one hundred miles long, and this is let out as needed to supplement the ordinary flow of the river and give the crops plenty of water all summer through. There is water enough in the reservoir to give all the families of the United States all they could use for four or five months, and enough to supply Great Britain and Ireland the entire year.

The weight of this water is stupendous and its force inconceivable. Nevertheless, during the floods fully as much runs through the dam every day as the whole supply kept back during the dry season; and the structure had to be made so that it would retain this huge lake and at flood time let a lake equal to it pass through.

Talk about the Pyramids! The Aswan Dam is far more wonderful than they are. The Pyramid of Cheops required one hundred thousand men and over twenty years in its building. The Aswan Dam was constructed by about eleven thousand men in four years. The Pyramid of Cheops was made by forced labour and impoverished the people. The Aswan Dam cost about twelve million dollars and the men who worked upon it were better paid than any others who had ever laboured in the valley of the Nile. Moreover, the dam has meant prosperity for Egypt. It has added to it more than one million five hundred thousand acres of tillable land and has increased the value of its crops by over thirteen million dollars per annum. It has more than paid for its cost every year. Since it has been built the yearly tax revenues have gained by two million dollars, and the lands owned by the government have become worth five million dollars more.

The dam is also more wonderful than the Pyramids in its construction. Old Cheops is built on the edge of the desert on a solid stone platform, and is little more than the piling of one stone upon another. For the Aswan Dam a trench a hundred feet wide and a hundred feet deep had to be excavated in the granite rock. This was bedded with concreted rubble to form the substructure upon which the masonry was raised. The dam itself contains more than a million tons of granite and about fifteen thousand tons of steel, and the calculations of the engineers are so exact that they know just how much every ounce of stone and steel will hold back.