The object of the basins is to regulate the supply of the flood-water. Each series of basins has special feeder canals to lead into them. These are shallow, and have their bed about halfway between the high and low level of the Nile. They are therefore dry in the winter and summer, and only run during the flood. The heads of these canals, where they take off from the Nile, remain closed by dams or by masonry regulators till the silt-bearing flood is coming down in sufficient strength. Then about August 10 or 12 the canals are opened and the basins filled. The lowest basins in each series are filled first, then the next lowest, and so on. In a low flood, as in 1877, there is not enough muddy water to go round, and the upper basins get no water at all; such lands are called ‘sharaki,’ and are exempt from taxation. For forty days the flood-water stands on the land, thoroughly soaking it and washing it, and at the same time depositing its fertilizing silt. At the end of that time, through the escape at the lower end of the series, the water is discharged back again into the Nile. But if the flood is a very high one or very slow in abating, the date at which the water can be discharged and the basins dried has to be postponed. Fortunately, this seldom happens; but when it does it has a doubly bad effect. The oversoaking is said to engender worms, and also the ripening of the crops is postponed to an unfavourable season of the year. Against this particular evil there is no remedy, but since the British occupation a great deal has been done to improve the system of basin irrigation, and prevent a large amount of sharaki even in years of low Nile. These measures consist in arrangements for distributing the ‘red’ water more evenly over the whole system, and not allowing the lower basins only to receive the full benefit, while the higher merely receive ‘white’ water—_i.e._, water which has already deposited its silt. Further, since any water is better than none, the systems of basins have been so managed, where possible, that the water from an upper system can be drained into a lower one, and thus make up deficiencies, though with water of an inferior quality. More attention has also been paid to the angle at which the feeder canals take off from the Nile, and the slope on which they are laid, so as to provide as much ‘red’ water as possible, while diminishing the amount of silting up. The result of this work is seen in the diminution of the sharaki lands year by year. In 1877 these amounted to nearly 1,000,000 acres, a loss of £1,000,000 in land-tax. During the next ten years the average was 45,000 acres, an annual loss of some £40,000. In 1888 the loss was £300,000, and the Egyptian Government expended £800,000 in remedial works, which have had an extraordinary effect. In 1899, when the Nile was exceptionally low, the sharaki lands amounted to 264,000 acres only, as against nearly 1,000,000 in 1877.