are under 5,000 acres, the cost will be nearly double this. The annual cost of maintenance is £·10 per acre; while the lands themselves are rented at £3 per acre. In well irrigated basins no manures are needed, and alternate crops of cereals and legumins have been reaped for centuries without the land having been exhausted in any way whatever. Where the subsoil water is good and double cropping resorted to, then manures have to be applied. 29. =Perennial Irrigation.=--The foundation-stone of the conversion of the whole of Egypt from basin to perennial irrigation was laid by Mehemet Ali in 1833, when he began the construction of the Barrages across the Nile branches north of Cairo. These weirs were intended to raise the summer level of the Nile by 3 metres. As the ordinary summer level of the Nile was 1.50 metres above its bed, the weirs were expected to raise it 4.50 metres above the Nile bed. The old basin canals had to be considerably deepened to take in the summer supplies; while in other parts new perennial canals were dug. Perennial irrigation requires canals capable of discharging 1 cubic metre per second per 3500 acres, as against 700 acres for basin irrigation. Some of the perennial canals are very capacious. The two largest discharge 700 and 450 cubic metres per second respectively. There are no artificial canals in the world like them. All the canals are liberally provided with regulators and locks. The energies of the Irrigation Department during the last ten years have been chiefly directed to the provision of sufficient drains to meet that over-saturation of the soil, which all but the best regulated perennial irrigation invariably entails. After many years’ experience in India and Egypt, we are convinced that the construction of drains and escapes should precede, and not follow the canals. It seems fatuous for engineers to be always over-saturating and half-ruining tens of thousands of acres of low-lying lands, during the improvement of hundreds of thousands of acres of high-lying lands, when it would be perfectly easy, with a little foresight, to secure all the advantages without piling up disadvantages. The drains have generally one-third the capacity of the canals. Dry crops require 1 cubic metre per second per 3500 acres; and rice requires the same per 2000 acres. The drains in dry-cropped lands provide for 1 cubic metre per second per 10,000 acres, and in rice lands 1 cubic metre per second per 6000 acres. [Illustration: PLATE XIX. PERENNIAL CANAL SYSTEM OF LOWER EGYPT Lith. Sur. Dep. Cairo.] While basin irrigation is followed by the winter crops of wheat, beans, clover, barley, flax, lentils, vetches and onions, perennial irrigation allows of all the above winter crops and in addition the summer crops of cotton, sugar-cane, oilseeds, gardens and orchards. It will readily be understood that all this double cropping necessitates a very free use of manures.