metres per second in excess of the discharge at Assuân and 500 cubic metres per second in excess in November. The mean minimum discharge at Cairo is 500 cubic metres per second and is attained on the 15th of June; the river rises slowly through July and fairly quickly in August, and reaches its ordinary maximum on the 1st October when the basins are full and the discharge from the basins is just beginning. The ordinary maximum discharge at Cairo is about 7,600 cubic metres per second. Through October the Nile at Cairo is practically stationary, and falls rapidly in November. North of Cairo are the heads of the perennial canals which irrigate the Delta proper. The canals, with their feeders lower down, discharge 1,200 cubic metres per second, and the ordinary maximum flood at Cairo of 7,600 cubic metres per second is reduced by this amount between Cairo and the sea. Of the 6,400 cubic metres per second which remain, 4,100 cubic metres per second find their way to the sea down the Rosetta branch, and 2,300 cubic metres per second down the Damietta branch. During extraordinary floods the Damietta branch has discharged 4,300 cubic metres per second and the Rosetta branch 7,000 cubic metres per second. 25. =The Nile in low supply.=--We have so far considered the Nile in flood, it now remains to quickly dispose of the low supply. After reaching its maximum, the Atbara, which is a torrential river, falls more rapidly than others, and by the end of September has practically disappeared; after the middle of September the Blue Nile falls quickly, while the White Nile with its large basin, gentle flow and numerous reservoirs, falls very deliberately. The mean minimum discharge of the White Nile at Gondokoro in an ordinary year, at the time of low supply, is 600 cubic metres per second. Of the Sobat river it is 100 cubic metres per second. By the time the water reaches Khartoum it is reduced to 450 cubic metres per second. The mean low supply of the Blue Nile is 200 cubic metres per second, giving a mean low supply to the Nile at Khartoum of 650 cubic metres per second. The Atbara supplies nothing. Between Khartoum and Assuân there is a further loss of 60 cubic metres per second, and the mean low supply delivered at Assuân is 590 cubic metres per second. In very bad years the discharge at Assuân has fallen to 400 cubic metres per second.