It is owing to the earliness of the Atbara high flood and the comparative lateness of the Nile high flood, that the ordinary maximum discharge of the Nile at Assuân is only 10,000 cubic metres per second. This is generally on the 5th September. When the monsoon is early the maximum at Assuân is reached before or on the 5th September; when the monsoon is late the maximum is reached about the 20th September. An early maximum at Assuân is generally followed by a low summer, while a late maximum is generally followed by a high summer supply. Only once has this rule been broken and that was in 1891 when there were two maxima, one on the 4th September and another on the 27th. In this year there must have been an extraordinary fall of rain in Abyssinia in September, for the flood of the 27th September was very muddy, while as a rule the river at Assuân is very muddy in August, less so in September, still less so in October and much less in November when the White Nile is the ruling factor in the supply of the river. If the September rains in Abyssinia are very heavy, an ordinary flood passes Assuân at the end of September and is disastrous for Egypt. This happened in 1878. Table 26 contains details of this flood, of the minimum flood year 1877 and the mean of the 20 years from 1873 to 1892. At Assuân the Nile enters Egypt, and it now remains to consider it in its last 1,200 kilometres. The mean minimum discharge at Assuân is 590 cubic metres per second and is reached about the end of May. The river rises slowly till about the 20th July and then rapidly through August, reaching its maximum about the 5th September, and then falling very slowly through October and November. The deep perennial irrigation canals take water all the year round, but the flood irrigation canals are closed with earthen banks till the 15th August, and are then all opened. These flood canals, of which there are some 45, are capable of discharging 2,000 cubic metres per second at the beginning of an ordinary year, 3,600 cubic metres per second in a maximum year, and have an immediate effect on the discharge of the Nile. The channel of the Nile itself and its numerous branches and arms consume a considerable quantity of water (the cubic contents of the trough of the Nile between Assuân and Cairo are 7,000,000,000 cubic metres), the direct irrigation from the Nile between Assuân and Cairo takes 50 cubic metres per second, 130 cubic metres per second are lost by evaporation off the Nile, and 400 cubic metres per second by absorption. Owing to all these different causes, there is the net result that, from August 15th to October 1st, the Nile is discharging 2,400 cubic metres per second less at Cairo than Assuân. During October and November the flood canals are closed, and the basins which have been filled in August and September discharge back into the Nile, and in October the Nile at Cairo is discharging 900 cubic