1895.] on The Nile. 409 



more than about three weeks later than an early rise. In average 

 years the height of the flood at Assouan is about 25J feet above the 

 minimum supply. If it rises 29 feet above this minimum, it means 

 peril to the whole of Egypt, and the irrigation engineer has a hard 

 time of it for two months. If the river only rises 20 feet above the 

 minimum, it means that whole tracts of the valley will never be sub- 

 merged. Such a poor flood has happened only once in modern times, 

 in 1877, and the result was more serious than the devastation caused 

 by the most violent excess. 



The mean flood-discharge at Cairo is about 280,000 cubic feet per 

 second, the maximum about 400,000. The mean lowest Nile is about 

 14,000 cubic feet per second at Cairo, but some years there is not 

 more than 10,000 cubic feet per second passing Cairo in June, and 

 within three months after this may have increased fortyfold. 



Until this century, the irrigation of Egypt only employed the 

 flood-water of the river, and it was this that made it the granary of 

 the world. No doubt rude machines for raising Nile water were used 

 at all seasons and from all times. But by these it was not possible 

 to irrigate on a large scale, and in reality they were only employed 

 for irrigating vegetables or gardens, or other small patches of land. 



It must not be thought that the water of the flooded river is ever 

 allowed to flow where it lists over the lands. The general slope of 

 the valley on each side is away from the river, a feature which the 

 Nile shares w r ith all Deltaic streams. Along each edge of the river, 

 and following its course, is an earthen embankment, high enough not 

 to be topped by the highest flood. In Upper Egypt, the valley of 

 which seldom exceeds six miles in width, a series of embankments 

 have been thrown up, abutting on their inner ends against those 

 along the river's edge, and on their outer ends on the ascending sides 

 of the valley. The whole country is thus divided into a series of 

 oblongs, surrounded by embankments on three sides, and by the slope 

 of the desert hills on the fourth. In Lower Egypt, where in ancient 

 days there were several branches of the river, this system was some- 

 what modified, but was in principle the same. These oblong areas 

 vary in extent from 60,000 to 3000 or 4000 acres, and the slope being 

 away from the river, it is easy to cut short, deep canals in the banks, 

 which fill as the flood rises, and carry the precious mud-charged 

 water into these great flats, or, as they are termed, basins of irriga- 

 tion. There the water remains for a month or more, some 3 or 4 feet 

 deep, depositing its mud, and then at the end of the floxl it may 

 either be run off direct into the receding river, or, more usually, 

 passed off through sluices from one basin to another, and ultimately 

 back into the river. In November the waters have passed off, and 

 wherever a man and a pair of bullocks can walk over the mud, and 

 scratch its surface with a wooden plough or even the branch of a 

 tree, wheat or barley is sown ; and so saturated is the soil that the 

 grain sprouts and ripens in April or May without a drop of rain or 

 any fresh irrigation. And a fine crop is reaped. One of our o;rcat 



