Page:Africa by Élisée Reclus, Volume 1.djvu/92

 chief commercial outlet of all Upper Egypt. Over fifty years ago the English already sank wells at intervals along this gorge, with the view of utilising it for the overland route to India.

After flowing westwards below the great bend of Keneh, the Nile trends northwest and north; but in this part of its course it bifurcates, one arm branching off and flowing parallel with it on the west side at a mean distance of seven miles. This is the Bahr-Yusef, or " River of Joseph," so called in memory of Pharaoh's minister mentioned in the Jewish traditions, or rather of a certain Joseph, minister of the Fatimites in the twelfth century. But it does not appear to have been excavated by the hand of man, although it has been frequently embanked, deflected, and directed into lateral channels, like all the running waters of the valley. Recently the point of derivation has been displaced, and the canal named Ibrahimieh has been raised to the level of the high banks in order more easily to regulate the discharge of the flood waters. In the part where it has not been canalised the Bahr-Yusef, skirted along its left bank by the dunes drifting before the desert wind, is a winding stream like the Nile, having, like it, its islands, sand- banks, eroded cliffs, and network of watercourses and false rivers. Its mean breadth is about 330 feet, but through it very little of the Nile waters are distributed. Feeders from the main stream, in traversing the intermediate plain, replenish the River of Joseph at intervals, thus making good the losses caused by evaporation. This phenomenon, of two parallel streams in one and the same valley, one the main stream discharging nearly the whole liquid mass, the other a small current winding through an ancient river bed, recurs in nearly all those valleys whose hydrographic system has not yet been completely changed by canalisation and drainage works. Several rivers skirted by embankments have also their Bahr-Yusef, like the Nile. Such in France is the Loire, skirted by the Cisse, by the waters derived from the Cher, the Indre, and the Vienne ; lastly by the river Authion, with its numerous ramifications.

About 300 miles from the point of bifurcation, the Bahr-Yusef penetrates into a lateral valley, where it ramifies in its turn. The eastern branch, which continues the river properly so-called, penetrates north-eastwards through a breach in the Libyan range, beyond which it rejoins the Nile above its delta. But the western branch trends abruptly north-westwards to a rocky gorge, at the entrance of which its course is regulated by a three-arched bridge built in the thirteenth century, and furnished with flood-gates allowing the stream to pass, or diverting it to the surrounding plains. Beyond the barrage the canal winds through a ravine about 6 miles long in the Libyan range, at the outlet of which it suddenly debouches in a valley of amphitheatral form, and nearly 110 miles in circumference. This is the Fayum depression, which is watered by an intricate system of canals, rills, and rivulets, ramifying like the veins and arteries in a living organism. At its lowest point this hill-encircled basin is estimated at from 86 to 116 feet