THE COURSE OF THE NH^E 13

utilitarian importance, consists of the territory

drained by the Bahr-el-Ghazal and its tributaries to

the east of the Great Divide, from the western

side of which many rivers flow into the Congo, and

eventually into the Atlantic Ocean.

The general trend of the Nile to the north-

ward is broken in one important and one minor

instance.

Entering the Sudan at a point 4 degrees above the

Equator it follows a rapid but tortuous course into

the regions of swamp which characterize its most

southerly section above the junction with the Bahr-

el-Ghazal (this river being its first and only tributary

on the west bank); it then takes a severe turn to

the east, until once more deflected to its original

direction by the flood with which the Sobat opposes

it. North of Khartoum, in the Dongola province,

it presents a remarkable divergence from its general

course, assuming the form of the figure S on its side,

the middle stretch actually flowing south-west for

nearly 200 miles. During the whole of its course,

the Nile only receives four tributaries of any im-

portance—those on the east bank three in number,

being the Atbara, north of Khartoum ; the Blue

Nile, on which Khartoum is situated ; and the

Sobat, far south, all taking their rise in Abyssinia.

Broadly speaking, the country might be divided

into four sections : the desert of the north, the dry

but inhabitable country of the west, the cultivatable

areas of the centre and east, and the marshy, tropical

regions of the south. But this classification, on