UNWRITTEN HISTORY. 3 2 7 



Nubia, the granitic masses of the desert on the eastern or Arabian side 

 spread suddenly to the westward, and come to the surface in place of 

 the sandstones. In the course of the six or seven miles between As- 

 souan and Philre the bed of the river rises sixteen feet,* forming a de- 

 clivity, down which the stream rushes in a rapid, known as the First 

 Cataract. The alluvial soil has almost vanished, and the river flows 

 amid a confused heap of granite blocks, with black and polished sur- 

 faces. For some eight degrees of latitude farther south, the granite 

 and sandstone plateau which rises so suddenly at Assouan extends 

 through Nubia, increasing in elevation, until at the foot of the second 

 cataract ("Wady Haifa) the level of low Nile reaches 392 feet ; at the 

 third cataract, 659 feet ; at the fourth, 745 feet. Where the White 

 and Blue Niles join, just below Khartoum, in 16 north, the river is 

 1,212 feet above the sea, or more than 900 feet above its height at As- 

 souan. 



Throughout the whole of this course the Nile receives but one afflu- 

 ent, the Atbara, which carries the drainage of a part of Abyssinia into 

 it in about 18 north. And, as this solitary tributary is wholly in- 

 adequate to make good the loss which the main stream suffers by 

 evaporation and percolation, on its course through thirteen degrees of 

 one of the hottest and driest climates in the world, the Nile presents 

 the singular spectacle of a river the volume of water in which is con- 

 spicuously less than that poured into it by its feeders. 



The Blue and the White Niles, which unite to form the main stream 

 close to Khartoum, are in fact very large rivers, each of which drains 

 an immense area abundantly supplied with water. The one receives 

 the overflow of the great equatorial Nyanza lakes and the drainage of 

 the vast swampy region of the Soudan to the north of them, in which 

 the heavy intertropical summer rains accumulate. The other is fed 

 not only by such rains, but by the snows among the mountain-tops of 

 Abyssinia, which melt as the sun advances to the northern tropic. 



The height of the water in the Nilometer at Cairo is contingent 

 upon the meteorological conditions of a region more than a thousand 

 miles off ; and the question whether Egypt shall have a year of famine 

 or a year of plenty hangs upon the rainfall in Abyssinia and equatorial 

 Africa. It is as if the prosperity of the agricultural interest in Berk- 

 shire depended on the state of the weather in Morocco. 



The general course of the Nile is so directly north and south that 

 the thirtieth parallel of east longitude, which traverses the Albert 

 Nyanza Lake on the equator, passes close to the Rosetta mouth at its 

 outfall. The Albert Nyanza is 2,500 feet above the sea ; and, since 

 the length of the part of the great circle inclosed between the points 



* The heights of points in the course of the Nile, given in books, are widely discrepant 

 and usually very inaccurate. I am indebted to the eminent civil engineer, Mr. John 

 Fowler, for this and subsequent precise determinations. The height of low Nile above 

 the sea is 303 feet at Assouan, 319 feet at Philse. 



