THE work entitled "The Albert N'yanza Great Basin of the Nile," published in 1866, has given an account of the equatorial lake system from which the Egyptian river derives its source. It has been determined by the joint explorations of Speke, Grant, and myself, that the rainfall of the equatorial districts supplies two vast lakes, the Victoria and the Albert, of sufficient volume to support the Nile throughout its entire course of thirty degrees of latitude. Thus the parent stream, fed by never-failing reservoirs, supplied by the ten months' rainfall of the equator, rolls steadily on its way through arid sands and burning deserts until it reaches the Delta of Lower Egypt.

It would at first sight appear that the discovery of the lake sources of the Nile had completely solved the mystery of ages, and that the fertility of Egypt depended upon the rainfall of the equator concentrated in the lakes Victoria and Albert; but the exploration of the Nile tributaries of Abyssinia divides the Nile system into two proportions, and unravels the entire mystery of the river, by assigning to each its due share in ministering to the prosperity of Egypt.

The lake sources of Central Africa support the life of Egypt, by supplying a stream, throughout all seasons, that has sufficient volume to support the exhaustion of evaporation and absorption; but this stream, if unaided, could never overflow its banks, and Egypt, thus deprived of the annual inundation, would simply exist, and cultivation would be confined to the close vicinity of the river.

The inundation, which by its annual deposit of mud has actually created the Delta of Lower Egypt, upon the overflow of which the fertility of Egypt depends, has an origin entirely separate from the lake-sources of Central Africa, and the supply of water is derived exclusively from Abyssinia.

The two grand affluents of Abyssinia are, the Blue Nile and the Atbara, which join the main stream respectively in N. lat. 15 degrees 30 minutes and 17 degrees 37 minutes. These rivers, although streams of extreme grandeur during the period of the Abyssinian rains, from the middle of June until September, are reduced during the dry months to utter insignificance; the Blue Nile becoming so shallow as to be unnavigable, and the Atbara perfectly dry. At that time the water supply of Abyssinia having ceased, Egypt depends solely upon the equatorial lakes and the affluents of the White Nile, until the rainy season shall again have flooded the two great Abyssinian arteries. That flood occurs suddenly about the 20th of June, and the grand rush of water pouring down the Blue Nile and the Atbara into the parent channel, inundates Lower Egypt, and is the cause of its extreme fertility.

Not only is the inundation the effect of the Abyssinian rains, but the deposit of mud that has formed the Delta, and which is annually precipitated by the rising waters, is also due to the Abyssinian streams, more especially to the river Atbara, which, known as the Bahr el Aswat (Black River), carries a larger proportion of soil than any other tributary of the Nile; therefore, to the Atbara, above all other rivers, must the wealth and fertility of Egypt be attributed.

It may thus be stated: The equatorial lakes FEED Egypt; but the Abyssinian rivers CAUSE THE INUNDATION.

This being a concise summary of the Nile system, I shall describe twelve months' exploration, during which I examined every individual river that is tributary to the Nile from Abyssinia, including the Atbara, Settite, Royan, Salaam, Angrab, Rahad, Dinder, and the Blue Nile. The interest attached to these portions of Africa differs entirely from that of the White Nile regions, as the whole of Upper Egypt and Abyssinia is capable of development, and is inhabited by races either Mohammedan or Christian; while Central Africa is peopled by a hopeless race of savages, for whom there is no prospect of civilization.

The exploration of the Nile tributaries of Abyssinia occupied the first twelve months of my journey towards the Nile sources. During this time, I had the opportunity of learning Arabic and of studying the character of the people; both necessary acquirements, which led to my ultimate success in reaching the "Albert N'yanza." As the readers of the work of that title are aware, I was accompanied throughout the entire journey by my wife, who, with extraordinary hardihood and devotion, shared every difficulty with which African travel is beset.