From the north-east spur of the table-land, out of vast lakes (Ukerewe), fed from the glaciers and snows of huge mountains lying under the equator, and passing through the lower lake Mwutan, flows the western arm of the Nile, the White Nile, Bahr-el-Abiad. After bursting through the terraces of the mountain, it reaches, at the foot, a woody morass, filled with thickets of tamarisks and sycamores, of bamboo and reeds and tall creepers, inhabited by the elephant and rhinoceros, the hippopotamus and the crocodile, the zebra and hyena, by antelopes and snakes. Then the stream passes into broad savannas, covered here and there with tropic forests, and while flowing through a mountainous district of moderate elevation, it unites with the eastern arm, the Blue Nile, Bahr-el-Azrak, which, rising further to the east out of the Abyssinian plateau, brings down a far smaller bulk of water from the Alpine glades of the snowy mountain Samen. Combined into one stream, these waters flow through a broad expanse of rock and desert, covered with conical stones of volcanic origin. The lines of hills running parallel to the terraces of the mountain rampart lie athwart the river; and through this barrier it breaks in numerous cataracts. Only in the depressions between them can the soil, refreshed with water, support vegetation. Finally, at Syene the Nile passes through the last cataract. Henceforward the structure of the mountains is changed. A fissure in the rock about 750 miles long opens on the Mediterranean; and through this the mighty river--at the last cataract it is 3,000 feet in breadth--can flow onward in undisturbed peace to the ocean.