After leaving the Albert Nyanza, the White Nile (or as it is there called the Bahr El Jebel) flows for 110 miles in a deep broad arm, with scarcely any velocity or slope, past Wadelai and Dufile to Nimule, and then, after a short and troubled course, between high mountain ranges, tosses over the Fola Rapids in a channel only 50 yards broad. From here it continues in a torrent to about Rejaf. Here the river is 7 feet deep at low Nile and 15 feet at flood time, discharging between 18,000 to 60,000 cubic feet per second. The regulating effects of the great lakes are well felt here. It is here at its lowest in winter; begins to rise about 15th April, with a minimum about the end of August. From Rejaf to Bor, 112 miles, the river is mainly in one channel with a rapid fall. From Bor to the junction with Lake No, 384 miles, the river meanders along in numerous marshy channels with a very gentle slope. The main channel always used is known as the Bahr El Jebel. In this reach are the dams of living vegetation, known as the “Sudd” (for description _see_ Appendix B). On one stretch the true channel is still blocked with sudd, and a “false” channel, a little to the westwards, has to be used for about 20 miles. [Sidenote: Lake No.] At the junction of the Bahr El Ghazal and the Nile in north lat. 9° 29′ is Lake No, or Moghren El Buhur,[20] a shallow expanse of water surrounded on all sides by reedy marsh and varying in size according to season, but in summer probably about 60 square miles. It forms a reservoir for the sluggish streams that drain the extensive plateau forming the water-shed between the Nile and Congo. In summer the lake and its swampy surroundings act as an evaporating basin, and the loss of water is consequently considerable. The waters here also become polluted with decaying green vegetable matter. The Bahr El Ghazal enters Lake No at its western extremity, and the Bahr El Jebel passes through its eastern end. The Bahr El Ghazal has a feeble discharge and has no effect at any time on the volume of the White Nile. In the stretch between Lake No and the Sobat, 81 miles, the current is slow and the channel occasionally blocked by sudd. [Sidenote: Sobat.] During flood, the Sobat has a discharge nearly equal to that of the Bahr El Jebel above the junction. In the spring the discharge from the Sobat is feeble, and the river is then unnavigable. The soil brought down by the Sobat is light and friable. [Sidenote: White Nile.] At the Sobat confluence the river changes its name[21] and now becomes the Bahr El Abiad or White Nile. From this point down to Omdurman, 530 miles, it receives no more perennial affluents, but several large khors join it on the east bank between Kodok and Renk—chief of which are Khor Adar and Khor Rau.