One of the earliest descriptions of the Nile between the fifth and tenth parallels of latitude is by Werne, who accompanied D’Arnaud’s expedition sent by Mehemet Ali in 1840-1841. The expedition found the channel of the White Nile and Albert Nile easily navigable between December and March. The Albert Nile between 7° and 9° N. lat. had apparently a mean width of 120 metres, depth of 5 metres, and velocity of about 60 centimetres per second, giving a discharge of some 400 cubic metres per second. In this first description of the river the fact that strikes one most forcibly is the omission of the Bahr Zeraf. Neither the inlet nor the outlet are mentioned, though the Sobat, the Gazelle, and numerous insignificant streams are minutely recorded. Practically the whole of the water was confined to one stream, and that a good one. The water level in winter was found to be some 50 centimetres below the general level of the berm, and about 60 centimetres above this level in flood. The swamps contained offensive and fetid water, which mixed with the waters of the rising flood and helped to pollute the stream on the first rise of the river. Between the river and the swamps in its southern reaches were numerous cuts and openings, some natural and some artificial, made by the aborigines for fishing purposes. While traversing the swamps, the waters of the river in flood lost their silt and became quite clear. On page 100 of Vol. II of Werne’s work there is this significant sentence: “The report that the natives below (i.e. in latitude 5° to 7°) had blocked the river to cut off our retreat, turned out to be unfounded.” From the above it will be noticed that the aborigines in 1840-1841 spoke of their ability to block the course of the river, while the training works in the side channels and spills for fishing purposes were described as solid works regulated by rows of strong stakes driven into the ground.