At Lake No 1/87500 flood season. At „ 1/54000 dry season. White Nile— Above Sobat 1/20000 dry season. At Dueim 1/100000 when Blue Nile has fallen and the While Nile is at its maximum. At Dueim 1/50000 dry season. Blue Nile At Khartoum 1/11200 flood season. (See also footnote on p. 111, giving a short table of comparative discharges.) (iv.)—NAVIGABILITY (UP STREAM). Between Halfa and Khartoum (880 miles) the river may be said to be navigable throughout at high Nile. Details are given below as to the various cataracts to be encountered, but it may be broadly said that, although difficult, it is not impossible to get boats and steamers through in the time of the flood. At low Nile most, if not all, of the cataracts are unnavigable. Before the Nile Expedition of 1884-85 steamers and boats were taken over the 2nd cataract. During the expedition both were taken over the 3rd cataract and intervening rapids, and boats (whalers) successfully surmounted the 4th cataract. In 1897 gunboats and other steamers were hauled over the latter place, and the rocks of the 5th and 6th cataracts have never, when there was enough water, offered serious resistance to the passage of boats or steamers. From Khartoum to Gondokoro, practically 1,100 miles, the only obstacles to navigation at any time of the year are:— 1. The Abu Zeid Ford (occasionally only), and the Azalet or Dankul Rocks near Jebelein, _vide_ p. 59. 2. Scarcity of fuel. 3. The sudd. 4. Sand-banks. 2. FUEL.—One of the great economic questions of the Sudan which would give rise to anxiety were not the Nile-Red Sea Railway already in course of construction is the future supply of fuel. Imported coal now costs £E.4 to £E.6 per ton, and petroleum £6 to £E.11·500 per ton at Khartoum. Though a bed of lignitic coal has been discovered at Dongola, no other coal, nor even lignite, has so far been located within our boundaries. Wood therefore, is and will for some time remain the chief source of fuel supply. The large demand which arose with the development of Khartoum has caused the destruction of forest belts along the White and Blue Niles to a considerable distance from Khartoum, and although the Forest Department has now control of the fellings, the enormous demand is making inroads into the forests from which subsequent fires preclude recovery.