Hence to Khartoum, as stated above, the river is navigable for nearly the entire year, vide [Chap. X.]
Rainy season.The rainy season in the Bayuda Desert is uncertain, as this is the extreme northern range of the tropical monsoon; there may be showers in May, but the true rains fall in June, July, or August. Some years may pass without any at all, and then a perfect deluge floods the country and refills the pools and wells.
Water.The conformation of the Jebel Gilif is such, that notwithstanding the large amount of water running off during the rains, a considerable quantity is stored at high levels, gradually finding its way into the sand-filled wadis, through permeable granite augites and diorites, of which Jebel Gilif is composed.
These wadis are crossed at intervals by spurs of trap rock, that serve the double purpose of keeping up the level of the wadi, which would otherwise rapidly degrade, and of affording, so to speak, “artesian” vents, up which the water, confined between the beds of the “Nubian” sandstone below, finds its way into the loose sand above. In Sinking wells.sinking wells, spots should be selected where the vegetation in the wadis is of a brighter hue, and where heglig and the dom palm exist. In December, 1871, water was found in many such places, never more than 15 feet below the surface. The trap dyke in the vicinity will provide any quantity of fairly bedded stone with which to line the sandy sides of the well; the way I should suggest, would be, in the first place, to dig through the sand until water be reached, and then to excavate the ground in a circle of say, 24 feet diameter, lining it with a dry stone wall 3 feet in thickness, in this should be built, at intervals, pieces of hard wood, of which there is a large quantity, in order to form a rude ladder; as soon as the water is reached, a Norton’s tube pump should be driven some 6 feet or more; this will prevent the accumulation of insect life, to be found in any open pools in the vicinity, and prevent other pollution; then, when this runs dry, the excavation should be again carried down to the lowering water level, and a well of internal diameter of 14 feet be built with a dry stone wall of say, 2 feet thick (the word in India for this form of well is “butcha”), the Norton tube driven down, and the process repeated as the waters lower. Were it possible to procure lime readily, the well might be sunk from the top, as is so habitually done in India, but the only limestone found in the Bayuda is at the plain of El Mesalima, as mentioned above.
The stone near these wells, and of which as described above, the supply will be practically unlimited, may be used in constructing defensive works, whilst there will be in their neighbourhood large quantities of fuel, and a considerable amount of bush that will serve as fodder for the camels.
A considerable quantity of sheep, milk, etc., may be procured from the neighbouring tribes.
Jebel Gilif.The Jebel Gilif presents a certain source of danger (during the expedition, 1884): this consists of, in places, an almost precipitous face of some hundreds of feet in height, at the foot is an irregular talus formed by the degradation of the face, and by the stones and boulders brought down the “khors” (ravines) with which it is intersected. These “khors” are, in many places, near their debouchure from the mountains, very narrow (in places only one camel can pass at a time), with steeply precipitous sides, the bottom being of granite rock, polished by the materials carried down in the torrents of the rainy season, and in many places half blocked up with boulders and débris. As these “khors” rise to the level of the range they widen out into valleys, well supplied with wood, water, forage, etc., where large numbers of men could be kept concealed for a considerable period.
Report on El Ein.
Situation.El Ein is situated about 130 miles from Debba up the Wadi El Melh. The general trend up the wadi is S.S.W. At El Ein on the western bank, for some 60 miles northwards and a short distance southwards, is a precipitous escarpment of rugged outline, but extremely uniform in height, known as Jebel Makakush. El Ein is a gorge in this, the northern promontory of which is surmounted by a rock of curious shape and is called El Serg.
There are two places where water is obtainable along the route from Debba to El Ein, one called Mahtul about 30 miles from Debba has two wells, and the other is Soteir another 30 miles further on. The latter is the better water, but the quantity is small. On the arrival of the writer the well had been emptied by watering a troop of camels, and his men stated there was not enough water to fill waterskins for from two to three hours. At El Ein there is good and abundant water, while grazing may be found almost anywhere along the Wadi El Melh, but from about 30 miles south of Soteir it lies only along the western side, and is much less abundant than further north.