These three heads, each of which has numerous feeders, join together in a small plain at the south-east foot of O Shakafa, a remarkably prominent peak practically isolated from the mountains near it, and from this point onwards the main drainage channel is called Wadi Meisah. The little plain where the three head wadis unite is covered with trees, and has almost the aspect of a park; it is 455 metres above sea-level. Curving eastward and northward close round the foot of O Shakafa, Wadi Meisah receives from the south the =Sarob Kwan=, a short and very broad wadi leading to an easy pass into Wadi Didaut, and then winds about as a narrow gorge shut in by high hills. Just where it leaves the foot of O Shakafa, there is a track from the east side of the wadi over a very easy pass into the head of Wadi Orgem. =Bir Meisah= is a well sunk in the alluvium of the wadi bed about three kilometres below O Shakafa, and 410 metres above sea-level. When I visited it in March 1908, it was filled with downwash, and as there was plenty of water in the rock basins of the mountains further north there was then no necessity to dig it out. The Arabs say the well is about ten metres deep, and its water is not so good as that obtainable from the galts, so that they only open it when the other sources in the neighbourhood are exhausted. Two gullies entering Wadi Meisah from the east, just below the well, each contain large galts, called =Meis-heit-ar=, a short distance up from their mouths; these were both yielding good and plentiful water supplies in the spring of 1908. After winding about among the hills for ten kilometres below the well, Wadi Meisah receives a feeder from the west having three heads. The northern one, =Akla Da-Aiyob=, is a very sandy gully, in fact it is choked by drift sand, and all the trees in it are dead. The central one, coming westward from among high hills, is called =Hanqun Ra-ub=, while the southern one, called the =Wadi Eqaiyib=, is only separated from Meisah at its head by an easy pass, so that it almost forms a loop of Meisah itself. To go from Bir Meisah to Bir Um Bishtit, one crosses this pass into Wadi Eqaiyib, then up Akla Da-aiyob, and over another easy pass at its head into Wadi Um Bishtit; the total distance between the two wells by this route is only sixteen kilometres.