country still further, the thorny acacia trees being the principal reserve camel food in rainless years. That so many Ababda are settled in and near the Nile Valley is possibly in part due to their having been driven from the desert by the growing scarcity of trees consequent on the prosecution of the charcoal industry in the past. * * * * * [Footnote 33: The mountains and hills will be found described in fuller detail in Chapter VI.] [Footnote 34: The altitudes refer to the highest points of the groups.] [Footnote 35: This is the altitude of Shendib, the highest of the group in Egypt; but the peaks of Asotriba, which is part of the same mass lying within the Sudan, rise considerably higher.] [Footnote 36: In the map on Plate I, I have shown the watershed crossing directly from Gebel Soaorib across the high intervening mountains to Gebel Is, which is how it appeared to me from my station on Hadal Aweib Meisah. But Mr. Morrow Campbell’s map (referred to on p. 15) shows the heads of Wadi Soaorib to extend further west than I could see them; and if this is correct, as it probably is since Mr. Morrow Campbell doubtless approached the watershed more closely than I did, the watershed between Gebel Soaorib and Gebel Is lies further west than I have shown it on Plate I. In drawing the wadis on the geological and tribal maps on Plates XX and XXVI, I have shown the westward extension of the heads of Wadi Soaorib according to Mr. Morrow Campbell.] [Footnote 37: The wadis will be found described at length in Chapters IV and V.] [Footnote 38: See the _Red Sea and Gulf of Aden Pilot_, published by the Admiralty.] [Footnote 39: See my short paper on the meteorology of the Berenice district in _Survey Notes_, Sept. 1907, p. 325.] [Footnote 40: I have given short accounts of some of these phenomena in _Survey Notes_, April 1907, p. 219, and in the _Cairo Scientific Journal_, May 1908, p. 206.] [Footnote 41: D’ANVILLE, _Mémoires sur l’Egypte_. p. 234.] [Footnote 42: _See_ BARRON and HUME, _Topography and Geology of the Eastern Desert, Central Portion_. Cairo, 1902. pp. 98-104.] [Footnote 43: SCHWEINFURTH, in _Petermann’s Mittheilungen_, 1865.] [Footnote 44: For a fuller description of the water-sources of the region, _see_ Chapter VII.] [Footnote 45: For a fuller account of the geology, _see_ Chapters VIII to XI, and the geological map on Plate XX.] [Footnote 46: SUESS, _The Face of the Earth_. Miss Sollas’ translation. Vol. I. Oxford, 1904. p. 376.] [Footnote 47: Lib. III, 12-14.] [Footnote 48: _See_ DUNN, _Notes on the Mineral Deposits of the Anglo-Egyptian Sudan_, published by the Sudan Government. Khartoum, 1911. p. 15.] [Footnote 49: For a plan of the temple and notes on its inscriptions, _see_ GOLÉNISCHEFF, Une Excursion à Bérénice, _Recueil de Travaux_. XIII (1891). pp. 75-96.] [Footnote 50: MACALISTER, _Geog. Journal_. Vol. XVI (1900). p. 546.]