[Illustration: 314.jpg ONE OF TUE FAÇADES OF THE FORTRESS OF KUBBAN] Drawn by Boudier, from a photograph by Insinger, taken in 1881. Sometimes a son of the reigning Pharaoh, even the heir-presumptive, would condescend to accompany the caravan. Amenemhâît III. repaired or rebuilt the fortress of Kubbân, the starting-place of the little army, and the spot to which it returned. It is a square enclosure measuring 328 feet on each side; the ramparts of crude brick are sloped slightly inwards, and are strengthened at intervals by bastions projecting from the external face of the wall. The river protected one side; the other three were defended by ditches communicating with the Nile. There were four entrances, one in the centre of each façade: that on the east, which faced the desert, and was exposed to the severest attacks, was flanked by a tower. The cataract of Wady Haifa offered a natural barrier to invasion from the south. Even without fortification, the chain of granite rocks which crosses the valley at this spot would have been a sufficient obstacle to prevent any fleet which might attempt the passage from gaining access to northern Nubia. [Illustration: 345.jpg THE SECOND CATARACT BETWEEN HAMKEH AND WADY HALFA] The Nile here has not the wild and imposing aspect which it assumes lower down, between Aswan and Philae. It is bordered by low and receding hills, devoid of any definite outline. Masses of bare black rock, here and there covered by scanty herbage, block the course of the river in some places in such profusion, that its entire bed seems to be taken up by them. For a distance of seventeen miles the main body of water is broken up into an infinitude of small channels in its width of two miles; several of the streams thus formed present, apparently, a tempting course to the navigator, so calm and safe do they appear, but they conceal ledges of hidden reefs, and are unexpectedly forced into narrow passages obstructed by granite boulders. The strongest built and best piloted boat must be dashed to pieces in such circumstances, and no effort or skilfulness on the part of the crew would save the vessel should the owner venture to attempt the descent. The only channel at all available for transit runs from the village of Aesha on the Arabian side, winds capriciously from one bank to another, and emerges into calm water a little above Nakhiet Wady Haifa. During certain days in August and September the natives trust themselves to this stream, but only with boats lightly laden; even then their escape is problematical, for they are in hourly danger of foundering. As soon as the inundation begins to fall, the passage becomes more difficult: by the middle of October it is given up, and communication by water between Egypt and the countries above Wady Haifa is suspended until the return of the inundation. By degrees, as the level of the water becomes lower, remains of wrecks