* The gold-mines and the method of working them under the Ptolemies have been described by Agatharchides; the processes employed were very ancient, and had hardly changed since the time of the first Pharaohs, as is shown by a comparison of the mining tools found in these districts with those which have been collected at Sinai, in the turquoise- mines of the Ancient Empire.

This was the Nubian gold which was brought into Egypt by nomad tribes, and for which the Egyptians themselves, from the time of the XIIth dynasty onwards, went to seek in the land which produced it.  They made no attempt to establish permanent colonies for working the mines, as at Sinai; but a detachment of troops was despatched nearly every year to the spot to receive the amount of precious metal collected since their previous visit.  The king Usirtasen would send at one time the prince of the nome of the Gazelle on such an expedition, with a contingent of four hundred men belonging to his fief; at another time, it would be the faithful Sihathor who would triumphantly scour the country, obliging young and old to work with redoubled efforts for his master Amenemhait II.  On his return the envoy would boast of having brought back more gold than any of his predecessors, and of having crossed the desert without losing either a soldier or a baggage animal, not even a donkey.

[Illustration:  314.jpg ONE OF TUE FACADES 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.  Amenemhait III. repaired or rebuilt the fortress of Kubban, 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 facade:  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]