48 .-- Section of dike at Wady Gerraweh.] In order to reach the diorite and grey granite quarries of the Hammamat Valley, the Pharaohs caused a series of rock-cut cisterns to be constructed along the line of route.

Some few insignificant springs, skilfully conducted into these reservoirs, made it possible to plant workmen's villages in the neighbourhood of the quarries, and also near the emerald mines on the borders of the Red Sea.

Hundreds of hired labourers, slaves, and condemned criminals here led a wretched existence under the rule of some eight or ten overseers, and the brutal surveillance of a company of Libyan or negro mercenary troops.

The least political disturbance in Egypt, an unsuccessful campaign, or any untoward incident of a troubled reign, sufficed to break up the precarious stability of these remote establishments.

The Bedawin at once attacked the colony; the workmen deserted; the guards, weary of exile, hastened back to the valley of the Nile, and all was at a standstill.
The choicest materials, as diorite, basalt, black granite, porphyry, and red and yellow breccia, which are only found in the desert, were rarely used for architectural purposes.