Tractors towed the rigs at Ain Dar on multi-wheeled steel platforms from one location to the next, derricks still erect. This saved days of installation time, for the cellars could be prepared in advance and a supply of water insured by drilling a shallow well to the aquifer. Geologists were always present when a core (a cylinder of rock taken from the well by a special bit) was brought to the surface. Although Bedu (nomads) used dried camel dung as fuel, town dwellers preferred brushwood. Sometimes foraging trips for the best kind (arfaj) covered many miles and several days.