remarkably wild passage through the sandstone cliffs which we were about to descend: it is called Rálle. The first part of it was more rough than wild, and the cliffs of the sandstone rather rugged and split than precipitous and grand; but after half an hour’s descent it bore evident traces of the waters that descend from the heights, and which being here collected into one mighty stream, with enormous power, force their way down through a narrow channel. The defile was here encompassed by rocky walls about a hundred feet high, half of which consisted of sandstone, while the other half was formed by a thick deposit of marl; and a little further down it was not more than six feet wide, and the floor and the walls were as smooth as if they had been cut by the hand of man; but the course of the defile was rather winding and not at all in a straight line, forming altogether a pass easily to be defended by a very small power, and affording the Tawárek a stronghold against any designs of conquest on the side of the Turks, although it does not form the frontier, but is regarded as entirely belonging to Fezzán. At the narrowest point Tawárek, as well as Arab travellers had recorded their names. Where the channel began to widen, there were some curious narrow gaps or crevices on both sides, the one to the right, with its smooth rounded surface, bearing a great similarity to the famous Ear of Dionysius in Syracuse. The walls contained strata of chalk and ironstone; and Overweg found here some interesting petrifactions. The crevice to the left was less deep, and rather resembled a cell or chamber. Having here waited some time for the boat to come up, we started together, but had still to get through two more narrow passes of the wadi, and at four o’clock in the afternoon entered another very narrow defile, the steep cliffs forming it being covered with inscriptions. At length, after a descent of altogether four hours, we emerged into the open plain some 600 feet below, and had a wide view of the high precipitous cliffs of the plateau, stretching out in several buttresses into the plain, which is interrupted only by detached hills. Amongst these was a rather remarkable one upon a terrace-like base, and opening with three caverns towards the roadside. Ascending the terrace, I found the westernmost of the caverns vaulted, as if by art, in the shape of a large niche, but it was a little filled with sand; I found, however, no inscriptions nor anything but four round holes, about nine inches in diameter, hollowed out in a slab on the terrace in front of the cavern. Beyond this hill, where Hatíta told us that he had once passed the heat of the day with ʿAbd Allah (Clapperton) and the tabíb (Oudney), the country is quite open towards the north. About sunset we encamped in the deep Erazar-n-Tése; there were a few talha-trees and some herbage.