The whole afternoon we rode through the extensive plain, El Gôs, probably so called from the great sand-downs, so characteristic of this region, and which assume, in the southern districts, a peculiar form. They have almost all the form of a crescent, opening toward the south-west, so that one looks from the road into a number of amphitheatres, the steep sand-walls of which rise ten feet with the north wind, which blows inside, and clears away the sand, which would otherwise rapidly fill the cavity, from the inner field. How quickly these moveable sand structures change their place, is shown by the traces of the caravan road, often lost beneath high sand-hills. Toward eight in the evening we left the Gebel Barqugrês to the left, and stopped for the night at a short distance from the Gilif mountains. On the 3rd of May we passed through the Wadi Guâh el ’âlem, much overgrown with trees, into the mountains, principally porphyritical, and like all original mountains, containing more vegetation than the sandy plains, by the longer holding of the precipitated damp and scarce rains. After three hours we came into Wadi G’aqedûl, luxuriantly overrun with gesh and prickly trees of every kind--sont, somra, and serha. We here found grazing herds of camels and goats, particularly in the neighbourhood of the water, which has also attracted numerous birds, among them ravens and pigeons. In the wide, deep-lying grotto, which may be 300 feet in diameter, and is enclosed by high walls of granite, the water is said to remain three years without requiring replenishment. It was, however, so foul and bad smelling, that it was even despised by my thirsty ass. The drinkable water lies farther up the mountain, and is difficult to be obtained. We here forsook the northerly direction, which the wells after Gebel Nusf had obliged us to take, and went westerly by the Gilif mountains, in Wadi el Mehêt, crossed the dry Chôr el Ammer, whence the way to Ambukôl branches off, and encamped at night after ten o’clock in the Wadi el Uêr, called by others the Wadi Abu Harôd. From this place the Gilif mountains retreated eastward again for some time, and only left sand-hills in the foreground, by which we travelled on the following morning. To the W.N.W. we saw another chain, no longer called Gilif; a single projecting double-pointed mountain was called Miglik. The great creek of the Gilif chain, filled with sand-rock, is two hours’ journey broad; then the way leads northward into these mountains, which is called Gebêl el Mágeqa after the well of Mágeqa.