We were roused from our refreshing sleep as early as two o’clock after midnight; but this was a mere sham of our camel-drivers, who feigned making up for the loss of yesterday, and after all we did not get off early. Our road carried us from wady to wady, which were generally separated from each other by a defile, occasionally presenting some difficulty of passage. We left a castle of Roman workmanship, as it seemed, in the distance to the left, and further on to the right a slight stone wall called Hakl el Urínsa, dating from the petty wars between the Arab tribes. We had already passed a few small ethel-bushes; but now we came to a most venerable-looking old tree called Athelet Si Mohammed fi Useát, spreading out its weather-beaten branches to a considerable distance: under this I sat down quietly for a while, waiting for our people, who were still behind. The caravan at length came up; and continuing our march, we soon passed on our right hand the chapel of a great Merábet of the Welád Bu-Séf, called Si Rashedán. The Welád Bu-Séf in general enjoy great authority with the other tribes for their sanctity of life and purity of manners; they allow no stranger to come near their villages, but pitch a tent for him at a distance, and treat him well. The Welád Bu-Séf are remarkable for the excellent breed of their camels, which they treat almost as members of their families. It is curious that this tribe, intent upon right and justice, has waged war incessantly from ancient times with the Urfílla, the most warlike and violent of the tribes of these regions. It is difficult to make out whether they are related to the Welád Bu-Séf of the western part of the desert, who are likewise distinguished by their peculiar manners, but who it seems would scruple, on religious grounds, to call a man ʿAbd eʾ nebi (Slave of the Prophet), which is the name of the ancestor of the Eastern Bu-Séf. Emerging from a defile, upon high ground, early in the afternoon, we obtained a view over Wady Zémzem, one of the most celebrated valleys of this part of North Africa. It runs in general from west to east-north-east, and is furnished with a great many wells, the most famous of which are el Abiadh, Sméla, Nákhala, Urídden, Halk el Wady, and, a little further down, Téder. In half an hour we encamped in the valley, full of herbage and with a goodly variety of trees. A caravan coming from the natron-lakes, and carrying their produce to Tripoli, was here encamped. I could not withstand the temptation of ascending, in the afternoon, a projecting eminence on the south side of the valley, which was broken and rent into a great variety of precipices and ravines; but its summit, being on a level with the plateau, did not afford me such a distant view as I had expected. The cliff was formed of strata of marl and gypsum, and contained many fossil shells.