This night seemed cooler than those which had preceded it: my rest was disturbed by the appearance of a serpent, which suddenly awoke me, and had nearly reached my head when I perceived it. I rose in haste; the reptile was alarmed by the noise I made, and returned immediately to its hole, which was not far distant: this serpent was five feet and a half long, and as thick as the thigh of a boy twelve years old. The idea of so unpleasant a neighbour banished sleep for the remainder of the night: my travelling companions also experienced similar visits, and appeared no less dismayed by them than myself. The whole of the 6th was employed in watering our camels; we procured for them stalks of _hedysarum-alhagi_, and branches of the tamarisk, which grows on the plain at some distance from the wells: these were quickly devoured. This night we lay down as on the preceding, and I was again annoyed with the sight of enormous serpents. At four o’clock in the morning of the 7th, we directed our course to the N. N. E., among the chain of sand-hills called Helk; but these are not by much so high as those we had crossed the day before. Sidi-Aly, whom I questioned on the subject, and who at times vouchsafed an answer, assured me that in none of his former travels in the Soudan had he seen such lofty sand-hills; his route had always been more northerly. As our road was better than that of the preceding day, we travelled at least two miles an hour. About half past eleven we halted at the foot of the chain, on a somewhat hilly plain of grey gravel, the finest I had yet seen. On the 8th, we set out at four in the morning, taking a northerly direction, over a sandy and tolerably level soil. Near noon we halted in a plain of firm ground, covered with sharp flints as flat as slate, and mixed with small gravel; this plain is surrounded by gently swelling downs. I longed to emerge from these frightful deserts, where the only indications of animated nature were the distressing east wind, and some light-footed antelopes, which swept across them with the rapidity of an arrow. I saw in several places skeletons of these animals, dried up by the burning sun; they had undoubtedly died of thirst. On the 9th, at about one in the morning, we pursued our journey northwards; the soil was covered with black gravel, and studded with pointed rocks of the same colour. A little before eleven we halted at the wells of Amoul-Taf, situated among rocks of grey granite; it was necessary to open them; they are only four feet deep, the water sweet, but not plentiful; tamarisks flourish in the neighbourhood. We surrounded these wells with straw to prevent the sand from falling in. The camels were but half watered, and we filled our leathern bags in preparation for departure.