Sunday, June 30.—At sunrise began our journey through valleys of sand, bounded on each side, and every where intersected by high sand hills. We had to pass over several of these, to our great annoyance. Our water was low, half a gerba only was left, and we began to be a little uneasy at the chance of losing our way, or the well being filled up. Our fears were soon removed. We saw the well at a distance, and found it full of good water on our arrival. The name of the valley is Tigidafa. Much of the equisetum-leaved plant grows here, and four or five date trees overshadow the well. We halted during the heat of the day. The Mamelouk very unwell with ague and affection of the liver, probably arising from the want of his usual quantity of sour lackbi. In Mourzuk we were told he used to drink all he could procure. About four we moved along the summits of several of the highest ridges, and descended some of the most difficult passes. About sunset arrived at a large plain, with a little feeding for the camels. Here we halted. The grasses have long tapering roots, but not finely divided into fibres; each fibre descends perpendicularly, and does not creep along the surface. It is covered with a fine velvety epidermis, and that again with fine particles of sand, so as to give it the appearance and elasticity of twine finely coiled up. None of the plants I saw had creeping roots, but all long and tapering; thus forming but a weak barrier to the fixing of the sand. Tuesday, July 2.—Our course over and among the sand hills, and sandy walls, or barriers, like falls in a river, every here and there running across the valleys. Our guide, whom we now styled Mahomet ben Raml, or son of the sand, was almost always on before, endeavouring to find out the best way. We could detect in the sand numerous foot-marks of the jackal and fox, and here and there a solitary antelope. In some of the wadeys there were a great many fragments of the ostrich egg. Clapperton and Mahomet ben Hadje went a long way out of the tract. They followed the footsteps of some camels, and went on ahead of us. Our road lay in a different direction from theirs: we were therefore separated a considerable distance from each other. When we saw no appearance of them we halted, and sent the servants in search. The moment was trying: they were in the midst of sand hills, without provisions or water; but, luckily, it was not long; our searchers soon detected them from the heights. About mid-day halted in a valley, and remained under the shade of some date trees for a few hours. Set out again in the afternoon. The heat was oppressive, and our travelling was difficult. We next came to an extensive level plain, which was some refreshment; for we were completely tired of ascending and descending sand hills. Our servants strayed; they went on a tract which was pointed out to them as the right one, and, before we were aware of the error, they went so far that we were not able to send after them.