By the middle of the afternoon we were again on our way, which led through the deep and winding valleys of three mountains of calcareous stone, which indicated the proximity of the river, and over hills of deep sand, with which the eddies of the wind had in many places filled those valleys.  Since we left Morat till we came to these mountains the granite hills had become rarer, others of calcareous stone here and there presented themselves, and the level of the desert was constantly ascending[79] I have no doubt that the level of the interior of the desert is lower than the bed of the river.

During the passage over these hills several of the camels gave out, that of my black slave among the rest.[80] Four hours after sunrise we came to a valley, where there was here and there some herbs of the desert, where we stopped to let the camels eat, they having fasted since we left El Medina.

We were obliged to look among the rocks for shelter from the sun, each one arranging himself as well as he could to eat durra bread and drink warm water, and sleep as soundly as possible.  During the course of last night we fell in with a caravan coming from Assuan; we pressed round them to buy something to eat; we asked for dates and flour to make bread, but they had nothing of the kind that they could afford to part with.

We stayed at the rock before mentioned till the middle of the afternoon.  On awaking from sleep, I observed two of the Arabs of our caravan busily employed about our guide.  They were a long time engaged in frizzing and plaiting his hair, and finished the operation by pouring over it a bowlful of melted mutton suet, which made his head quite white.  I asked for the meaning of this operation at this time; they told me that we should be at the river to-morrow morning, and that our guide was adorning himself to see and salute his friends there.  He appeared to be highly satisfied with the efforts of his hair-dressers to make him look decent, and it must be confessed that he made a very buckish appearance.

As soon as our guide had finished his toilette, he mounted his dromedary and took his post in front, and we set forward.  We marched all night without stopping, which was necessary, as our water was nearly spent,[81] but which distressed greatly that part of our caravan who had no beast to ride.[82] These wretched men had hitherto accompanied us all the way on foot, with little to eat and less to drink.  At present they were almost exhausted with fatigue, hunger and thirst.  Every now and then, one or more of them would throw himself on the sand in despair.  The repeated assurance that the river was near, hour after hour, became less and less capable of rousing them to exertion, and the whip was at length applied to make them get up and go on.[83] They demanded water immediately, which we were too short of ourselves to give them, as we feared every minute that our camels would drop, which would render every drop of water we had as precious as life.