We must not, however, libel even the Sandy Desert, by producing the impression that it is all barren and comfortless.  Though far more difficult to travel over than the Hamadah, it possesses the inestimable advantage of having water every day once at least.  A little after noon, indeed, we passed two lakes; one small, and the other of considerable dimensions, containing sweet water, and bordered by a fringe of palm-trees.  At times there is very good herbage for the camels.  The most frequent shrub on which they browse is the resou, which has small ears of grain, eaten also by men as food.  Traces of animal life, as I have observed, are few; but we saw this day two broken ostrich-eggs.  How they came there it is difficult to say:  no traces or footmarks have been remarked.

At length I had begun to find drinking a necessity.  During these days of sand I imbibed more than during the whole of the rest of the journey.  The eating of dates added to my thirst; and the blacks complained of the same thing.  Dates are much better in the winter, and keep the cold out of the stomach; but I should recommend all Saharan travellers to eat as few of them as possible, at any season of the year.

During this last day, beyond the expanse of sandy waves through which we swam, as it were, had risen ahead some very conspicuous mountains.  Even at five in the morning we could see detached along the line of the horizon the highest and most advanced portion of the edge of the plateau of Mourzuk.  In three hours the white line of cliffs came in view, looking like a stretch of black-blue sea, contrasting strangely with the sparkling white-sand undulations that stretched to their feet.  Some of us thought that an inland sea—­never before heard of—­had rolled its waters athwart our path, so perfect was the illusion.  The heavens, this day particularly, attracted our attention.  What a sky! how beautiful!  The ground was a soft, light azure; and on its mildly resplendent surface were scattered loosely about some downy, feathery clouds, of the purest white—­veils manufactured in celestial looms!

We expected to reach our premeditated halting ground about noon, or before, these cliffs seeming so near.  But as day wore on, new expanses of glittering desert seemed to stretch out before us; and every hillock gained disclosed only the existence of new hillocks ahead.  Meanwhile the hot wind still blew with unremitting violence, scorching our faces, and penetrating to the inmost recesses of our frames.  The poor blacks, who were on foot, gazed wistfully ahead, and ever and anon called to those who were nodding on the camels, as if stunned by the heat, to tell them if they might hope for rest.  I found my eyesight dimming, and deafness coming on.  The thermometer was plunged into the sand, and the mercury instantly mounted to above 130 deg..

At length we sighted the wady, stretching like a green belt between the sand and the mountains beyond.  We found that we had been traversing an elevated swell of the desert, for we were full three quarters of an hour descending to the level of the valley.