418 JOURNEY TO CENTRAL AFRICA.

me. Whether they were caused by breathing a more rarefied atmosphere,— for the plain was nearly fifteen hundred feet above the Nile level — in a heat more than usually intense, or by an attack of that malady which Richardson aptly calls the " intoxication of the Desert," I cannot decide.

After leaving Bir Abou-Seray, we continued our slow descent of the northern side of the mountain range, by a winding valley, following the dry bed of a summer river. The mountains were a thousand feet high and linked in regular ranges, which had a general north-east and south-west direction. The landscapes of the day were all exceedingly wild and picturesque. The vegetation was abundant along the banks of the river-bed, the doum-palm appearing occasionally among the groves of thorn and nebbuk. In some places the river had washed the bases of the mountains and laid bare their huge strata of rock, whose round black masses glittered in the sunshine, showing the gradual polish of the waves.

Towards noon the pass enlarged into a broad plain, six miles in diameter, and entirely bounded by mountains. To the northeast it opened into another and larger plain, across whose blue surface rose the pyramidal peaks of a higher mountain chain than I had yet seen. Some of them were upwards of two thousand feet in height. The scenery here was truly grand and imposing. Beyond the plain we passed into a broader valley, girdled by lower hills. The river-bed, which we crossed from time to time, increased in breadth and showed a more dense vegetation on its banks. We expected to have reached another well, but there was no sign of it at sunset, and as I had already found that my guide, Mohammed, knew nothing of the road, I encamped at once