DESERT INTOXICATION 415 several hours, we entered a narrow valley leading into its depths. The way was stony and rough, and we travelled for three hours, constantly ascending, up the dry bed of a summer stream. The mountains rose a thousand feet above us in some places. Near the entrance of the valley, we passed an Arab watering a large flock of sheep at a pool of green water which lay in a hollow of the rocks. After ascending the pass for nearly four hours, we crossed the summit ridge and entered on a high table-land, eight or ten miles in length and entirely surrounded by branches of the mountain chain. The plain was thinly covered with grass, mimosas and nebbuk, among which a single camel was browsing. At night we reached the opposite side, and encamped at the foot of a lofty black spur of the mountains, not far from a well which Mohammed called Bir Abou-Seray. During the night I was troubled with a heavy feeling in the head, and found it almost impossible to sleep. I arose with a sensation of giddiness, which continued all day. At times I found it very difficult to maintain my seat on the dromedary. It required a great effort to keep my eyes open, as the sunshine increased the symptoms. This condition affected my mind in a singular manner. Past scenes in my life revived, with so strong an impression of reality, that I no longer knew where I was. The hot, yellow landscape around me, was a dream ; the cries of my camel-drivers were fantastic sounds which my imagination had conjured up. After a most bewildering and fatiguing day, I drank several cups of strong tea, rolled myself in a thick cotton quilt, and sweat to distraction until morning. The moisture I lost relieved my head, as a shower clears a sultry sky, and the symptoms gradually left