Huge prostrate blocks of porphyry and basalt, which have been launched from the impending scarps, and now reduce the channel to this narrow passage, are in places so heaped and jammed together by some mighty agency, as to form spacious and commodious caverns. In the rainy season especially, these doubtless prove of wonderful convenience to the wayfarer; and no tent arriving until late the following day, the re-assembled party were fain to have recourse to them for shelter against the fierce hot blast from the Salt Lake, which, unremitting in its dire persecutions, now blew directly up the ravine. But the rocks soon became too hot to be touched with impunity, and the oblique rays of the sun, after he had passed the meridian, darting through every aperture, the caves were shortly converted into positive ovens, in which the heat, if possible, was even more intolerable than ever. Unlike former stations, however, there was, in this close unventilated chasm, a luxurious supply of water to be obtained from the living rill which murmured past the entrance, and although raised to the temperature of a thermal spring by the direct influence of the solar rays, and withal somewhat brackish to the taste, it was far from being pronounced unpalatable. Notwithstanding that the neighbourhood afforded neither the smallest particle of forage nor of fuel, it became necessary, in consequence of the non-arrival of one half of the camels, no less than from the exhaustion of many of the party, to halt a day in the hot unhealthy gully; and this delay afforded to the treacherous creese of the lurking Bedouin an opportunity of accomplishing that which had only been threatened by drought and famine. The guides objecting strongly to the occupation of the caves after nightfall, on account of the many marauding parties of Eesah and Mudaito, by whom the wady is infested, every one, as a measure of precaution, slept in the open air among the baggage, half a mile lower down the ravine, where the caravan had halted. The dry sandy bed of the stream was here narrow, and the cliffs--broken for a short distance on either side into hillocks of large distinct boulders--again resumed their consistency after an interval of one hundred yards, and enclosed the camp in a deep gloom.