Foremost among the phenomena peculiar to this zone we must place those famous tempests which, in default of humid clouds, traverse with startling swiftness the changing surface of the Desert, driving before them whirlwinds of burning sand, and striking the traveller's heart with a sense of unconquerable awe. The wind of the Desert is called by the Arabs the _choum_ or _khamsin_; but is more generally known in European books as the _Simoun_, _Simoom_, or _Samoun_. It is the _Samiel_ of the Turks; and, under a somewhat milder form, the _Scirocco_ of the Mediterranean. Wherever, or however it blows, it is a pernicious and hateful wind; the blast, in all probability, which destroyed the hosts of Sennacherib at the bidding of the Divine Word,-- "The angel of Death spread his wings on the blast, And breathed in the face of the foe as he passed. And the eyes of the sleepers waxed deadly and chill, And their hearts but once heaved, and for ever grew still." Torrents of burning sand sweep before it, a thick veil of darkness envelopes the firmament, and the sun assumes a blood-red hue. "That crimson haze By which the prostrate caravan is awed In the red desert when the wind's abroad."[58] When the Simoom rises, says M. Martins,[59] the air is filled with dust of such extreme fineness that it makes its way through objects hermetically sealed, penetrates into the eyes, the ears, and the organs of respiration. A burning heat, like that which breathes from the mouth of a furnace, possesses the air, and paralyzes the strength of men and animals. Seated on the sand, with their backs turned to windward, the Arabs, wrapped in their burnous, wait with fatalistic resignation the end of the torment; their camels crouching, exhausted, panting, stretch their long necks upon the scorching soil. Seen through this powdery haze, the sun's disc, shorn of its beams, shows pale and ghastly as that of the moon. Fortunately, the phenomenon never prevails over any very considerable area, and beyond its limits the atmosphere remains serene and calm; so that travellers who have watched it approaching in the form of a reddish cloud, without being able to calculate on its direction, have often escaped with no worse result than a panic, and have only witnessed its terrible effects at a distance.