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 indeed in most other directions, unless when approaching the Nile, you enter on the Desert at once. The burying-ground around the city is all in sand; and the first step beyond this, the ground is as completely barren and desolate as it can be in the heart of the Great Sahara itself. The route through might be almost traced by the skeletons and bones of camels to be seen all a long; thousands and thousands lie bleaching by the wayside. The surface of the ground is salt, and covered with rounded pebbles, chiefly the Egyptian agate, and sea-shells. Pieces of petrified wood, often of considerable magnitude, lie strewed around: and when the lime-*stone rock shows itself above the sand and gravel, it is generally perforated by the pholas, or some other variety of marine borer. The rocks, like those near Cairo, abound in petrifactions—beautiful specimens of crabs and stars-fishes being amongst the most abundant. Little nimble fairy-*looking lizards, in color very like the surface of the ground around them, are occasionally to be seen in the Desert; also a curious variety of serpent, with two horn-like processes protruding from the forehead. There are numberless vultures and carrion crows, which feed on the dead carcases of the animals who so frequently perish on the way across. Besides these, scarcely a living thing is to be seen. Here and there are considerable quantities of the poisonous henbane, and half-way betwixt Suez and Cairo numerous bushes of the prickly acacia or camelthorn. Just beyond the centre station is what is called 'the tree of the Desert;' solitary acacia, about one and a half feet in diameter, and ten feet length of stem, with a large thick bushy round top. This is seen at a vast distance from each side: to the weary wayworn traveler it seems almost impossible to approach it, he riding for hours after first catching sight of it without apparently coming nearer it.

The beautiful phenomenon known to sailors as 'looming,' to naturalists as mirage, equally visible in extremely cold as in warm countries, is often seen in great perfection betwixt Cairo and Suez. It is occasioned by the unequal temperature and refractive powers of different strata of the atmosphere—objects being invariably elongated or depressed, or a succession of images of them exhibited one over another. Scoresby gives drawings of images of ships and icebergs being seen by him in the arctic regions—direct or reversed, or the one and the other alternately—high up in the air. Pools, and lakes of water, are occasionally seen to fill up the hollows or valleys; and this is the shape the illusion most frequently assumes. Three of us together once saw so perfect a picture of a pool surrounded by lofty rocks and hills, by which there were two tall men in black fishing, that, but for the fact that we had traversed the ground before, and knew that there was no such thing in existence, no reasoning short of that which induced us to refuse the testimony of ourselves could have persuaded us that it was all deception. The fishers turned out to be a couple of crows, the rocks and trees a few stones and shrubs—not half so many inches in reality as they seemed feet in altitude. On another occasion, the low hillocks to the south of the centre station rose into stupendous cliffs—a noble river cleft its way through a chasm by which they were disrupted, and was received in a finely-wooded lake at their base. It seemed some three or four miles off—the whole was occasioned by the distortion of objects not two hundred yards away. So constantly had we witnessed these exhibitions in April 1840, that the Red Sea was visible for nearly an hour