484 NORTH-WEST AFRICA. is not only shorter than in nny other part of the desert, Fezzan being distant less than GOO miles from Kaueni, but it is also occupied by several oases, such as the Kawar group, following in succession along the route. Hence this commercial highway forms a natural parting line between the eastern section of the desert, of which Tibesti is the central mass, and the western division, occupied by the heights of Air. Nor is the ethnological limit between the Tibbu and Tuareg populations far removed from this chain of oases. It oscillates a little to the west, shifting to and fro with the vicissitudes of the chronic warfare maintained by the hostile border tribes. After crossing the " Gates " leading southwards from the southern plateaux of Fezzan, the caravans enter a reddish plain, which slopes imperceptibly in the direction of the south. The Gates stand at an elevation of about 2,160 feet, or 1,250 above Lake Tsad (S)10 feet), towards which the trade route runs almost in a straight line, and which is distant 570 miles. But this absolute incline of 1,2-jO feet is unequall}' distributed. Relatively more considerable in the northern part of the plateaux, it gradually falls almost to a dead level in the central region of the desert, where a uniform altitude of from 1,170 to 1,330 feet is maintained across four degrees of latitude. The undulating plateau rolls away in great billows, above which api)ear on the horizon regular tables of sandstone and limestone formation. Here and there in the dreary waste are seen a few groups of arid cliffs, which seem burnt up or still burning, so fiercely are the solar rays reflected from the glowing surface. The few hollows occurring in the rocky or argillaceous ground between the cliffs or sandhills contain somewhat more moisture than the surrounding spaces, and here are found the only pernument or temporary wells occurring along the track of the caravan route. The largest of these depressions are occupied by a few oases, such as that of Yat, called by the Arabs Suhiya, or the " joyful," which runs east and west for a distance of 12 miles, and nearly 2 north and «oulh. The traveller arriving from the vast plains absolutely destitute of vegetation might be tempted to speak of Yat as a " forest," so striking is the contrast presented by its thickets of wild dates, acacias, and grassy glades with the surrounding sands. The diim-palm also grows in great abundance in this oasis, where it reaches its northern limit in this direction. The Yeggeba oasis south-west of Yat is much smaller and less peopled, while that of Siggedim, although abounding in dates, was no longer inhabited at the time of Naehtigal's ^'isit in 1870. But that of Jebado, situated to the north-west, is occupied, like Yat, with Teda and Kanuri communities. It has been once only visited by a European in 1862, when this last station of the Tedas and their Kanuri kinsmen in the direction of the west was traversed by Beurmann. Kawar. Kawar, separated by a stony hamada from Yeggeba, stretches in the direction from north to south for a distance of about 50 miles. The caravan route traverses It from end to end between a long avenue of palms interrupted here and there by
