Now the ascent becomes so steep that Harvey is compelled to stop at frequent intervals to cool his engine. The rapid reports of the exhaust echo in the still mountain air like the clatter of a machine-gun. Still the interminable trail leads on, dropping down into the beds of dried-up rivers, crossing by narrow bridges the _arroyos_ cut in the soil by smaller torrents, crawling cautiously around rocky shoulders, skirting the brinks of chasms whose walls drop away from our wheels half a hundred fathoms sheer, scaling the face of towering cliffs by a series of narrow shelves hewn from the living rock, but climbing, climbing, always climbing, that portion of the road which is yet to be traversed unwinding itself before us like an endless yellow ribbon as it reaches toward the higher levels. It seems as though we would never reach our destination; but at long last, topping a final rise, we debouch upon a lofty table-land, sprinkled with palms and sparsely covered with ill-nourished grass, with the great peaks of the Djebel Matmata rising in a rocky rampart all around. Bled Kebira, the largest of the troglodyte towns, is on the plateau, just ahead, but to reach the far older and fortified village of Gelaa Matmata, now deserted, we must leave the car and climb another half a thousand feet or so, for it is perched on the very summit of the mountain. Even when we gain this fortress in the clouds there is no sign of human habitation, barring a few fortifications, now in ruins, but the flanks of the mountains are pitted with what appear to be the entrances to gigantic rabbit-burrows, which are in reality the doorways to the former homes of the cave-dwellers.