“Sleep, sir; sleep!” urged Joe. “And you, doctor, do the same yourself: you must have need of rest, for I made you keep watch a little out of time.” The sportsman stretched himself under the awning; but Ferguson, who was not easily conquered by fatigue, remained at his post. In about three hours the _Victoria_ was crossing with extreme rapidity an expanse of stony country, with ranges of lofty, naked mountains of granitic formation at the base. A few isolated peaks attained the height of even four thousand feet. Giraffes, antelopes, and ostriches were seen running and bounding with marvellous agility in the midst of forests of acacias, mimosas, souahs, and date-trees. After the barrenness of the desert, vegetation was now resuming its empire. This was the country of the Kailouas, who veil their faces with a bandage of cotton, like their dangerous neighbors, the Touaregs. At ten o’clock in the evening, after a splendid trip of two hundred and fifty miles, the _Victoria_ halted over an important town. The moonlight revealed glimpses of one district half in ruins; and some pinnacles of mosques and minarets shot up here and there, glistening in the silvery rays. The doctor took a stellar observation, and discovered that he was in the latitude of Aghades. This city, once the seat of an immense trade, was already falling into ruin when Dr. Barth visited it. The _Victoria_, not being seen in the obscurity of night, descended about two miles above Aghades, in a field of millet. The night was calm, and began to break into dawn about three o’clock A.M.; while a light wind coaxed the balloon westward, and even a little toward the south. Dr. Ferguson hastened to avail himself of such good fortune, and rapidly ascending resumed his aërial journey amid a long wake of golden morning sunshine. CHAPTER THIRTY-EIGHTH. A Rapid Passage.—Prudent Resolves.—Caravans in Sight.—Incessant Rains.—Goa.—The Niger.—Golberry, Geoffroy, and Gray.—Mungo Park.—Laing.—René Caillié.—Clapperton.—John and Richard Lander. The 17th of May passed tranquilly, without any remarkable incident; the desert gained upon them once more; a moderate wind bore the _Victoria_ toward the southwest, and she never swerved to the right or to the left, but her shadow traced a perfectly straight line on the sand. Before starting, the doctor had prudently renewed his stock of water, having feared that he should not be able to touch ground in these regions, infested as they are by the Aouelim-Minian Touaregs. The plateau, at an elevation of eighteen hundred feet above the level of the sea, sloped down toward the south. Our travellers, having crossed the Aghades route at Murzouk—a route often pressed by the feet of camels—arrived that evening, in the sixteenth degree of north latitude, and four degrees fifty-five minutes east longitude, after having passed over one hundred and eighty miles of a long and monotonous day’s journey.