Sixteen or eighteen hours must be allowed to reach the summit of the ancient volcano, and one does well to spread them over two days if one does not want to leave any camels on the way. The first stage should get one to Fada, a little pasturage at the bottom of a ravine accessible to camels, and where the animals should be allowed to rest and feed. Afterwards a fairly long halt should be made at an altitude of about 6000 feet, to renew the supply of water at the natural cistern of Lantai-Kourou, for there is no hope of finding water in the interior of the crater; the operation is a long and toilsome one, for the track leading to the reservoir is inaccessible except to men. Along the whole way there is hardly any vegetation, such as there is being confined to deep ravines, almost always inaccessible, except at the pasturage of Fada, on account of the steepness of their sides. Towards the foot of the mountain only stunted plants are to be found, with tiny leaves often sharpened into thorns; while nearer the top the boughs are thicker, the bark tenderer, the sap more abundant, and the leaves longer and greener. No trees are to be found on Emi Koussi in the crater itself; on the other hand, the herbaceous vegetation is comparatively abundant, and marked especially by the “erendi,” a yellow-flowered plant reminding one of the St. John’s wort of our regions. We bivouacked, in a good position for observing all the approaches, in the midst of these bright-hued flowers, and I cannot tell you with what fascinated eyes we gazed on them, for none of us had seen their like for three long years. The temperature was mild and cool like that of a fine spring in France; but in the clear sky there were no birds, and the sight of the scowling cliffs around us soon broke the charm under which our fancy would have gladly lingered. We stayed only three days in the crater of Emi Koussi. The afternoon of the first day was devoted to the exploration of a pit, 300 yards deep and 2 miles in diameter, which was once the chimney of the volcano. A vast expanse of carbonate of soda covers the bottom, which one can reach only by a very steep path. The second day was spent, firstly in exploring, both inside and out, the western slopes of the crater, where there is a natural cistern that enabled us to make a fresh provision of water, though the track leading to the reservoir is very perilous for the camels; and afterwards in taking certain measurements, such as the height of the cliffs and the depth and extent of the central pit, called by the natives Era-Kohor, or Natron Hole. The third day was given up to explorations in several directions, which allowed us to visit some recently abandoned troglodyte villages, to capture two prisoners, and to reach the summit of the northern side of the volcano, a point from which the whole of the Tibestian mountains can be seen.