[Illustration: A WATER-HOLE IN TIBESTI] [Illustration: FIRST BUTTRESSES OF THE MASSIF OF TIBESTI] Above our heads little patrols, relieved from hour to hour, kept watch on the upper slopes from which the Toubous might have sent undesirable avalanches rolling into our camp. The narrow band of sky that we could see was filled with shining stars, by which I could make the observations needed for calculating the point where we had stopped. The night passed, calm and silent, and next morning, after an hour and a half of fresh efforts, we were able to take up our quarters quietly on the banks of the stream. After which the excellent Mohammed, having received the promised reward, took leave of us to return to his palm grove at Yountiou. But his prudence led him to take quite another route, accessible only to men and goats. All the luggage he carried was a little skin bottle half full of water hanging from his right shoulder, together with a tiny bag containing a few handfuls of dates and about a pound of millet flour. On his left shoulder, swinging triumphantly from the two ends of his staff, were two fine large-sized biscuit tins that glittered in the sun and resounded like beaten gongs whenever they knocked against the corner of a rock. Toubous in small numbers still showed themselves on the cliff-sides, but did not wait for the patrols I sent to parley with them. After a few hours spent in watering the camels and in filling our barrels and skin bottles, we resumed our route towards Miski. The little river of Modra ran hardly more than a mile further down the valley, and the dry bed of the torrent, at first littered with boulders, soon turned into a fine winding road of sand from 200 to 300 yards wide. Twenty miles further on we had to leave the river-bed and plunge into a chaos of little ridges of schist, intersected by narrow valley-ways leading into valleys that came down from neighbouring high mountains of an altitude exceeding 9000 feet: our camels had much trouble in making headway among sharp edges of slaty rock upturned almost vertically. They zigzagged from pass to pass, climbing steep slopes, dropping into rocky ravines, beyond which fresh ridges separated by fresh ravines rose in endless succession. At last on the 21st, very early in the morning, we came out into the wide flat valley of Miski, where we made a brief halt to allow the stragglers to come in. All our camels were there except one, and I may say that I felt much satisfaction at having succeeded in bringing them back to the starting-point after this toilsome flying expedition of more than 300 miles, carried out in seventeen days in the unknown and exceptionally difficult mountain region of which I have tried to give you as closely exact a description as I can.