Five days' monotonous journeying across the sandy plains, and then five nights of travelling, with the days devoted to rest, had passed before the river was approached at a bend which brought it near the line of travel which the Sheikh had traced out for himself by the stars. The way had been marked by the bones of camels, and in two places other bones scattered here and there told their horrible tale of suffering or attack, one skull displaying a frightful fracture that was unmistakable; fountain after fountain had been reached, and refreshing halts had been made where the waters gushed from some patch of rocks, to fertilise a small extent around, supporting a few palms and prickly, stunted bushes of acacia-like growth, before they started away again into the sand; and in cases where the next water-hole was too far, one, two, or three camels bore away water-skins well filled, to carry the party over the next halting-place. The necessity of keeping up the supply forced their guide to adopt a zigzag mode of progression, and to make his little caravan traverse nearly double the distance that would have been necessary could they have taken a bee-line towards the south. But experience had taught all travellers who journey by the desert, instead of by the great waterway with its vast cataracts, where the pressure of the earth forced the water springs to the surface, and naturally these were the goals for which all tired travellers made. There were but few incidents during a fortnight's travel, and more than once Frank's heart sank as he pondered upon the little advance they had made; but as the professor said, they were two weeks nearer their journey's end, and all was well. But it was sadly monotonous. The morning and evening skies were glorious, but their beauties soon began to pale, while on the hot days the journeys were most exhausting, and the travellers welcomed the clear nights when the stars blazed on high, for these were the times the Sheikh selected for progressing. "There is no fear then of going far astray," he said; for he knew nothing of the use of the compass, and the adventurers had never thought of bringing such an aid. In company with the doctor and professor such natural history objects as presented themselves were examined--lizards among the rocks, a few snakes, harmless, and the poison-bearing cobra; but away from the river, birds were rare, save those of prey, and as to animals they were heard more than seen. A gazelle or two, little and graceful, bounded across the track, but it was at night that the howling of the jackals and the long, hideous snarling of hyaenas taught the travellers that there were plenty of these loathsome creatures hungrily waiting for the weaklings of such caravans as crossed the sandy plains.