ahead. Before the caravan stretched level ground at the borders of which the keen eyes of the Arabs again espied a cloud. It was higher than the previous one and, besides this, there shot from it what seemed like pillars, or gigantic chimneys expanding at the top. At this sight the hearts of the Arabs and Bedouins quailed for they recognized the great sandy whirlpools. Idris raised his hands and drawing his palms towards his ears began to prostrate himself to the approaching whirlwind. His faith in one God evidently did not prevent his worship and fear of others for Stas distinctly heard him say:
"Lord! We are thy children; therefore do not devour us."
But the "lord" just dashed at them and assailed the camels with a force so terrible that they almost fell to the ground. The animals now formed a compact pack with heads turned to the center towards each other. Whole masses of sand were stirred. The caravan was enveloped by a dusk deeper than before and in that dusk there flew beside the riders dark and indistinct objects, as though gigantic birds or camels were dispersed with the hurricane. Fear seized the Arabs, to whom it seemed that these were the spirits of animals and men who had perished under the sands. Amid the roar and howling could be heard strange voices similar to sobs, to laughter, to cries for help. But these were delusions. The caravan was threatened by real danger, a hundredfold greater. The Sudânese well knew that if any one of the great whirlpools, forming incessantly in the bosom of the hurricane, should catch them in its whirls, it would hurl the riders to the ground and disperse the camels, and if it should break and fall upon them then in the twinkling of an eye an immense sandy mound would cover them in which they would remain until the next
