sounds high up in the sky as of the clash of arms or of musical martial instruments. If travellers fall to the rear or get separated from the caravan, they hear themselves called by name. If they go after the voice that summons them, they lose themselves in the desert. Sometimes they hear the tramp of horses, and taking it for that of their caravan, are drawn away, and wander from the right course and become hopelessly lost. The old Venetian traveller Marco Polo mentions these mysterious sounds, and says that they are produced by the spirits that haunt the desert. They are, however, otherwise explicable. On a vast plain the ear loses the faculty of judging direction and distance of sounds; it fails to possess, so to speak, acoustic perspective. When a man has dropped away from the caravan, his comrades call to him; but he cannot distinguish the direction whence their voices come, and he goes astray after them.
Rubruquis, whom Louis IX. sent in 1253 to the court of Mongu-Khan, the Mongol chief, says that in the Altai Mountains, that fringe the desert of Gobi, demons try to lure travellers astray. As he was riding among them one evening with his Mongol guide, he was exhorted by the latter to pray, because otherwise mishaps might occur through the demons that haunted the mountains luring them out of the right road.
Morier, the Persian traveller, at the beginning of this century speaks of the salt desert near Khom. On it, he says, travellers are led astray by the cry of the goblin Ghul, who, when he has enticed them from the road, rends them with his claws. Russian
