They passed the lonely buttes, the parched beds of lakes, salt-coated. Still they saw not a living thing; still the city seemed to recede with the horizon, its sharp beautiful outlines unchanged. For some time the horses had been trotting unevenly. Gradually they relaxed into a dogged amble, their heads down, their tongues out. Every now and again they half paused, with quivering knees. Adan's was the first to collapse; it fell to its knees, then rolled over, Adan scrambling from under, unhurt. Roldan also dismounted, and both boys, without a word, unsaddled the poor brutes, thrust the pistols into their belts and what was left of the provisions into their pockets. They cast off their ponchos, then once more turned their faces to the south. But they did not advance. They stood with distended eyes and suspended breath. The city had disappeared. Adan was the first to find speech. "A fog?" he asked. "A rain storm?" "There is neither. The horizon is as blue and clear as it is on the north and east and west. It is a miracle. Let me think a moment." He sat down and took his head between his hands. After a while he looked up. "For hours I have been trying to remember something," he said. "Do you remember what that mayor domo said to us?--Keep straight on, straight on, never turning to the left, for that way lies the terrible Mojave desert, I barely heard his last words at the time; that is the reason I have had such a time remembering. We are in the Mojave desert, my friend." Adan, whose mouth was still wide open, sat down and rolled his eyes from east to west. "Caramba!" he ejaculated finally. "I could say a good deal more than Caramba. All that I have heard of this Mojave comes back to me. There is no water on it, no living thing but half choked cacti and stunted palms. Men who are lost on it go mad and die of thirst--" "Ay, yi, yi!" "Si, senor. However, it might be much worse. It is winter, not summer,--when the heat kills in a day; we have food and a little wine; we are young and very strong; we have not come so many leagues that we cannot walk back. And we have each other. Think, were we alone!" "Yes, it might be worse," said Adan, "but all the same it might be six or eight leagues to the northwest better. And that city? What was it? Where has it gone?" "I do not know." Privately he believed that it had been a glimpse of heaven, and was disturbed lest it might have been a portent of death. But his mind was too active, his nature too independent to sit down under superstition. If he died on the desert, it would not be through lack of effort to get out of it. He stood up, setting his lips. "Come," he said. "We gain nothing by sitting here, and we are both fresh; we can walk many leagues before night." "Do you know which way to go?" asked Adan.