"We'll need more than coats at night, if what Dr. Kirshner said is true," said Joe. "Gets cold as Greenland's icy mountains." "Seems strange, doesn't it?" "Yes. But you remember it was the same way in Brazil. And that's about as hot a country as there is anywhere." Soon the flat hill of Gara Krima, dominating the sandy plain, could be seen, its smooth surface tinted with many colors. Then it was left behind, and the explorers came to a region of loose sand. The dromedaries found it more difficult to plod through, and slackened their rapid pace somewhat. Although their feet were specially adapted for traveling on sand, they made much better time on hard surfaces. "Look at the dust they're making," observed Bob, as a dense cloud of fine sand particles arose, making it necessary for the youths to ride a short distance to one side of the pack animals. "They don't believe in kicking it up, do they?" Joe said dryly. After a while the sun came out in full splendor, sending its dazzling rays down on the scorched sand. Bob and Joe soon perspired freely, and were glad to remove their coats. "Whew!" gasped Joe. "I'd give anything for a drink of water." "So would I," his friend replied. "I'm going to ride on up and ask for one." "Remember me while you're there." It was a good distance to the other end of the caravan, but the sure-footed dromedary trotted along briskly. Fekmah waved as Bob passed. "How about a drink of water, Dad?" asked Bob, coming up to his father's camel. "Go to it," was the answer. "We'll come to a well before long, and refill the canteens." The third and fourth animals back were the water carriers, and Bob lost no time in filling his container. Then he drank freely of the refreshing liquid, and felt new life creep into him. Although warm, the water did wonders in quenching his thirst. Again he filled the container and rode back to his friend, who was delighted. "I was afraid they wouldn't let you have it," Joe said, wiping the perspiration from his brow. "Wouldn't have, only there's a well not far away, and we'll have a chance to refill the tanks." "Well, huh? Wonder if they're this close together all along?" "Let's hope so." A little later the explorers passed a scattering of bones and skeletons that were partly covered with sand. They were dry from age, having probably been uncovered by a sandstorm. "Camels' bones, I suppose," remarked Joe. "They've become overcome with thirst, most likely." "Who knows but that the skeletons of their riders are there some place, too," said Bob, his face sober. The sight was not a pleasant one, for it brought to mind the fact that it was altogether too possible that their little caravan might perish for want of water also. Some time elapsed before the boys resumed their cheerful mood. As they traveled on, the ground became strewn with small red pebbles that shone brightly in the dazzling sunlight.