Tishmak had a moment before left for the house. Now he returned with a thin, lithe Arab, who was evidently the owner of the camels. A short conference between Fekmah and the stranger took place. Then Fekmah turned to the Americans. "We can have the dromedaries," he said. "And he is asking only a fair amount. Come and I will pick them out." The others followed him over the field, where he singled out twenty of the best-looking beasts. "Now," said Mr. Holton, "we want to practise riding before we start on the real journey. Perhaps we'd better do that this afternoon. Then we can load up in the evening and get started in the morning." Fekmah nodded. "We'll go now and come back this afternoon," he said. Shortly after the noon meal the explorers left the hotel, intent upon trying their skill astride the ponderous humps. None of them but Fekmah had ever had the experience of riding on camelback. "Wonder how it'll be?" mused Joe. He soon saw. Aside from a most uncomfortable jerking it was a novel and enjoyable experience, for the time being, at least, surpassing horseback-riding. "But you'll soon get tired of it," said Mr. Holton. "At least Fekmah says so." "Dad might say we'll get fed up on it," remarked Bob, when they were ready to start back to the hotel. "But I haven't yet." "Nor I," put in Joe. "But of course, after several days----" There was much to be looked after that evening, and it kept the explorers busy. Tishmak acted as leader in securing the food supply, which, however, was also to include canned goods. The naturalists and Dr. Kirshner attended to last-minute preparations, while the youths kept their time busy in helping the others. Early that night they retired, eager to get all the rest possible. "Sleep well," said Mr. Lewis, as the boys jumped in bed. "We'll have it rough from tomorrow on." At four o'clock the next morning Bob and Joe were awakened by Mr. Lewis, and despite the fact that they were still very sleepy, they began the task of getting their belongings together. It took them the better part of an hour, although they worked like beavers. "We're ready to leave, boys, if you are," called Dr. Kirshner, opening the door to their room. "The provisions are on the dromedaries, and Tishmak is ready." The youths' hearts were in their mouths. Leave! Leave for the great Sahara Desert, with its mysteries and thrills and tragedies! They could hardly come to a full realization of the true situation. "It'll be great, Joe, old boy," said Bob, deeply touched. "At the end of this expedition we'll be full-fledged adventurers." The youths went down to the hotel lobby and found their fathers, Dr. Kirshner, and Fekmah. Tishmak, the newly engaged guide, had left for the camels, which he promised to have in readiness.