"It is that!" came the excited reply. "An ancient Libyan record, perhaps of a noteworthy event that took place in this vicinity. If you will give me a few minutes I'll copy this down. It may prove of great interest in my future study of early Sahara peoples." The others waited for the archæologist to transcribe the writing. It proved very difficult to read offhand, but that a full translation would eventually come to light was not in the least doubted by the other Americans. In fact they had come to regard Dr. Kirshner as a wonder among men of his profession. At last he put the paper back in its place and made a sign to Tishmak that he was ready to continue the journey. "Now let's make time," said Bob anxiously. "We ought to get over a good many more miles before time for the noon rest." And they did. The country had not yet become rough enough to hinder the progress of the dromedaries, even though huge boulders were strewn about. By ten o'clock they had reached the base of the Plateau of the Mouydir, a thousand-foot-high wall of solid stone. "Tuaregs have many superstitious legends about this rock," said Fekmah, after talking several minutes with Tishmak. "They believe evil spirits up in great caves come down and kill travelers. They too think sandstorms and whirlwinds are caused by spirits hiding up in large cracks there." "How interesting," said Dr. Kirshner, getting out his small portable typewriter. Bob and Joe had taken motion pictures along the journey, and now they saw another opportunity to film a scenic wonder. "I'd like for you to do a little acting," said Bob to Fekmah, as the youth turned his camera in the direction of the mammoth wall of rock. The Arab looked up in some surprise. "I want you to point to the Plateau of Mouydir and talk to Dr. Kirshner," the young man explained. "Tell him about the legend of the Tuaregs. Meanwhile I'll be photographing you. Too bad this can't be a talking picture. All right. Let's go." Fekmah understood and smiled. Dr. Kirshner was also willing to assist the young photographers in their work. The Arab and the American engaged in conversation, while Bob took movies of them pointing to the high rock. When it was finished, Bob and Joe smiled in satisfaction. "That's the kind of scenes we ought to have more of," Joe said. "They're different from the usual monotony of 'shooting' the country alone." "Gives a sort of individuality, huh?" laughed Mr. Holton. "Well, any time we can be of use to you, let us know." Camp was made at the very base of the huge rock. Then the usual meal was prepared. "Use water sparingly," cautioned Mr. Lewis, as they sat down on the cool sand in the shade of the tent. "Tishmak says we will not come to another well till tomorrow afternoon." "That's a long time to wait," said Dr. Kirshner gravely. "Can we make what we have hold out?" "We've got to," Joe's father returned. "We'll have to restrain from taking any undue exercise in the heat of the sun."