"Hum-m!" Dr. Kirshner looked disappointed. "That seems to want to spoil my plans for this afternoon." "How's that?" "I had intended to do a little exploring up on top of that wall of stone." There were exclamations of surprise and anxiety. "What!" cried Mr. Lewis. "Why, you couldn't scale that steep cliff with ladders and ropes!" "Maybe not in some places," the archæologist smiled. "But I have noticed that there are large fissures that would offer footholds with comparative ease, and I'm going to chance it. There's no telling what I may bring to light from up on that lofty rock." There was a period of silence, finally broken by Bob. "May Joe and I go with you?" he asked. There were loud protests from the youths' fathers, who thought it almost madness to attempt to climb the steep slope. But Dr. Kirshner held up a hand for silence. "Wait till we finish this meal and I'll show you a place where it will be more or less easy to get to the top," he said. "If it's there, I'd like to see it," came from Mr. Holton. When the noon meal was over, the archæologist led them to a point perhaps a quarter of a mile from the camp. He pointed up and smiled. "Doesn't that look like an easy climb?" he asked. "Plenty of safe footholds and cracks to grasp. I'm going up." Bob and Joe put in a request to their fathers to accompany the scientist and were finally given permission. "But be careful," warned Mr. Lewis. "And don't wander too far away." Dr. Kirshner led the way up the side of the cliff, followed by Joe and Bob. The climb was in some places difficult and a little dangerous, but they plodded surely up. At last, panting and perspiring, they came to the last foothold and pulled themselves up to the top. Then they turned to take in the view below. Cries of astonishment came from all at the wonderful panorama that stretched out before them. Hundreds of feet down and to their right was the camp, and a short distance away were Mr. Holton and Mr. Lewis. The dromedaries were tethered beside a large rock near the cliff. "I suppose Fekmah and Tishmak are in the tent," remarked the scientist, scanning the landscape. With the aid of his powerful binoculars the camp was made to appear quite near, and the features of the naturalists were easily made out. At last Dr. Kirshner turned about. "A fine view," he said. "But let us not spend too much time here. I want to explore the roof of this cliff." The rocky surface was in most places flat, but there were a few huge fissures that apparently extended far into the rock. They had come to one unusually deep crack when Dr. Kirshner stopped and slid down the steep side, desirous of seeing the unusual. He reached the bottom some fifteen feet below, sending a score of small rocks down the side of the crevice. "What's there?" Joe called down, bending over the side. "Nothing, I guess. There is---- Wait a minute!"