"Suits me," agreed Joe. "I feel like I could sleep for two or three days." "One of us had better stand guard, though," said Mr. Lewis. "That bandit caravan might return unexpectedly." "I'll do it," volunteered Dr. Kirshner. "I'm not sleepy. I'll just take it easy here and read." For the next three hours Bob and Joe slept soundly, forgetting that they were under a scorching desert sun. They were not tired, but were extremely drowsy from the heat. Then suddenly they were awakened with a start. They looked about wonderingly. Dr. Kirshner stood over them, holding his rifle in readiness. "The bandits!" he exclaimed excitedly. "I believe they're coming!" Mr. Holton and Mr. Lewis jumped to their feet and grabbed their guns. Cautiously they peered out, holding the flap but a few inches up. "Where are they?" demanded Bob's father, while Tishmak and Fekmah ran forward. "I'm not sure that it's they," the archæologist said. "But I heard camel steps a moment ago, and in this country it is best to investigate before it's too late." A second later Tishmak stopped still and listened. He held up a hand for silence. Fekmah had also caught a sound. "It's they," he whispered. "Camels! They're coming this way!" The swishing sound increased, and Dr. Kirshner called his friends together for a plan of defense. "Chances are those bandits were planning on surprising us while we slept," he said quietly. "They figured that the time to get the camels they wanted was during our afternoon siesta. But it apparently didn't occur to them that we would set a guard. "Now the thing for us to do is get together and give them a real welcome with bullets. They'll probably come around the back of the oasis, where our dromedaries are grazing. We'll go around there and hide beside that sand dune. Then when the robbers--and I think that's who the newcomers are--come, we'll fire a volley of bullets into the air. If we find we can't frighten them away, we'll shoot their camels from under them. Then if that fails, we'll have to shoot the men." The others thought this good advice. "We must act cautiously, though," warned Mr. Lewis, as they made their way to the back of the oasis. When they came to the dune, they crouched down and waited. Tishmak glanced around the corner. A moment later he drew back, his face scowling. He mumbled quietly to Fekmah. "They're coming," the latter said. "And they are the robbers." The swishing of footsteps grew louder, indicating that the Arabs were coming nearer. "Now!" said Mr. Lewis. "Fire in line, aiming at the sky. Then we'll see what happens." Seven rifles spoke up in rapid succession, a dense cloud of smoke arising. That the robbers had been totally surprised was certain, for a loud chattering followed. Then the sand was thrown up, and they rode off at lightning speed. Joe peeped around the corner of the dune.