Seeking coolness in the shadow of a great boulder on the rampart of this crater, Sana sat down, her baby in her arms, while Carl stood nearby studying the wonderful formations of rock and lava at every hand. Suddenly the air was filled with a great roaring sound, a sound so terrific that it was deafening. A light, brighter than that of a hundred suns, illumined the earth. With a rush the realization was upon them. The comet was fast approaching the earth--the end of the world was at hand. Then the collision--the earth shook under the impact--the air was filled with dust and smoke. Fearful for the safety of his beloved ones, Carl sprang to them, to clutch them tightly in his arms. Then darkness! * * * * * Someone laughing? Carl opened his eyes. Of course they were laughing at him, lying at the feet of his camel, from whose back he had fallen in his sleep, with his arms tightly hugging the camel’s legs. CHAPTER XI UNDER THE KNIFE Carl, endeavoring to get to his feet, was aware of a severe pain in his side. His left foot, too, pained him and was unable to support any weight. Struggling at last to an upright position, he staggered forward a few steps, only to lurch head first into the burning desert sand. Immediately the other tourists were off their camels and at his side. A hasty examination proved that his left ankle was badly broken and that, from all appearances, he had suffered internal injuries in his fall from the camel. Everything possible was done to relieve his pain and make him as comfortable as possible. With great care he was literally hoisted aboard one of the camels, and strapped on its back, where he was held secure from a further fall by one of the guides who rode behind him. The place of Carl’s accident was near the Wadi Draa River, flowing past the southern end of the Atlas Mountains, so they were still some two hundred and fifty miles, about four days’ ride from Mogador, the terminus of the caravan. Accordingly the caravan headed for the nearest town, Glisscim, but here they found only a native doctor, to whose care none was willing to entrust the sick man. Securing an automobile, the only one to be had and a ramshackle bouncing affair at that, Carl was driven to Mogador. Here, too, disappointment was in store for him. Suffering although he was from the pain in his side and ankle, Carl would not consent to gamble his chances on the more or less speculative knowledge of the only doctor in that locality.