"Some foothills! They must rise all of 25,000 feet from the valley floor," decided the aviator, "and I should imagine this valley is a good mile below sea level. Yes! That must be it: this nightmare country lies in a huge geographical fault--something like the Dead Sea." * * * * * Mile after mile he could see fertile green land stretching away toward some low undulating hills on the horizon. Atlans was very thickly settled--that he recognized at once--for the terrain was divided and sub-divided into a vast checker-board, such as he had seen in France and Germany, while terraces, green with produce, had been laboriously gouged out of the frowning mountain sides. Then his eye encountered the source of that curious amber light which pervaded the whole valley. A titanic flaming gas vent spouted like a cyclopean torch from the peak of a nearby mountain. Its steady, subdued roar struck Nelson's ear as he turned away his eyes, for the glare was too intense to be long endured. Further down the valley were two more such incandescent vents, shooting their flaming tongues boldly into the sky, warming the air and casting that rich, amber radiance over all. "That is Mount Ossa nearest us," the Atlantean's voice came as though from a long distance. Victor Nelson was too staggered, too unspeakably amazed to register the fact of the Hero's proximity. "Below are Pelion and Jilboa, which, with Jabor, the greatest of all the flames, illuminate and warm the valley." Nelson's eye, trained to be all observant, ranged far and wide, noting the presence of many lacy, frothing geysers which spouted at varying intervals. There were, also, many steaming ponds and waterfalls which sprang in smoky confusion from the rock palisades to either side. * * * * * Nearer at hand he could distinguish a number of huge stone structures, evidently forts and public buildings. Strategically placed all about were more of those terrible brass retortii, gleaming dully under the incandescent glare of the flame sun. "Come," cried Hero Giles with an impatient gesture of his hand, "we must e'en hasten to the tube-road terminal. Word has long since been sent to Heliopolis of thy arrival."