“Stand back,” he ordered gruffly. “It is the heat; let me alone!” The American sank into his seat. The heat became more and more intense. Both men were purple in the face, and the perspiration was rolling from their bodies in streams. Down sank the machine. “I can't manage it,” said Branasko hoarsely, “we'd as well give up.” Just then Johnston noticed the mouth of a cave behind Branasko. “Look,” he cried, “can't we get into it?” Branasko looked over his shoulder, and, as he saw the cave, he uttered a glad cry. He quickly turned the wheel and drew out a lever at his right. The machine obeyed instantly; it swerved round suddenly and dived into the cave. The cool air soon revived them, and Branasko had little trouble in bringing the car to a resting-place on the rocky floor of the cave. Before them hung impenetrable darkness, behind a curtain of red light. “We are in a pretty pickle now,” said Johnston despondently, as they alighted from the car. “Nothing to do but to make the best of it,” sighed Branasko. “Perhaps this cave may lead out into some place of safety.” Johnston's eyes had become somewhat accustomed to the gloom, and he began to peer into the darkness. “I see a light,” he exclaimed; “it cannot be a reflection from the fire in the pit, for it is whiter.” The Alphian gazed at it steadily for a moment, then he said decidedly: “We must go and see what it is.” Without another word he started toward the white, star-like spot, sliding his hand over the rocky wall, and springing over a fissure in the floor. Gradually the light grew brighter, till, as they suddenly rounded a cliff, a grand sight burst upon their view. They found themselves in a vast dome-shaped cavern, thousands of yards in diameter and height. And almost in the centre of the floor, from a red and purple mound of cooling lava, leapt a white stream of molten matter from the floor to the dome. And in the black dome, where the lava turned to molten spray, hung countless stalactites of every color known to the artistic eye. And from the foot of the fountain ran a tortuous rivulet that lighted the walls and roof of a narrow chamber that extended for miles down toward the bowels of the earth. Branasko was delighted. “The king does not know of this,” he declared, “else he would make it accessible to his people, and call it one of the wonders of Alpha. By accidentally sinking into the pit we have discovered it. But,” he concluded, “we must at once try to find some way out other than that by which we came.” They turned from the beautiful fountain, and, holding to each other's hands, and aided by the light behind them, they stumbled laboriously through the semi-darkness. Branasko's ears were very acute. He paused to listen. “Hark ye!” he cautioned. The combined roar of the pit and the fountain of lava had sunk to a low murmur, but ahead of them they now heard a rushing sound like a distant tornado.