"'It don't sound any too good, I'll admit that,' Sands acknowledged. 'It might be wind caused by an underground suction, or chlorine gas blowing out of a volcanic fissure. The stink smells like chlorine gas.' "We peered into the darkness trying to penetrate a solid wall of unfathomable black. My eyes ached under the strain. I removed my hand from Sands' arm to rub them. "Suddenly a darting light passed like a meteor through the blackness above, showering green, luminous sparks to the floor of the cave! In the brilliant light I caught sight of Sands' features. The expression on his face told me that he had barely missed being struck by the glaring missile. He yelled loudly to drop down flat, as another light in the form of a sphere apparently of molten metal, darted over us, dropping a shower of floating sparks. "Instantly the meteor-like ball was followed by other bright, swift-moving lights which passed perilously close to us and raced to the end of the tunnel toward the entrance. Their passing was marked by a low, droning hum of a likeness to the drone of the big sphere that had been shot from the whirling column in the center of the pool. "Lying flat on our backs on the hard lava floor of the cavern back there under the terrible Manalava Plains, Sands and I watched the space above us. Closer and closer came a steady stream of brilliant lights that permeated the already nauseating air with the odor of burning carbon! I raised my gun several times to fire at one of the lights but thought better of it until I was sure of hitting the mark. Meanwhile I began to think what might happen should I actually succeed in striking one of them. I asked Sands' advice. He suggested that I try my luck. "I raise my head a little to look down into the tunnel. Issuing from what appeared to be a deep hole perhaps a half mile ahead, came a spinning ball of glaring fire. It hovered for an instant over the yawning, luminous hole and then darted in our direction at a terrific speed. I lifted my gun from my hip. When the light was near enough, I pulled the trigger. "The sharpness of the concussion filled me with fear, but in the instant the light was gone. Only a shower of sparks remained to prove that my slug had gone true. The sparks lay on the tunnel floor, glowing like lumps of molten copper, green and red. "We lay on the ground for several minutes more. Then I nudged Sands. We walked along the path for perhaps a dozen feet and then I realized that our sense of direction was gone altogether. We were completely lost in a strange world of blackness pierced only by mysterious lights and sounds, of whose origin I could not guess. "Presently we realized that it was folly to wander around when any step might precipitate us into unknown dangers. I had an unpleasant feeling of helpless fear that was gradually overcoming my reasoning powers again.