t must have taken us an hour to reach the bottom. I did not count the steps, but it must have been at least a thousand feet. The air grew rapidly warmer as we descended. We both took off most of our heavy fur garments, and left them hanging on the rungs.

I was rather nervous. I felt the nearness of an intelligent, hostile power. I had a great fear that the owners of those steps would use them to find us, and then crush us ruthlessly as they had brought down Meriden's plane.

The little square of white light below grew larger. Finally I saw Ray swing off and stand on his feet in a flood of white radiance below me. The air was warm, moist, laden with a subtle unfamiliar fragrance that suggested growing things. Then I stood beside Ray.

We stood on the bare stone floor of a huge cavern. It must have been of volcanic origin. The walls glistened with the sparkling smoothness of volcanic glass. It was a huge space. The black roof was a hundred feet high, or more; the cave was some hundreds of feet wide. And it sloped away from us into dim distance as though leading into huger cavities below.

The light that shone upon us came from an amazing thing—a fall of liquid fire. From the roof plunged a sheer torrent of white brilliantly luminous fluid, falling a hundred feet into a shimmering pool of moon-flame. Shining opalescent mists swirled about it, and the ceaseless roar of it filled the cave with sound. It seemed that a stream of the phosphorescent stuff ran off down the cave from the pool, to light the lower caverns.

"Very clever!" said Ray. "They make the stuff up there at the cone and run it in here to see by."

"This warm air feels mighty good," I remarked, pulling off another garment.

Ray sniffed the air. "A curious odor. Smells like something growing. Where anything is growing there ought to be something to eat. Let's see what we can find."

Only black obsidian covered the floor about us. Cautiously we skirted the overflowing pool of white fire, and followed down the stream of it that flowed toward the inner cavern. We had gone but a few hundred yards when suddenly Ray stopped me with a hand on my arm.