"Naturally, however, an intensely powerful gale of heated air roared up from this molten lake, and by setting a ring of current-projectors around the lake they were able to concentrate the cyclonic power of those winds into a single concentrated air-current roaring straight up and through the shaft, and capable of lifting titanic weights up that shaft, just as a cyclone, which is concentrated wind, will lift and whirl about great buildings. And this terrific, upward-thrusting current they used to lift their great disk-platform up the shaft, arranging the projectors beneath so that the force of the current automatically lessened when the disk reached the top, and allowed it to sink again to the cavern's floor, to the fiery lake, whence it traveled up again, and so on ceaselessly, an automatic, never-stopping lift or platform on which the throngs of the lizard-people and their dinosaur-beasts were able to move down into this cavern world. "Only a portion of their dinosaur servants did they bring with them, leaving the rest to perish above, whose bones, indeed, I had found in the swamp. When this had been done they closed tightly the opening of the great shaft, above, and dismantled the great ascending and descending disk for which they no longer had need. Then their hordes set to work to build up their cities anew in their new cavern home. Far above them the surface of earth writhed and twisted gigantically, annihilating all the hordes of dinosaurs above, but the cavern world of the lizard-men remained unchanged, as they had foreseen, and in it they lived serenely on. * * * * * "When at last the surface of earth quieted once more they could have quitted their underworld and gone back up, but they did not do so, since by then their city was established in the safe, warm world of the mighty cavern and they had no desire to leave it. So in that cavern they lived on, while on the world above the races of mammals rose to replace the great reptiles; until with the passing of ages man rose to dominance over all those races and set his cities where those of the lizard-men had once stood. The mouth of the shaft was hidden and covered by the great swamp, and on all earth none suspected the races who dwelt beneath them.