"So ages passed, and might have continued so to pass until the end of time, had not necessity pressed once more upon the lizard-people in their cavern world. As I have said, the interior fires of earth's heart had pressed up close against the walls of their cavern, bursting forth in one place in that fall of flame which lighted their world; and now the molten fires began to press with more and more force against the walls, forced up by convulsions far beneath, and it was only a question of time until they would burst through those walls and sweep over all the cavern world in a great cataclysm of annihilating fire, instantly wiping out all life in the cavern. They must leave it, they knew, before that happened, so they decided to venture back once more to earth's surface. So they again placed the great disk-platform in position, and as it again swept ceaselessly up and down a party of them rose on it and opened the mouth of the shaft, in the swamp far above. It was that party, exploring the swamp on their great brontosaurs, who had captured me, and brought me down here to examine me. They had observed that intelligent creatures, men, now were established on earth's surface, that one of their cities stood near the swamp itself, and so they planned to send up first a striking force which would annihilate that city, annihilate Brinton, to prevent any possible interference from it. Then that first attacking force would return down the shaft, leaving guards at its mouth, and all the lizard-people and their dinosaur hordes would gather and assemble to pour up the shaft on the great disk and sweep out upon earth to conquer and annihilate the world we know. Besides their dinosaurs they had their own heat-beam projectors, those white globes in which they could condense and concentrate heat-vibrations, holding those vibrations static and releasing them at will in a concentrated ray. "So they poured up the shaft to attack Brinton, and now that that attack has been made, their first striking force will return down here, gathering together all their hordes for the last attack on earth itself. Within hours, I think, that attack will take place, their hordes will swarm up the shaft and out over earth. Up at the shaft's mouth they have placed a great switch which will be turned on when all of them have left this cavern and are safely above, and which will release concentrated rays down here that will blast the cavern's walls and allow the floods of fire that press against them to burst into the cavern. For they fear that if they do not do so the imprisoned fires will burst forth in some mighty cataclysm that will wreck all earth. To loose the fires upon the cavern while they are in it would be to annihilate themselves, of course, but if it is done through the switch above after all of them have gained earth's surface there will be no harm to themselves.