The spot of light grew stronger, larger, as we climbed down toward it, until finally we saw that we were nearing the shaft's bottom, at which it gleamed. A few minutes more and we had clambered down the last peg and stood at the bottom of the shaft, a dark, circular well of metal pierced in one side by a doorway through which came the dim white light. Then we were bunched together once more between our guards, and were marched through the door into a long corridor dimly lit by a few globes of lambent white light suspended from its ceiling. As we marched along this long, metal-walled corridor I wondered how far beneath the great pit's floor we were, estimating by the length of our downward climb that it must be thousands of feet, at least. Then my thoughts shifted as there came from ahead a deep humming, beating sound, and a gleam of stronger light. Before us now lay the end of the corridor, a square of brilliant white light toward which we were marching. We reached it, were passing through it, and then we halted in our tracks in sheer, stunned astonishment. For before us there stretched a vast open space, or cavern, of gigantic dimensions, its floor and sides and ceiling of smooth black metal, brilliantly illuminated by scores of the lambent globes of light. For thousands of feet before and above us stretched the great space, and in it was a scene of clamorous activity that was stunning after the darkness and silence through which we had come. Ranged on the mighty cavern's floor were long rows of machines the purposes of which were beyond our speculation, incredibly intricate masses of great arms and cogs and eccentric wheels all working smoothly with a steady beat-beat-beat of power, and tended by countless numbers of the formless nebula-creatures among them. Some seemed to be ventilating-machines of a sort, with great tubes leading upward through the cavern's ceiling; from others streams of white-hot metal gushed out into molds, cooling instantly into wheels and squares and bars; still others appeared to be connected with the great globes of light above; and some there were, like great domed turtles of metal, that moved here and there about the cavern's floor, reaching forth great pincer-arms to grip stacks of bars and plates and carry them from place to place.