Compartments we found in which were structures that puzzled us as completely as had the tiers of shelf-openings. These structures were great flat metal containers, each scores of feet in length and width but hardly more than a foot or two in depth. They were ranged one above the other in great supporting frameworks, and each container was filled with black fine soil. The compartments that held these had set in their walls great white disks which were connected to intricate apparatus that seemed generators of some kind of force, but more than that we could not ascertain from our inspection of them. The whole arrangement, the great shallow containers of soil, the disks in the walls, the generators connected to them--all was utterly enigmatic and perplexing to us, and we were forced to give up the riddles and pass on into other compartments, in which were other things almost as mysterious. Some held giant globes of burnished metal, now dust-covered, which occupied almost a whole compartment each. These great gleaming globes were among the most puzzling things we had found, since there was, in the compartment of each one, no other object or indication of their purpose, save for a few switches mounted upon a panel, the combination of which we could not discover, opening and closing them in vain. We had seen these great globes from above, dotting the vast compartment-city here and there in great numbers, but we could learn no more of their purpose standing there beside them than we had been able to guess from above. And near these there were strange looming machines, many-cogged and with a great hopper above whose purpose we guessed, at least, guessing that these were the mechanisms that produced from some raw materials the artificial diamond-hard black stone-material that made up all the intersecting walls of this strange huge city-world. Each of these machines had before it a very low, round metal seat, with in front of that seat the controls of the machine, a half-dozen burnished metal levers. As we saw them Marlin and I exchanged startled glances. Had the being who operated that machine, who sat before it, held and operated _all_ those control-levers of the mechanism? Back to our minds flashed the strange low openings of the doors through which we had come, and for a moment the same strange sense of dread chilled me. But I shook off the feeling, followed Marlin on into another compartment, glancing back through to where our space-flier poised in the air now far across the city behind us.