This, indeed, I discovered to be the case. We had now reached the industrial center of Atlantis; and all the rest of that day we were busy inspecting manufacturing plants of sundry kinds and sizes. But nowhere was the air clouded with that smoke and dust which I had come to associate with industrial districts in my own land; nowhere was there a dingy or soot-blackened building, nowhere were my ears assaulted by the shrieking or droning of whistles, or by the hammering, pounding, screeching, whirring or grating of machines. Instead, we passed through a region that might have been recommended to sufferers from nervous ailments. In the midst of pleasant, grassy lands an occasional tree-bordered building arose with glittering steeples or stainless marble facade or august columns of granite; and within each building, which one might have mistaken for a mansion or a temple, electrically driven wheels and levers would be operating noiselessly, preparing the food of the Atlanteans or weaving their clothes from the fibre of a flax-like plant, manufacturing farm implements or fertilizers or scientific articles or household wares; and in each of these factories a few workers (never more than a score) would be calmly and often smilingly tending the machines, occupying thus their two or three hours of assigned daily service for the State. * * * * * The institution that interested me most was the building where chemists were at work renewing the air supply of Atlantis--or, rather, the oxygen supply. Here, in a long hall dominated by great vats connected by pipes and wires reminding me vaguely of the distillery, a continual stream of water was being disintegrated by a process of electrolysis, the hydrogen being diverted to enter into various chemical compounds, with carbon nitrogen and other elements, the oxygen being released into the atmosphere to replace that consumed by respiration and combustion. By means of the air-gauge, a finely adjusted apparatus whose index was a flame that varied in intensity with the amount of oxygen, chemists were able to determine how much of this vital gas was required at any specific time; but some oxygen had to be provided continually, for, large as Atlantis was, it was not so great that nature would preserve a balance and replace the oxygen that was consumed by that freed in the course of organic processes of plant life.