Where the sand--pure ferrous oxide--struck the beam, I could not look without daring blindness, so violent were those disruptive reactions. But just above it, a silvery cloud arose and dissipated itself; the freed oxygen, enriching the atmosphere in this gigantic crater that was Marsport. And below it, a cataract of burning metal sprayed downward into an enormous vat, the sides of which were spouting a continual flow of this dangerous liquid into troughs which spread out in a fanlike pattern that must have encompassed the entire city. It took me a few minutes of thought, but I figured it out, as I drew back through the window from the heat. It was not enough that the converters could supply the citizenry with breathable air. The planetary temperature at night was below the level at which a man could live, save with the most cumbersome, demanding precautions, such as are demanded by arctic exploration on Earth. And so, instead of merely letting the metal cool into ingots before it was shipped where it was needed, it was channeled through the city, passing behind all the buildings where alleys would normally be, and warming the environment so that going into the night air would not mean sure death by freezing. I could not see the far end of the trough, but I knew that beyond the city limits the troughs would converge, and iron would be cooled, shaped and shipped. It was ingenious, and something I'd never run across in my readings about Mars. But then, I was never much of a space exploration fan. However, ingenious or not, it was a crumby trick on me, really. I hadn't a chance of passing through that rushing inferno outside. That left me one way out: through the front door. Hefting the wirecutter in my hand, and breathing a silent prayer, I moved back to that open doorway. Things, when I peeked out, seemed no more advanced. Man and sugarfoot were still clacking away at one another, neither side giving ground. However, the other men round about were showing signs of restlessness. "Whyn't ya just blast him, Jim, and forget it?" suggested an oldster just over to my left. Jim, the bartender, faced the other men with a black scowl, furious at the interruption. "You keep your mouth shut, Barry! You know these things can understand a little English!" The older man, Barry, subsided with a sullen look at Jim, and I turned my gaze there to see what would happen next. I'd quite overlooked the fact that Jim's looking toward Barry had sent his eyes in the general direction of the corridor, and that I was leaning my fool head around the doorway. Jim was looking right at me, his mouth wide open. "Hey!" he cried, leaping to his feet and pointing with such violence that his chair crashed to the floor. "He's loose!"