***** Trapped in the great dome, Darl valiantly defends Earth's outpost against the bird-man of Mars and his horde of pigmy henchmen. Darl Thomas mopped the streams of perspiration from his bronzed face and lean-flanked, wiry body, nude save for clinging shorts and fiber sandals. "By the whirling rings of Saturn," he growled as he gazed disconsolately at his paper-strewn desk. "I'd like to have those directors of ITA here on Mercury for just one Earth-month. I'll bet they wouldn't be so particular about their quarterly reports after they'd sweated a half-ton or so of fat off their greasy bellies. 'Fuel consumption per man-hour.': Now what in blazes does that mean? Hey, Jim!" He swiveled his chair around to the serried bank of gauge-dials that was Jim Holcomb's especial charge, then sprang