Again he saluted and disappeared, leaving us staring blankly at each other. Then we were struggling into the tight black jackets of our uniforms, were striding out in a moment and down to the great air-city's "ground" level in one of the building's electrostatic-motored cage-lifts. Through the crowded streets we strode, seeing now that in all those streets other black-uniformed men of the squadrons named were pressing toward their cruisers in the central plaza. Then we three had reached that central plaza, from whose center rose the mighty electric power-tower, and around which the two hundred and fifty cruisers rested, all of our first four squadrons that had survived the battle. Already, I saw, the crews of those cruisers were taking their places within them, and as Macklin and Hilliard took up their positions in our own I strode on across the plaza toward the huge tower's base, in which were the headquarters of the First Air Chief. Passing challenging guards at its door, I passed through a few narrow white-lit ante-rooms, and then had stepped into the great circular room that was his innermost office. The curving walls of that room were covered with panel after panel of instruments and switches, which controlled the vast electrical currents that rushed down from the electric-tower's tip and transformers to those motors in the city's base. Near the room's center was the battery of six great switches which controlled the city's direction of motion, moving it in any direction at will at slow and ponderous speed, the speed-control's gleaming knob beside them. And beyond the controls of the great air-city, there stood a great table-map of the world, upon which a myriad of red circles automatically showed the position of the world's air-cities. Behind this table-map, as behind a desk, the First Air Chief was sitting as I entered, while around the panelled walls there moved a half-dozen black-jacketed attendants constantly watching and controlling the flow of current from the power-tower's tip to its motors. The First Air Chief, as I entered, motioned me silently to a metal seat before himself, at the great table-map's edge, and then for a moment contemplated me in silence, as though considering his words before speaking. Regarding me intently, he began. "For a second time, Captain Brant," he was saying, "I have summoned you here to me, but this time alone, and with the two hundred and fifty remaining cruisers of our first four squadrons summoned also outside. You are wondering, no doubt, why I have done so.