Swiftly they were looming before us as we rushed on toward them, giant domed cubes of dull metal, each five hundred feet in width, that hung in a great, curving line in mid-air before us, five miles above the green land. At intervals of five miles they hung, floating motionless there in a great grim chain or ring, the metal sides and dome of each bristling with great heat-guns like those of our own cruisers, and with narrow openings from which the occupants could gaze forth. Each of these great air-forts, we knew, was suspended thus high above the ground by the gravity-repelling effect of the cosmic rays. It had been but fifty years since the machinery had been discovered which directed the great power of the cosmic rays to overcome the force of gravity. It had been found that the rays could be collected and their power concentrated in the structures that they were to support. Dynamic towers were used for the collection of this great limitless energy. In a great ring they hung before us, the line of them curving away vastly to right and left, a great ring that encircled and defended New York, as air-forts hang in rings about all air-cities for defence. Then as we drove toward the nearest of these great fortresses of the air, there came from the distance-phone before me its sharp challenge. Swiftly I replied to that challenge and then we were driving past the air-fort, past the openings in its walls through which we could see those inside standing ready at the great heat-guns. We heard faintly their cheers as we flashed past them toward the east; we cheered ourselves somewhat by the sight of the air-forts. They could maneuver in space in any direction, though at only a fraction of the speed of the air-cruisers. They would form a stubborn defence for New York, we knew, though incapable of meeting alone a swift invading fleet. But now far ahead, as we rushed within the mighty ring of the air-forts, we glimpsed the gray gleam of the Atlantic's vast expanse, stretching away to the east, the green, irregular coastline, the narrow little island, between a larger island and that coast, that had been the site of the New York of fifty years before. Green and deserted as all the countryside behind us it lay now, but I glanced at it only, looking up as there came a low exclamation from Hilliard, beside me. "New York!" Full before us lay the mighty city, now, waxing with each moment greater as we raced on toward it. The air about and beneath us was filled with the great swarms of cruisers like our own and of merchant-traffic that was converging from north and west and south upon it. For the moment we three gazed toward it, forgetful of the peril that had brought us to it. We were caught and entranced as always by the splendid and superb beauty of this New York. For it was a New York immeasurably different from that city upon the earth, that decades ago had born its name. It was a city, not of the earth, but of the air.