Astounding Stories of Super-Science, August 1930

"People of America!" it said. "We of the planet Vada have come to conquer your country. You will be given forty-eight hours to lay down your arms. If complete surrender has not been made by high noon, two days from now, New York will be destroyed." The voice ceased. The humming recommenced--waned in volume till it died away. Twilight turned once more to midday. Peering fixedly through the west windows of the laboratory, the little assemblage saw the disc swallowed up in the clear blue sky. Then they turned, faced one another gravely. Outside, on the streets, confusion reigned. In newspaper plants, presses were whirling. In telegraph and cable offices, keys were ticking. From radio towers, waves were speeding. Within an hour, the nation and the world knew of this planetary invader and its staggering ultimatum. Naturally, the government at Washington refused to meet these shameful terms. Military and naval forces were rushed to the threatened metropolis. The Atlantic Fleet steamed up from Hampton Roads under forced draught and assembled in the outer harbor. Thousands of planes gathered at Mitchell Field and other nearby aerodromes. But where was the enemy? He must be miles up in space, Kendrick knew, as he toiled feverishly in the laboratory over his experiment after a sleepless night. For had that flying city been nearer earth, it could not have maintained invisibility without that peculiar humming vibration. Scout planes urged on by impatient squadron commanders, climbed till they reached their ceilings, searching in vain. They could encounter nothing, see nothing of the invader.