Ships went out, their purpose to shell the Northern ice-cap where the machine held forth. Aircraft could not be trusted but ships--turned in the ocean and returned, their electrical wiring paralyzed as much as the control equipment had been on the two grand fleets of aircraft. Men set off on foot to attack the machine-- A half a million men started to march to the North. Days went by, days in which they were gone from sight from the Northernmost end of the steam railway lines. Days later they were stopped. Far in the distance they could see the Building of the Machine, but between them and it was a patch of open water. Ships plied this passageway, ships that broke up the ice and kept it a churning, grinding place for death to any man so foolish to try a crossing. The machine was as isolated as any medieval castle surrounded by its moat. In futility, they turned and began the long, cold march home. How--bare-handed--could they hope to fight a machine equipped with better than the best of mechanistic devices ever invented by mankind? They could not. 8 Vinson threw down his pencil. "Theory holds," he said ruefully. "But unless we can prove it we are beaten. And how can we prove it when nothing but pencil-and-paper proof is available?" "You are still postulating a new means of communication?" asked Narina. Vinson waved one of the metal cubes taken from some machine--somewhere. "This is it," he said. Narina shrugged and looked at the big calculator in the laboratory. "That has none," she said. "True," he agreed. "But remember that the machine may have required some artificial means before it was joined into the master thinking machine." Narina nodded glumly. "Cube of metal or none," she said, "it gives the wrong answers. Now--" Narina's next observation was never made. A roar came from outside--far in the distance but none the less a roar of voices in fear, in determination, in wonder. Then the roar of voices was mingled with the whistling roar of jet-propelled aircraft that screamed over the top of the laboratory building and circled. Ignoring the bare-handed men on guard, these aircraft landed and disgorged a myriad of small machines. And from the water of the bay there appeared a similar horde, but these were huge and lumbered forward on tractor treads, shedding water as they came. Dynamite roared and a gap was blown in the advancing line of machines. The rest came on while a corps of small machines collected bent and twisted bits of destroyed metal. Ignoring the attempts of men to stop them, several of the larger machines encamped and dug into the earth-- Setting up a repair-production line! Broken and damaged machines were run down a conveyor belt. Darting girders carrying tools flashed in and out and damaged members were removed, repaired, and replaced. More planted dynamite roared skyward with its toll of machines and there was more work for the repair-- _The hospital corps!_