_The two globes went spinning toward the Enemy. Linked together, they spun round and round and no conceivable computer could calculate the path of either one so a projectile could hit. They did not travel in a straight line, as a trajectory in space should be. Whirling as they did around a common center of gravity, with the plane of their circling at a sharp angle to their line of flight, it was not possible to range them for gunfire. Their progress was in a series of curves, each at a different distance, which no mere calculator could solve without direction. A radar could not pick up the data a computer would need. One or the other globe might be hit, but it was far from likely._ _The pilot of the one-man ship saw the blue-white flame of a hit. He flung his ship about and sped back toward the fortress. The Enemy would beat this trick, in time. Four thousand years before they'd almost won, when they invaded the Old Nation. They were getting bolder now. There was a time when a sound beating sent them back beyond the Coal-sack to lick their wounds for two thousand years or better. Lately they came more often. There'd been a raid in force only five hundred years back, and only fifteen before that ..._ * * * * * Holmes, obviously, had the odd dream Burke had prophesied. But Burke was up in the instrument-room by then. Keller gazed absorbedly at a vision-plate. It showed a section of the exterior surface of the asteroid--harsh, naked rock, with pitiless sunlight showing the grain and structure of the rock-crystals. Where there was shadow, the blackness was absolute. As Burke entered, Keller turned a knob. The image changed to a picture of a compartment inside the fortress. It was a part of the maze of rooms and galleries that none of the newcomers had visited. Panels and bus-bars and things which were plainly switches covered its walls. It was a power-distribution center. Keller turned the knob back, and the view of the outside of the asteroid returned. Keller turned and blinked at Burke, and then said happily, "Look!" He went to another vision-screen with an image of another part of the outer surface. He turned that knob, and the image dissolved into another. This was a gigantic room, lighted like more familiar places. In its center there was an enormous, gigantic machine. There were domes of metal, with great rods of silvery stuff reaching across emptiness between them. There were stairs by which one could climb to this part and that. Judging by the steps and the size of the light-tubes, the machine was the size of a four-storey house. And on the floor there were smaller machines, all motionless and all cryptic. Keller said with conviction, "Power!"