steadying as one's own image. Actually, your body is taking the mental shock very well." He stared at his image. There was a paleness in the lean face that stared back at him. But his body was not actually shaking as the whirling in his mind had suggested. He grew aware again of the girl. She was standing with a finger on one of a series of wall switches. Abruptly, he felt better. "Thank you," he said quietly. "I certainly needed that." She smiled encouragingly; and he was able now to be amazed at her conflicting personality. There had been on the one hand her inability a few minutes earlier to get to the point of the danger, an incapacity for explaining things with words. Yet obviously her action with the mirror showed a keen understanding of human psychology. He said: "The problem now is, from your point of view, to circumvent this Isher woman and get me back to 1951 before I blow up the Earth of ... of whatever year this is." The girl nodded. "Father says that you can be sent back, but as for the rest, watch!" He had no time for relief at the knowledge that he could be returned to his own time. She pressed another button. Instantly, the mirror was gone into metallic wall. Another button clicked. The wall vanished. Before him stretched a park similar to the one he had already seen through the front door, obviously an extension of the same gardenlike vista. Trees were there, and flowers, and green, green grass in the sun. One vast building, as high as it was long, towered massively dark against the sky and dominated the entire horizon. It was a good quarter mile away; and incredibly, it was at least that long and that high. Neither near that monstrous building, nor in the park, was a living person visible. Everywhere was evidence of man's dynamic labor, but no men, no movement. Even the trees stood motionless in that breathless sunlit day. "Watch!" said the girl again, more softly. There was no click this time. She made an adjustment on one of the buttons, and the view was no longer so clear. It wasn't that the sun had dimmed its bright intensity. It wasn't even that glass was visible where a moment before there had been nothing. There was still no apparent substance between them and that gemlike park. But the park was no longer deserted. Scores of men and machines swarmed out there. McAllister stared in amazement; and then as the sense of illusion faded, and the dark menace of those men penetrated, his emotion changed to dismay. "Why," he said at last, "those men are soldiers, and the machines are-" "Energy guns!" she said. "That's always been their problem. How to get their weapons close enough to our shops to destroy us. It isn't that the guns are not powerful over a very great distance. Even the rifles we sell can kill unprotected life over a distance of miles, but our gun-shops are so heavily fortified that, to destroy us, they must use their biggest cannon at point-blank range. In the past, they could never do that because we own the surrounding park, and our alarm system was perfect-until now. The new energy they're using affects none of our protective instruments: and, what is infinitely worse, affords them a perfect shield against our own guns. Invisibility, of course, has long been known, but if you hadn't come, we would have been destroyed without ever knowing what happened." "But," McAllister exclaimed sharplv, "what are you going to do? They're still out there, working-" Her brown eyes burned with a fierce, yellow flame. "My father has warned the guild. And individual members have now discovered that similar invisible guns are being set up by invisible men outside their shops. The council will meet shortly to discuss defenses." Silently, McAllister watched the soldiers connecting what must have been invisible cables that led to the vast buildings in the background; foot thick cables that told of the titanic power that was to be unleashed on the tiny weapon shop. There was nothing to be said. The reality out there overshadowed sentences and phrases. Of all the people here, he was the most useless, his