Bill frowned. "Dampier, give me those equations. I've got to puzzle this thing out for myself, follow your argument through on paper. Is there any place where I can be quiet?" "But of course, Monsieur. There, in the room for thermal work, everything will be perfectly quiet. Here are the papers, and while you read, I shall show Monsieur Crandall the working of the works." But Bill didn't hear that last. The heavy door of the constant temperature room had closed behind him and insulated him from the world. I couldn't do much but stand and watch Dampier as he bustled about, tuning up his crazy-looking machine. He talked a blue streak as he worked, but most of it went right over my head. I'm no Bill Porter. I did begin to see why Nebel, if he was behind the world's armaments racket as Dampier claimed, might be pretty anxious to get hold of such a thing before the little Frenchman began peddling it to his best customers. In the right hands it might make war very unfashionable. Imagine an invaded nation squatting down behind a perfectly reflecting wall. They can't see out, but nothing can get in. Enemy shells bounce off into the enemy lines. Death rays flash back into the faces of those who sent them. Radio is garbled by all kinds of curious echoes and reflections, making communication impossible. Electrical and magnetic apparatus would be subject to strange disturbances. And gravitation--how would it affect that? Would every outside object be attracted to the mirror, or would it be repelled by a kind of negative gravity, lifting it into space, to the moon, the planets, to the very stars? I wish now that I'd known at least a fraction of what Bill did, and had been able to read what he read in these few sheets of neatly written paper. I can only guess, from what Dampier said and from what I saw. What his zone really was--what it could do--I do not know. I tried to pay attention to what he was doing. The real vitals of his apparatus were in the big insulated block. The thousands of amperes he was drawing from the high-tension lines were merely the kicker that kept the real engine turning. Atomic energy, Bill had guessed. Probably he was right. The loops and coils above the platform determined the shape that the zone would take. According to how they were set, Dampier explained, he could get any geometrically continuous form--a disc, a paraboloid, anything that geometry can describe. What he was going to make was a sphere.