"With electrical scanning, you'll have curvature of field with this gadget. That isn't too bad, I suppose, because the restorer will have the same curvature. But you're going to scan three ways, which means correction for the linear distance from the tube as well as the other side deflections and their aberrations. Now if we could scan the gadget mechanically, we'd have absolute flatness of field, perfect focus, and so forth." Walt grinned. "Thinking of television again? Look, bright fellows, how do you move an assembly of mechanical parts in quanta of one atomic diameter? They've been looking for that kind of gadget for centuries. Dr. Rowland and his gratings would turn over in their graves with a contrivance that could rule lines one atom apart." "On what?" asked Don. "If it would rule one atom lines, brother, you could put a million lines per inch on anything rulable with perfection, ease, eclat, and savoir faire. You follow my argument? Or would you rather take up this slip of my tongue and make something out of it?" "O.K., fella. I see your point. How about that one, Wes?" Wes Farrell grinned. "Looks like I'll be getting perfect focus with the electrical system here. I hadn't considered the other angle at all, but it looks a lot tougher than I thought." He squinted through a wall-mounted telescope at the set-up on the inside of the blister. "She's hot," he remarked quietly, and then set to checking the experiment. Fifteen minutes of checking, and making notes, and he turned to the others with a smile. "Not too bad that way," he said. "What are you doing?" "I've established a rather complex field. In order to correct the aberrations, I've got nonlinear focusing fields in the places where they tend to correct for the off-axis aberration. To correct for the height-effect, I'm putting a variable corrector to control the whole cone of energy, stretching it or shortening it according to the needs. I think if I use a longer focal length I'll be able to get the thing running right. "That'll lessen the need for correction, too," he added, cracking the blister-intake valve and letting the air hiss into the blister. He opened the door and went inside, and began to adjust the electrodes. "You know," he added over his shoulder, "we've got something here that might bring in a few dollars on the side. This matter-bank affair produces clean, clear, and practically pure metal. You might be able to sell some metal that was rated 'pure' and mean it." "You mean absolutely, positively, guaranteed, uncontaminated, unadulterated, perfectly chemically pure?" grinned Don. "Compared to what 'Chemically Pure' really means, your selection of adjectives is a masterpiece of understatement," laughed Walt. "I'm about to make one more try," announced Wes. "Then I'm going to drop this for the time being. I've got to get up to the machine shop and see what they're doing with the rest of the thing." "We'll take over that if you wish," said Don.