"Orthos? That could be short for any number of scientific terms, Phil, but I bet you mean the ones that shoot. Those are ortho-fissionables. Trouble with ordinary fissionables--or fissionables under ordinary circumstances--is that the fragments and neutrons shoot off in all directions and the critical mass is large. But if you get the fissionable atoms all lined up with their axis of spin pointing in the same direction, then they all split in the same place and every neutron hits the nucleus of the atom next to it. Because of that last fact, the neutrons are all used up and the critical mass becomes minute. Half the fragments fly in one direction, half in the other, making it a very nasty and convenient weapon, except it has to backfire." "How do you get the atoms lined up?" Phil asked eagerly. "Temperature near absolute zero and an electric field," Opperly said, touching a button beside the doorway. "Simplest thing in the world. The new insulators can hold a gun magazine at one degree Kelvin for weeks, and carry enough fissionable pellets to give rapid fire, with the effect of a steady beam, for more than a minute. Planning to make yourself an ortho in your home workshop, Phil? I'm afraid they don't sell that kit. Everything I've been telling you is top security, death penalty and all that. But I'm getting so senile I don't understand security regulations. I'm apt to babble anything. I keep telling Bobbie T. he'll have to have me orthocuted some day, but like everyone else he refuses to take me seriously. That's the trick they used on me in WW3 and they've never forgot it." "Bobbie T.?" Opperly made another of his apologetic grimaces. "Barnes. President Robert T. Barnes. We were charter members of the Midwest Starship Society. Of course he was just a shaver then and now he's a besotted, scripture quoting fox, but shared dreams have a way of linking people permanently. I drop in on him now and then and flash my Starship badge. He's one of my pipelines to what's happening in the world, though the security services don't tell him too much. That's how I learned about the green cat." Phil was nerving himself to ask Opperly just what he'd learned, when he heard footsteps behind him. The man who looked like a brother of the girl with hoofs was standing in the gateway. Just then the door of the mansion opened, revealing a scholarly appearing man whose face was twitching with excitement and nervousness. His coat had two bulging brief case pockets, while his vest was crammed with enough microbooks to make up a dozen encyclopedias, plus two micronotebooks with stylus, and a fountain pen besides. His hair was graying and thin, and he wore ancient pince-nez that twitched with his nose. "Dr. Opperly!" He greeted in a high-pitched voice that expressed both fluster and delight. "You come at a whirling moment!" "That's the way I like them, Hugo," Opperly told him. "Where's Garnett?"