"I wasn't thinking so much of bombs."
"What, then?"
"Isotopes. A good, thick blanket of dust. Slow-speed, fine stuff that neither our ships nor the Hill's screens could handle. We've got to decide, first, whether Virgil will be safer there in the Hill or out in space in the Chicago; and second, for how long."
"I see ... I'd say here, under the Hill. Months, perhaps years, before anything could work down this far. And we can always get out. No matter how hot the surface gets, we've got enough screen, heavy water, cadmium, lead, mercury, and everything else necessary to get him out through the locks."
"That's what I was hoping you'd say. And now, about the defense ... I wonder ... I don't want everybody to think I've gone completely hysterical, but I'll be damned if I want to get caught
