Sol stopped, discommoded by the markers."If it is safe, why are they still here?" he demanded. Sola noddedheartily, unashamed of her fear,

      "Because the crazies haven't updatedtheir maps in fifty years," Sos replied. "This area is overdue forresurvey, and one of these months they'll get around to it and set the markersback ten or fifteen miles. I told you radiation isn't a permanent thing; itfades away slowly."

      Sol was not convinced, now that commitmentwas imminent. "You say this 'radiation' is something you can't see or hearor smell or feel, but it kills you just the same? I know you studied the books,but that just doesn't make sense to me."

      "Maybe the books are lying,"Sola put in, sitting down. The days of forced marching had tightened themuscles of her legs but diminished none of her femaleness. She was agood-looking woman and knew it.

      "I've had doubts myself," Sosadmitted. "There are many things I don't understand, and many books I'venever had the chance to read. One text says that half the men will die whenexposed to 450 Roentgen, while mosquitoes can survive over a hundredthousand-but I don't know how much radiation one Roentgen is, or how to spotit. The crazies have boxes that click when they get near radiation; that's howthey know."

      "One click to a Roent, maybe,"she said, simplifying it. "If the books are honest."

      "I think they are. A lot of it makesno sense at all, at first, but I've never caught them in an error. Thisradiation-as nearly as I can make it, it was put here by the Blast, and it'slike fungus-light. You can't see the fungus glow in the daytime, but you knowthat light is still there. You can box it with your hands to shut out the sun,and the green-"