Stranger by Sherwood Smith

blinked. “You’re right. I hadn’t thought of it that way before.”
    Ross’s expression eased into genuine interest. Encouraged, Jennie went on. “Mia designs and builds things, and prospectors . . . what do you do? How do you get into those ruins? How do you even find them?”
    â€œMaps. Old stories.” He spoke slowly, but with a tentative confidence. “If you get up high, you can see ruins, sometimes.”
    â€œGo on,” Jennie said, smiling.
    Ross flicked a glance at Mia, who nodded encouragingly. “But even if they’re buried, the way the plants are growing can show you there’s something underneath. As for getting in, you can dig if they’re not too deep. If it’s a collapsed structure, you have to shore it up so it won’t fall on you. Sometimes you have to blast your way in.”
    â€œHow do you do that without blowing up the whole thing, or making the collapse even worse?” she asked.
    Behind Ross, Mia automatically raised her hand, then quickly lowered it, embarrassed.
    â€œSee what the structure is made of,” said Ross. “Look for a wall that isn’t the sole support of anything. To figure out how much explosive you’ll need, you have to calculate the overpressure.”
    As Jennie had suspected, however spotty the guy’s overall knowledge was, he knew a lot about his own field. “How do you do that?”
    Mia caught her hand halfway up, then sat down abruptly on the little kids’ bench, trapping both hands under her thighs.
    â€œWith a slide rule,” he replied.
    â€œI see,” said Jennie. “Ross, there’re only three or four people in town who know how to do that, and two of them are here in the room with you.”
    Mia extracted her hand to tap the slide rule dangling from her waist.
    â€œHow much can you read?” Jennie asked.
    Ross ducked his head. “Only numbers. Well, a couple letters you use in math.”
    â€œWhat about history?”
    â€œI don’t know anything. I just wonder. How the things I find got there. What people used them for. Why all the cities were destroyed.”
    â€œI know that one!” exclaimed Mia before Jennie could answer. “According to the accounts we’ve found, it was a natural disaster. There was a storm on the sun, and it released radiation. Do you know what that is?”
    â€œNo,” Ross muttered, embarrassed.
    Jennie wished she could tell him that she’d never heard Mia this eager to talk to anyone but her father, her old master, Mr. Rodriguez, and Jennie herself. However had Ross gotten Mia to trust him so quickly?
    â€œIt’s a sort of energy,” Mia went on. “Like light. It changes living things. Some animals and plants died, and some mutated. Some people died, and others got the Change. Also, the solar storm caused a geomagnetic storm on the Earth. Not a storm with rain. It was a change in the Earth’s magnetic field.”
    Ross glanced up. “That’s what makes a compass work, right?”
    Mia’s head bobbed enthusiastically. “Yes! Exactly. And back then, nearly everything was mechanical. When the magnetic field changed, most machines stopped working. People had to leave the cities and start farming, and eventually the cities got overgrown and knocked down in earthquakes and storms. And then singing trees started growing around them, so no one could get back in.”
    Ross pulled his left arm in across his chest, rubbing it as if it hurt. “The books. Tell me what happened to the books.”
    Under his direct gaze, she fiddled nervously with her glasses. “Maybe Jennie could explain it better.”
    â€œYou go on. You’re doing great.” Jennie winced inwardly once the words were out. She sounded like she was talking to a little kid.
    But Mia didn’t look insulted. “Back then, most books were machines. I don’t understand how that worked.