Leah is set up in a ground-floor room, with a wooden desk, a chair, a number of empty shelves, and a pile of random metal bars: copper, bronze, tin, zinc, iron, brass, steel. Most are too big for her plans, but a junior smith has volunteered to help her out, as has John.

Through John’s translation, the smith – Kesti – explains that he’s from right next to Devad, and that he knows the power held by members of the chemical experimentation committee. To be himself a part of that sort of working is a great honour, however his skills may be of assistance.

Though it’s already early afternoon, they fire up a forge to shape the ingots into a series of looped nails, like a capital letter ‘P.’ Taking notes on a scrap of parchment, Leah tests every pair of diodes, trying her best to remember how lemon batteries work. She starts with basic vinegar, from the kitchen, and she clearly remembers copper pennies being one of the components, but the rest is a vague blur.

Aluminum batteries? No, what’s the name? The rechargeable ones? Nah, I doubt they’d have discovered lithium yet. I’m pretty sure it’s in the name, I just can’t remember the name. We’ll just try one at a time. God, this would be so much easier with a voltmeter.

She uses a tightly wrapped coil of copper wire, about an inch long and just a bit wider than the quill she used to shape it, for all the tests. There is a significant quantity of iron filings in storage – apparently they are useful for certain spells, among other powdered metals and gems. She scatters them over the coil for every test, leaving a thin layer over a sheet of paper, and uses the clearness of the patterns drawn in them to determine the strength of the current.

Iron-copper: undetectable. Bronze-copper: nothing. Tin-copper: unnoticeable. Zinc-copper: bingo.

The other two had started to get a little disappointed when, at every test that evening, the results were negative. However, at the fourth try, as Leah drops the latest pinch of filings over the coil, they shift as they fall. They settle into very clear lines on the paper below, running along the length of the coil and dissolving into random distribution outside it.

“Which one is tha?” John asks, examining the pattern.

“Zinc,” Leah says, putting it aside to remember it and making a quick note. “What do you guys even use zinc for?”

Kesti, through John’s translation, explains that it is a garbage metal from Nent. “Mainly we use e teu make brass and other alloys; e has no use on es own, but you said you wanted teu try everytheng.”

“Well I’m glad you thought of it, because I wouldn’t have.” She tests the others just to be sure there’s nothing stronger, then goes back to zinc. It feels right, though; zinc batteries. I feel like I’ve heard that term before.

She explains, in a sort of distracted ramble, that the voltage is very weak, but you can string multiple “lemons” together and build up a stronger charge. John and Kesti nod along uncomprehending, and as night approaches they watch her pour vinegar into a series of ten glass jars, each jar holding one of each nail; she strings them together with copper wire, with the loop being closed at the small coil. They run the iron filings test again, and this time the pattern is very clear; straight lines below the coil’s core, with slight flaring at each end. As soon as they break the circuit the coil loses its ability to direct the filings.

It being fully night at this point, Leah notes down her findings and dismisses her two assistants. “Do we try more tomorrow?” John asks.

Leah nods, rubbing at her heavy eyelids. “We should. I want to build up a stronger charge before reporting any success; I don’t know what sort of effect I can hope for, or how long it will take to get there, but I want to be able to accurately estimate how useful this is actually going to be.”

She disassembles all the pieces, and heads up to her rooms well into the night. She finds it hard to fall asleep in her bed, her mind distracted trying to dredge up details from high school science classes, or curiosity videos online. Sleep arrives only much later, and even then is full of dreams of whiteboards and tests and textbooks.

At breakfast, she meets up with Kesti and John, who say they are eager to continue. They return to the lab, and Leah asks her assistants to find more copper wire and bottles. It’s a better demonstration with a light bulb, but I doubt they understand the concept of a ‘noble gas,’ much less have any in stock.

John returns from the kitchens with empty pickling jars, and Kesti with a spool of wire. She increases their battery from ten to twenty jars; the magnetism effect is strong, but only truly impressive to someone who already understands electricity, she fears. Certainly the wonder has worn off for her two assistants. Kesti, having made an abundance of the necessary electrodes, she has dismissed with her thanks, to let him go back to the work of preparing the Hold for a possible assault. John’s translation services no longer being needed, she dismisses him too, despite his apparent desire to remain and help.

I hope this is right. I don’t want to be wasting people’s time with a wild goose chase. Things are getting too dire to waste time with science projects.

Seffon arrives shortly after she finishes the twenty-jar test. Leah is already preparing an apology, that she doesn’t remember enough or have the tools to make something truly useful.

“Well, whatever you’re doing, it’s working.”

Leah stops with her mouth open, apologies dying on her lips.

Seffon grins. “The student next door was doing an exam, and you fouled his transmutation spell mid-process.”

“Oh. Damn. Sorry. But hey! It works!”

“Yes it does. What is it?”

Leah demonstrates the process of giving the coil a magnetic field. Seffon’s brief flinch when the circuit is connected shows her that he notices something the moment the current starts running, and she feels vindicated. When she demonstrates the magnetic field itself, he is intrigued, though obviously doubtful.

“How could this be a weapon?”

“Many ways. You can use it for electromagnetic guns, which use magnetic force to launch a projectile at high speeds – like a sling, but twenty times deadlier. The projectile can pierce clean through the target. Then there are tasers, which are like a portable source of very mild lightning strikes.” The second one intrigues Seffon more, she notices, and she hurries to qualify her statement. “Unfortunately this is all outside of my expertise; I lack the necessary understanding and materials, and it would be impossible for me to make any of those items.”

“We don’t need them, anyway,” Seffon says. “The tests of the iron bands have confirmed your theory; the static charge they build up by rubbing against the wool effectively blocks most simple magic directed at the wearer, though a close-range or very powerful attack completely overlooks it.” Seffon picks up one of the glass jars, looking at it curiously; he holds it gingerly, even though the circuit is currently broken. “Something like this system is much more powerful – the spell Lem was being tested on was simple, but required a lot of focus and control. He was halfway through force-growing a tree, and the whole process stopped dead in its tracks when you connected this thing.”

“So then,” Leah muses, “If we could make this set-up wearable, would it halt most attempts at harming or divining the wearer? And if so, at what distance?”

Seffon’s eyes light up. Leah grins, matching his curiosity, and starts directing him around the room. “I’ll stand here, and you…yeah, there’s good.” They position themselves on opposite sides of the battery, a few feet apart. Seffon begins a scry spell, holding a small glass bead in his hand.

“I’ve got you,” he says; Leah steps to the battery and turns it on. “Oh wow. And suddenly, you’re gone.” Leah steps back a few feet from the battery, slowly, until the bead in Seffon’s hand shows a faint image again. “And you’re back.”

“Five metres,” Leah says, estimating the distance to the battery. “Now like this.” She sets the battery on the ground and steps into the loop of wires.

Seffon frowns at the bead, pacing the room, advancing and retreating, as though looking for signal on a cell phone. Leah beams, watching the frustration mount in his face, his heavy eyebrows knit close together in focus.

“I have to be within three paces of you before I get anything,” he says finally, sounding a little insulted. He approaches to be standing right outside the ring of wire. “And I have to be here before the image is respectably clear.”

“How does that compare to the iron rings?”

“Pfft, ridiculous,” Seffon says, pocketing the bead, then kneeling down to undo the battery. “If you don’t mind…”

“No of course,” Leah says, stepping out and transferring the broken circuit back to the table. “But why ridiculous?”

“Compared to my past experience with the amber-iron rings, and my recent tests, they make a scry ineffectual only at a distance of greater than about, oh, seven hundred metres? And they only block things targeted directly at the wearer, but as we’ve seen with the tree, this stops all nearby casting.”

Leah looks down at the flimsy battery set-up. “I guess I’ve found my job,” she says, bemused.

“You can pass through someone’s territory unseen, wearing the rings; with this, you could walk right up to them and they’d never know.” Seffon’s hands flit over the battery, examining the components, curious and acquisitive. “Well, you’d be visible, but you’d be hidden from magical detection, and that’s useful in its own way.”

Leah remembers Solace’s comment during the escape. “I was given the impression that true invisibility is not possible with magic; is that really the case?”

Seffon hums and makes a face. “Only in practical terms. It’s possible to cast an illusion to change everything about yourself, because that’s just a second layer you apply over your body, but the illusion must be larger than you, so you can’t just illusion yourself into a flea and be nearly invisible like that. If instead you tried to create an illusion of emptiness to hide behind, you would have to know what’s behind you at all times, and measure the visual angle of the person looking towards you relative to your background, and relative to the surface of the illusion you create. Even if you could do that, it would only work if only one person was looking at you, and both they and you were absolutely stationary.”

Leah nods, impressed, then accepts this as reasonable.

“I’ll get to work making this set-up portable,” she says, looking back to the table. “I’m glad it’ll have a defensive use. Not that an offensive use would be bad, but…I understand that the idea that something could attack a person’s ability to cast is pretty existentially horrifying. Even using it defensively is…walking a pretty thin line between protection and aggression.”

Seffon is solemn, then shrugs it off. “Magic users are often viewed as more powerful than they really are; people imagine us to have godlike abilities, and that leads them to fear. If they thought they could get rid of us…”

Leah remembers his mention of genocide and simply nods with understanding. “Teo said something like that.”

Seffon nods, then looks confused a moment. “When did you meet Teo?”

“She gave me chocolate, yesterday. Apparently she won a bet, that I was trustworthy. All the other students bet that I was either an assassin or a spy.”

He accepts this with an impressed look. “Hmm. Good for her. How did you bet, Lem?”

Leah notices for the first time that the student from the test has been eavesdropping behind the doorframe. He leans his head in once his name is said, long black hair tied loosely back from his face.

Seffon frowns at him critically. “Yu cannau yven spy Volsty; ua de yu expe teu learn?”

Lem steps around the corner sheepishly. “I fel th…theng…go auff again, an I wan’ teu sy ʁau e wõ’.”

“De yu know abou th be?”

Lem looks uncomfortable. “I dednau tae pã.”

Seffon hums unbelievingly. “Uy’ll fenes yõ tes en a men. Uai en th reum.”

Lem spares another glance at Leah and the contraption, then gives a tiny nod and leaves.

Seffon turns back to Leah. “You don’t take it personally, I hope? The bet?”

“It’s hard not to. However, I understand where they were coming from. I hope I’ve proven myself enough to them.”

“You don’t need to prove yourself to them. You’ve proven yourself to me.” Leah smothers a grin at this, unexpectedly touched. Seffon turns to go, then stops. “Oh! Head up to the tower, after lunch; I’ve got an idea for another spell attempt. Just so you don’t think I’ve given up on finding out how you got here, and how to get you home.”

Leah nods. “I’ll try to finish this before it’s time to send me back,” she jokes, gesturing to the battery, and Seffon leaves with a grin.