Follows A Little Spark 04

>You're fortunate the weather is good, because everypony involved insisted on conducting your experiment outdoors.
>Twilight had teleported it out of your workshop in pieces, but reconnecting everything wasn’t too difficult.
>A private garden for the princesses now hosts four individuals and one jury-rigged machine.
>Twilight stands at one end of the device, a metal shaft sticking out of it towards her.
>Celestia sits on a balcony on the other side of the machine from you, to intervene in case something goes catastrophically wrong.
>You stand near a hand-wheel that controls the transmission, in front of a big sliding bar that indicates the transmission’s current setting. A paddle with one red and one green side rests on top of a notepad on the control box.
>Behind you sits a guest you requested Twilight bring; a musician with absolute pitch.  The gray earth pony holds ready a cello, and a violin sits on a table beside her.
“Alright, first run is a dry run. We’re going to see how fast we can crank this thing, and establish some base values. We’ll put some weights on after to simulate loads.”
>You crank the hand-wheel until the sliding indicator is at one end of the bar, then give Twilight a thumbs up
>The shaft near her lights up with a magenta glow, and the machine starts turning
>A lone rubber flap at the far end of the machine starts slapping against a bar, once for every rotation. It picks up speed quickly as Twilight turns it faster, becoming a loud droning tone.
>You turn to look at the pony behind you.
“What are we hearing, Octavia?”
>She thinks for barely a moment. “E2”
>Now you just had to remember what frequency E2 was
“Uh, can you, uh… give me a G2 or something.”
>Octavia dutifully complies, bowing the cello’s second string with long, even strokes.
>You hold up your painted paddle with its green side facing Twilight
>She nods, then focuses on the shaft again. The drone starts slowly increasing in pitch.
>As the pitch gets closer to the note Octavia’s playing behind you, you turn the paddle to be more edge-on to Twilight. The drone’s increase in pitch slows down, and you can hear the moment they match.
>You turn the paddle edge-on. The drone’s increase slows to a crawl. You can hear a very slowly cycling pulse between the two, and start counting seconds in your head.
>When you count two pulses a second, you drop the paddle. Then you listen for a bit longer; this would be way easier if you could isolate yourself and listen to the two sounds alone, instead of dealing with echoes off the palace walls and the rattling of your thrown-together bearings.
>Satisfied, you draw your hand across your throat. Twilight stops the machine, and Octavia follows suit.
“Alright, that should have been about a hundred cycles a second. You were turning that bar far faster than that. Was the effort posing you any problems?”
>Twilight tilts her head in thought. “Not much, as long as I didn’t have to do it for a long time.”
>You make a few notes on your pad, then look back at her.
“Your speed control is remarkable. I didn’t think it’d work that well.”
>Twilight draws her head up and beams. Even Celestia’s smiling from her balcony perch.
“Alright, this time, just roll it as fast as possible. Go when you’re ready.”
>Twilight resumes right away, the drone quickly picking up speed. When it sounds like the pitch leveled out, you look back at Octavia.
>”D… Somewhere around D♯3”
>You do some quick math in your head. Then you flip  few pages back in your pad and look at some of your earlier calculations.
“Holy shit.”
>Twilight stands in a wide stance, staring at the spinning shaft like she wants to set fire to it with her mind, but she doesn’t look like she was about to fall over. There’s room to kick this up some more.
>You make another note on your pad, then grab the hand-wheel controlling your transmission. Slowly, you start cranking it.
>The drone starts increasing again, slowly at first, and then faster as you continue to crank.
>When you look up at Twilight, she’s staring back at you in alarm, chest heaving.
>You stop cranking the wheel and give her the stop signal. No use wearing her out so soon.
“How high’d we get, Octavia?”
>”Around D4, Anon.” She shifts her cello in her grip, then looks to her violin. “Will you want me to play over it?”
“Uh, yeah, why don’t you get ready for that.”
>While Octavia switches instruments, you make a quick note on your pad, then jog over to where Twilight’s catching her breath. Squatting down next to her, you look her over real quick.
>What are you even looking for? Damnit, you’re an engineer, not a veterinarian.
“Hey, sorry about that. Still don’t really know how the whole magic thing works.”
>”I’m… I’m fine. Did I ruin… your data?” She already looks a lot better, but is still panting.
“Only if you slowed down before I told you to stop.”
>She shakes her head no.
“Then we’re all good.”
>You look up to Celestia’s balcony. She's standing at its edge now, eyeing the two of you with an unreadable expression.
“Is she going to kill me if you collapse down here? Because we only found one end of your upper bound, we still have a whole curve to define.”
>”She’s just concerned, Anon. But next time… Warn me before you push me that hard.”
“Yeah, sure. Well I mean, this is your warning then. I want to see if magic is biased how it can be used to deliver power most efficiently. I had you spinning this thing as fast as possible, then started changing our gear ratio. Next step is working at the opposite extreme. Don’t worry, I wont be able to make it more difficult this time.”
>”You know, Anon," Twilight gives you a weary smile. "Usually I’m the one taking notes.”
“I promise I’ll share.”
>You reach out and tousle her mane just behind her horn as you stand and turn back to your post. You don’t even realize it until you stop; these pint-sized ponies are too precious for you sometimes. They’re like giant puppies, who’d be able to resist?
>Octavia’s giving you a weird look. She apparently doesn’t feel it important enough to actually tell you why, when you’re back at the control wheel.
>You look to your purple assistant again as you start cranking the wheel as far as you can.
>Twilight and Celestia are sharing some wordless communique by eye contact.
>You guess the Princess was just concerned for her after all.
“Whenever you’re ready, Twilight. As fast as you can.”
>Now the sliding indicator bar is pegged on the opposite side it started at.
>After taking about a minute to compose herself, Twilight faces the shaft again. Her eyes bulge in shock when she first tries to move it, but she leans into it, and gets it spinning again in short order.
>The droning sound of the smacking rubber flap very quickly escalates.
>Once it evens out, you back at Octavia.
“What are we at now?”
>You wonder if she can hear the pitch over the awful rattling of your crappy bearings. You’ll have to think of another solution.
>”Almost A4.”
>After making a few more notes, you grab your colored paddle, and show Twilight the green side.
>Then you start cranking back on the hand-wheel.
>The drone drops in pitch, at first, but quickly recovers. You stop your turning every once in awhile to pencil a line on the sliding bar and take notes, asking Octavia for the different pitches she hears.
>Eventually you’re back near the range you snuck up on Twilight the first time. You give her the stop signal.
“Alright, that was good. Lots of good data. Now lets put some weight on this and see what changes. If you could-”
>Disk-shaped weights – pilfered from a gym somewhere in the guards’ barracks – on the opposite end of the machine from Twilight start levitating, but are illuminated by a golden rather than magenta glow. They deftly slot themselves onto the shaft at that end.
>You look up at the balcony and give Celestia a thumbs up.
“Thanks. Uh, keep an eye on them, please, Princess. We don’t exactly have them secured in-place. If they start coming off, just sorta nudge them back again.”
>Celestia dips her head, in a gesture you’re not sure is a deep nod or a shallow bow.
“Alright Twilight, I’ll be going back up again. Try to keep it spinning as fast as you can; when it gets too heavy, just back off until it’s manageable.”
>Twilight nods and resumes her work immediately.
>You work your way back across the range again, taking more notes as you continue changing the ratios. Every so often you have Octavia play a note, and try to get Twilight to match it.
>Near the top of the range, you notice a larger dropoff than you’d expect.
>Twilight’s squeezing her eyes shut, standing in the same splayed stance from earlier. Her horn’s almost touching the rapidly-spinning shaft. Celestia’s looking back and forth between her and the weights, but you doubt Celestia’s seen what happens when bodies touch hardware spinning at those speeds. You have. Safety videos aren’t supposed to give you nightmares, but someone, somewhere, didn’t get that memo.
>This damn thing doesn’t have an emergency stop.
>You drop your notepad and hit a dead sprint in three strides.
>The palace tailor’s going to have to make something more mobile for you than this damn suit they insisted on copying from what you wore when you arrived.
>When you reach her side, you brace one hand against the machine’s frame, and place your other hand square on her chest, shoving her away as hard as you could. She stumbles and falls, and the shaft stops glowing.
>Celestia’s already over the balcony railing, gliding down to where you kneel, a look of great concern on her face.
“Before you ask, yes, I had to.”
>You tap the end of the now almost stopped shaft.
“She got too close. You don’t want to touch these things when they’re spinning that fast. This is just a pretty smooth bar, there’s not a lot to get snagged on, but I’m not going to trust that. If that weird magic aura’s able to interact with objects, I didn’t want to take the chance her horn would latch on and snap her neck before you even had the time to realize what was happening, let alone do something about it.”
>Celestia looms over your still-kneeling form. “It sounds like your technology carries some great risks.” Despite her intimidating presence, she speaks in a worried tone.
“There’s a reason I wanted to keep everything in the workshop. Once I have constant power, I don’t want some pony frying themselves or something. When the final generator’s built we can include all the safety features. I just… wasn’t thinking about that for this one-off design, especially when the final product will be much smaller.”
>Twilight finally gets to her feet next to you. “You could have just said stop, Anon.”
“I didn’t know if you’d hear me; you were flagging. I think we’ve done enough experimentation for one day.”
>The two – three; Octavia’s put her instruments down and stands near your controls and dropped notepad – ponies watch you as you stand and inspect the machine. You check the rubber flap near the weights. The thing’s absolutely shot. How it lasted this long you don’t quite understand.
“I don’t think we could have gotten much more out of it anyway.”
>You return to Twilight and Celestia. They didn’t appreciate that close call, you felt. Maybe you really were jumping at shadows. But if you overstated the risk, Celestia may demand you stop your work.
“I’m sorry, Princess, for dragging you out here. I’m sure you have better things to do with your time. Twilight, thank you for your help. You were great. I’ll send you everything I have once I’ve made a copy.”
>The two look at each other, and then back to you. Twilight cracks a smile. “Despite the abrupt end, if you got good information, the effort was worth it. I’d be happy to work with you again.” She looks back at Celestia, with the last few words.
>Celestia looks between you and Twilight several times, worry still plain on her face.
“She would make a great assistant.”
>Your mumble barely reaches her ears. After a few more moments, she flashes a resigned smile.
“I was wrong, Anon. It seems Twilight would be a good fit after all. But if you’re going to work with her, I insist on being more mindful of safety. If something were to happen to her – or to you – I would be quite cross.”
>Now it’s your turn to smile.
“Yeah, I’ll do that. Thanks.”
>”And,” Celestia says quickly, “I insist on being present, if you ever have to take work out of your shop again. If there are risks, I wish to know about them. It’s my job to know any threats to my ponies.”
“Yeah, of course.”
>”Now,” she says, looking over you two and Octavia.
>You stumble when the machine beside you suddenly blinks out of existence with a golden flash.
>“If we’re done here, how about some refreshments?”