Act Two - A Black Comedy

Tales of Summer

The Tale of Hermione

The TARDIS was truly a wonder of magic. Oh, she knew she was fangirling about it, but Hermione really could not possibly care less. This was what magic was supposed to be about, not fighting wars, dispatching Eldritch monsters, or struggling desperately to survive.

Not that she really minded that aspect of her life in the abstract sense. No good story was without conflict of some kind, and in the story of her life, she would much rather be battling giant monsters and dark lords than, say, acting emotionally and intellectually challenged over some boy not worth her time.

That said, with all the excitement, studying, and danger, it was often hard to deal with the little things – little things like looking behind mysterious doors in the TARDIS. Hermione knew the room before her was part of her original floor plan. It was supposed to be there. But it also occurred to her that she’d not been inside it nor even seen past the door since the initial furnishing at the start of summer. Curious.

Hermione opened the door. Behind it resided a workshop. Tables, chairs, and crumpled up balls of discarded paper littered the room in equal measure to all manner of miscellaneous junk and simple enchantments. On display in a corner, a perpetually running model waterfall grew out of the ground as the crowning masterpiece.

A smile worked is way onto Hermione’s face.

I am going to tease Harry about this for years. A whole room dedicated solely to runecrafting. Brilliant! I wonder what he's been working on.

Poking around at the work Harry had archived, Hermione found only odd trinkets of little interest. Still, for not having an instructor, Harry had proven to be a surprisingly deft hand a rune crafting. She first deciphered the runes creating and destroying the water in the waterfall before then moving on to the next novelty.

And that was where Harry eventually found her. Hermione held a faintly glowing mammoth of an enchantment in her hands that, as far as she could tell, accomplished nothing more than creating light as inefficiently as possible. Such a curious thing it was.

“Oh. It's you.”

Hermione turned to regard Harry and raised her eyebrows questioningly at his rather restrained and flat greeting.

“Go ahead and get your jokes and ‘I told you so’s out of the way.”

“Not now, I think. I already had the privilege of the latter at the start of our break. The former I'm saving for more appropriate moments. I like your fountain.”


“Would you explain what you were hoping to accomplish with this…device?” Hermione held up the nightlight for lack of a better name.

“Oh. So much for the grand reveal…”

“I could put it down and forget?”

“No, it's fine. I was just hoping for a dramatic moment when I could make myself seem really smart.”

Hermione set the device down and crossed the distance between her and Harry to hug him. “Everyone in this house already knows you're smart. I'm very sure I'm the one who convinced you of that.”

“I suppose. So you want to know what this is?” Hermione followed Harry's finger to the nightlight before nodding. “Originally it was a supposed to be a magic sensor. Basically a magical voltmeter.”

“Thaumometer,” Hermione corrected. The thaum was not a unit of measure in the magical world, but it was the only correct choice.

Harry quirked an eyebrow but said nothing more. He pointed to the rune cluster at the bottom providing power. “When I read about passive absorption of ambient magic as a power source, the textbook noted that the runes would provide more power in places with more magic. The natural first thought from a mundane science perspective, I think, is that this a way to measure magic.

“And you can. You can convert from the output lux to…uh, the thaum, since both quantities are directly related. But it didn't do quite what I'd hoped for. As it is, it shines reasonably brightly without blinding you at ward boundaries, where magic tends to be more concentrated and ordered, but the sensitivity is far too low for the human eye to spot smaller changes.”

Hermione's​ grin only grew and grew as Harry continued with his explanation. I do so like being right. Harry really is smart; all he ever needed was motivation, time, and individual attention to blossom. Sure, she could complain that he preferred projects and practical things while she enjoyed theory and experiments, but in all honesty, she suspected it was better that way for them both. With their interests combined, nothing would be beyond their reach.

Once Hermione had shaken off the warm feelings bubbling up in her chest, she considered Harry's device with a more appreciative look. “Sounds useful. But why didn't you make the runes capturing magical flux smaller if sensitivity is a problem?”

“I did.” Opening a cabinet, Harry withdrew a much smaller softly glowing stone slab and handed it off to Hermione. “This version works on a smaller scale. This part here amplifies the signal to get a more visible change but requires a more magically dense power source to function. I carved a battery here for that, you see. When properly powered, it’d be a mere lamp here. At Hogwarts, it would blind you.”

Hermione made the obvious suggestion. “Have you considered a limiter on the input or output for a maximum brightness?”

“Haven’t gotten to that chapter yet,” Harry said. “Anyway, with the larger version, I accidentally discovered something…eh, moderately useful. If you set a spell inside the absorption runes – for example, a transfigured object – the runes will eat at it until it destabilises and disperses.”

“It works as a counterspell!” Hermione asked.

“Yes, but before you get too excited, it only works on things a finite could counter. That and smaller rune systems.”

“Oh,” Hermione said, her excitement leaving her as quickly as it had come. “It’s still neat. Actually, I think you've reinvented the basic framework of an artifact aurors use. Tonks wears a small earring that lets her know when she approaches a ward or when a spell is coming at her and from what direction. It can be fooled, but it’s a neat little device.”

A smile quickly lit up Harry's face. “Does that mean I do look really smart after all?”

Hermione rolled her eyes. “Yes, yes. You're brilliant.”

“I can't help but feel that wasn't genuine.”

Ignoring that comment, Hermione thought further on the small magic detector's possible uses. Few occurred to her, but being able to measure magic was the first step to properly analysing it. That was important in and of itself. But then the monumental truth struck her. She looked from Harry’s primitive thaumometer to his innocent face. He had absolutely no idea what he’d truly made!

“What is it?” Harry asked.

Hermione’s hands shook. She took a moment to settle her nerves. This was big.

“Harry, you made a device that amplifies a magical signal. This is a magical transistor.”

The boy clearly still had no idea what he’d done. The mundane transistor had revolutionised electronics and allowed for the invention of the modern digital computer. If these could be chained together the way Hermione expected…

“Would you mind if I used your workshop?”

Harry quirked an eyebrow but said, “Go ahead. Just clean up when you're done.”

Hermione turned to regard the state of the room. She looked back to Harry.

“By which I mean dump your mess in that corner if you don't want to get rid of it yet or vanish it.”

With that, Hermione shooed Harry out so she could focus without him distracting her. She apparently had far less practice than him at the actual carving of runes and wanted some peace and quiet while she worked.

The first thing Hermione did once she was alone was to carve out a few small, manageably-sized runic batteries. She filled them with magic and then set them aside to use later as inputs distinctly more powerful than the ambient magic of Crawley. As she had no hope of finding a magical vacuum to work in, she would have to tolerate the background noise.

After working out the maths necessary to determine how big and small she needed to make each part, Hermione duplicated two of Harry's magic detector's onto a single stone in sequence with one’s output feeding power to the next. The second output she left as a light rune that glowed dimly as expected. For her purposes, it would be considered off.

“And now the moment of truth.”

Hermione took one of her batteries and placed it near the runes absorbing magic on the first device, the first input. And as she wanted, the influx of magic did absolutely nothing. She moved the battery from the first device to the second. The result remained the same. Finally, she placed a second battery on the first input, and she grinned. The output light shined bright with magic allowed to flow through both transistors.

“I am brilliant,” she said, congratulating herself. I need to find a proper way to tell Harry how brilliant he is, too. After thinking about it for a few seconds, she placed the thought aside. She would ruminate on that matter later.

So I have an AND gate. All I need now is a NOT gate to be…be…be functionally complete. That’s the word. Words. Then I can build anything! I'm so glad Harry picked up that book on computers for us to browse through. If this works out, I need to find the time for both of us to read the whole thing.

So how do I build a NOT gate…

Not coming up with an immediate answer, Hermione left the workshop to fetch the book on how computers worked. As much fun as it would be to puzzle out the solution herself, she was more interested in quickly finishing her mini project. She opened the book to the right page and then promptly frowned.

It occurs to me that I don’t know how to read electrical diagrams.

Not deterred, Hermione turned back a chapter and set to reading. Once she was ready, she turned back to the circuit diagram for a NOT gate. Her frown returned.

This doesn’t work.

As it turned out, Harry’s device was not an exact analogue to a transistor. It more closely resembled a regular switch.

Okay, I still have an AND gate, and the OR gate implementation is obvious. I can chain these gates together so that one’s output can work as an input to another by adding a limiter to the input runes. That gets me a lot, right?

After thinking about it for half a second, Hermione knew she was wrong. She desperately needed an inverter if she wanted to create anything useful. Even an operation as simple as single bit addition required it.

Alright, Electrical Engineer Hermione, what do you recommend to fix this problem?

Define your problem first.

I need an input, when on, to output nothing and, when off, to output magic.

Simplify! Half of your problem is redundant.

Okay, I need an input, when on, to turn off an always on output.

The easiest way to do that would be to disable the rune cluster.

Hermione frowned. There was no ‘on/off’ rune. If there were, this task would be much simpler. There were runes to detect state, such as if water were nearby, but there were no runes to specifically enable and disable another rune cluster. To disable an enchantment, one simply cut the power – or destroyed an important rune.

So do that.

That… Hermione's attention fell onto Harry’s model waterfall. At its base, she knew he’d carved a rune cluster to destroy water. But at its source up above, there was another set of runes that created the water. That might actually work. If I set it up so that the input, when on, filled in a crucial rune, it could disable the output. The trick would be making it reversible. If I remember correctly…

Filling in a rune with stone was easy. She could easily repurpose the top half of Harry’s waterfall to do that. The problem came in later removing stone in the exact shape of the rune she filled in. It was doable. If she took the time, she could write down the entire runic array required to do so.

But it was inefficient, inelegant, and would require an enormous amount of time and space to carve. The direct approach would not do here.

Needing another book, Hermione left the workshop once again. She remembered reading in next year’s supplementary runes textbook about a runic array for this exact situation in a different context. From her bookshelves in her bedroom, she pulled down the book in question and flipped through it.

There was something in here… It wasn’t a ward. Those aren’t covered at all until the spring term of fourth year. I remember Dad making a joke about it… Hermione gnawed on her lip and looked up to the ceiling as she tried to recall what exactly her dad had said. It had something to do with his roleplaying games…

“Water traps!” Hermione said. “That was it.” There’s an array in here designed to temporarily fill empty space inside it with water. For pools or baths, not drowning intruders.

And indeed, as she flipped through the book, Hermione eventually found the example implementation she wanted. It filled a volume with water until the runes were deactivated. Without continued power or if the material left the affected volume, it and only it vanished immediately. Substituting the water material out for a generic stone would be easy enough.


Hermione returned to her project and set to work finishing her NOT gate. She first carved a power source that directly transferred magic to an output light. Naturally, the light was on. Next, she added the new rune cluster to fill in the single rune that performed the actual transference of magic from the source to the output. Without it, no magic would flow, and the output light would turn off. The other runes describing where to, where from, and how much did nothing alone.

Once Hermione was finished carving, she paused to appreciate her work, happy to have made a proper contribution of her own. There were probably better solutions to her problem, but this one would do for the moment.

And now to test her work. Hermione placed one of her batteries onto the NOT gate’s input. The light turned off.

“Yeeeessss! It works! It works!”

Now that she’d succeeded, the full implications of exactly what she had in front of her overwhelmed Hermione.

“Oh, Merlin! I can build a magic-compatible computer. That means I can create an index for Hogwarts’s library!”

Hermione paused. Maybe there were more important things a computer capable of interfacing with magic could do. A devious smile grew on Hermione’s face as she recalled a particular time her hand had cramped not too long ago.

“I could bypass every protection against copying on Hogwarts’s library books! The protections wouldn’t have the foggiest idea what was happening to the books if I did it right.”

That might also not have been the most optimal use of a magical computer – or even near optimal, in all honesty – but it was certainly a motivating use.

Hermione faked a cough. Right then. Step one on my quest to glory is obvious.

With paper and a pencil from her mokeskin pouch at hand, Hermione set about figuring out how she could add two one-bit numbers using logical ANDs, ORs, and NOTs. The task proved simple enough. She needed two outputs. The least significant bit needed to be on if and only if exactly one of the two input bits were on. That was perfectly doable. The exclusive or operation could easily be constructed from two ANDs, an OR, and a NOT. The most significant bit, the carry bit, needed to be on only when both inputs were on. An AND gate would cover that.

I’m going to have to carve hundreds of runes to make this work…

The task was simple but tedious. Even so, Hermione was resolved to see this proof of concept through to the end. She set to work carving.

Halfway through her task, a very disgruntled Hermione muttered to herself, “This is ridiculous. The first major runes project Harry and I work on is buying and setting up a mundane device to carve runes for us.”

Forty minutes later and about two hundred more runes into her project, Hermione considered that as soon as she got the very bare bones of a magical processor working, her first task would be to program it to punch out logical gates on demand along a grid. Unlike electrical wiring, runes could be placed much more haphazardly. Position only mattered in the sense that one had to know where to send magic to power other runes. There were no wires to clutter the design, and adjacency was a non-issue.

Finally, when she was at long last finished, a proud smile adorned Hermione’s face as she played with her very, very basic calculator. Never again would she have to add zero and zero, one and zero, or one and one.

Well, I’m entertained, at least.

“You know,” Harry said, causing Hermione to jump in surprise, “it looks like you’ve built a first class example of the major drawback of runes over spells.”

Hermione turned toward Harry and silently asked him what he meant.

“Time. Whatever you have there probably took ten-thousand times longer to make than an equivalent spell would be to cast. Hours versus seconds, and all.”

“But it’s reusable,” Hermione replied. “Make it once and you’re done forever.”

“Yep. Now what is that?”

Hermione grinned and turned back to her adder, demonstrating its functionality to Harry. She sensed that she appreciated it much more than he did.

“You do realise you're only half done, right?”

Hermione's face fell.

“I think the book we bought called this a half-adder. You need a third input for the carry bit if you want to chain a bunch of these together. Unless you just want to add one bit, of course.”

Hermione frowned.

“You need a pulse generator, too,” Harry added. “As I understand it, the clock is an essential component of a computer.”

“Can't we just enjoy the moment?” Hermione asked rather flatly.

“Sure. I am impressed. What you made is truly brilliant. But I did come up here to call you down for supper. It’ll be done in about ten minutes.”

“Fine, fine. Killjoy.”

“Perhaps, but I'm the killjoy who made your favourite dessert.”

Well in that case, all was forgiven. “I'll be down in a minute or two.”

Harry nodded and left. Hermione, too, left to wash her hands after tidying up her mess. At the door to the workshop, she stopped and looked back. A moment of indecision passed, and then she went back and took her adder with her.