Chapter 78
After fourth period ended, lunchtime arrived.
With Seori and Yuna snarling at each other, we lined up for lunch with Jihye.
Everyone was busy talking about the performance assessment from that morning.
Jihye clapped her hands together.
“Your class competed with numbers too! Our class's record was 9.3.”
“It was such a close call, Jihye! I got over 9 at the very end too!”
“Then who got first place? Was it Name, as expected?”
“Ahem...!”
“...?”
Yuna proudly raised her chin and snorted.
“Name did everything for you.”
Seori shot her a sour look.
Yuna's energy had been sky-high since the end of second period, and it showed no sign of fading.
Seori had already heard the details once, so she told Jihye the same thing.
“But injecting mana that precisely was really hard!”
“Yeah, yeah, you're amazing!”
“But how did Name figure out that number?”
Everything about the model magic circles was beyond the elementary-school curriculum. It might even have been middle- or high-school material.
It was only natural for Jihye to be puzzled.
“The one we received was a magic circle based on the harmonic mean. If the northern optimum is 150 and the southern optimum is 200, I figured the overall result would be around 171.42.”
“What's a harmonic mean?”
“Umm... How should I explain this?”
If I defined it as the reciprocal of the arithmetic mean of the reciprocals of the variables, she wouldn't understand.
At times like this, it was easier to explain things with simple numbers.
“What's the average of 1 and one-third?”
“Umm... Ummm... I know this. I definitely learned it, just wait!”
Jihye racked her brain and barely managed to come up with an answer.
“Three-thirds? No, that's 1! Two-thirds?”
“Ooh, our Jihye's so smart!”
“Aah, don't tease me when you already know!”
She coldly brushed away Seori's hand as she patted her head.
“This is how you calculate the harmonic mean. Answer my questions one at a time. What's the reciprocal of 1?”
“Obviously, 1.”
“Then what's the reciprocal of one-third?”
“Three?”
“Find the average of the two.”
“This one's easy. 2!”
“And what if you take the reciprocal of that again?”
“Umm... one-half?”
“Correct. That's the harmonic mean. Got it?”
“No, I don't understand any of it!”
I thought I had explained it simply.
As expected, I didn't seem to have any talent for teaching children.
If even simple math was like this, I had no idea how or where to start when it came time to teach Adela.
Anyway.
After receiving our food in order, we went to the far corner of the cafeteria and took our seats one by one.
As always, Seori sat beside Jihye, and Yuna sat beside me.
“Waaah, the bulgogi looks really good.”
Yuna set down her tray with a bright smile. Fortunately, today she had piled it high with rice and meat dishes.
“Are you only going to eat that little again today? Want me to share some of my meat?”
“I'm okay.”
“If you eat so little, you might get sick later.”
She was sick, so she could only eat a little.
Hoping Professor Cheon would soon bring good news about the potions, I put a piece of bulgogi in my mouth.
Unlike the usual nonstop chatter, today's atmosphere was completely quiet.
Seori and Yuna kept rolling their eyes around, as though they were thinking about the harmonic mean I had just explained.
Unlike Seori, who continued trying to understand it, Yuna seemed to have grasped it to some extent and asked me another question.
“I understand the formula. But I still don't know what that coil magic does.”
“Are you curious about the coil magic, Yuna?”
“No... Ah, yeah, I am curious, actually. Tell me...”
For once, Yuna lowered her head and asked me first.
She usually had a strong tendency to refuse to admit when she didn't know something, so she must really have been curious about that magic.
How could I explain it simply?
There were limits to explaining it with words alone.
“I'll tell you when I drink my potion later.”
As expected, there was no better way than showing her an example directly.
* * *
Formulas and theories were merely supplementary elements when it came to explaining magic.
Ultimately, understanding magic required a more intuitive observation of why such phenomena occurred.
I took Yuna to the school's back courtyard.
Beside the wall marking the boundary between the middle- and elementary-school sections, I set down one of the potion bottles I'd brought from our classroom.
“Why did you bring me here?”
“I came to show you some magic.”
“It's kind of scary because there's no one here.”
Indeed, unlike the garden in front of the main building, weeds grew thickly in the back courtyard.
They also helped create a creepy atmosphere.
But the reason I had chosen this place was that people rarely passed through it.
“Did you bring an old ballpoint pen?”
“Yeah. This one broke, so I don't use it anymore.”
I removed everything from inside the four-color ballpoint pen Yuna gave me, leaving only the plastic shell.
With that, all the preparations were complete.
“The model you saw earlier is magic that generates heat with electromagnetic coils. It won't be exactly the same, but I'll cast something as similar as possible.”
Before uncapping the potion, I drew the outline of a magic circle on the ground.
It would be difficult to understand from the appearance alone, but now I would channel the spirit of a top-tier lecturer and explain it as simply as possible.
“Something made by twisting wire around and around like this is called a coil.”
“I know what coils are! We learned about them in science class in first grade.”
“Oh, then this will be easy to explain. This part here is a formula that makes current flow through the coil.”
“Current?”
“I mean electricity.”
“It makes electricity flow? Why?”
“When electricity flows through a coil, it generates heat.”
“So the coil gets hot?”
“Yeah, incredibly hot.”
I skipped all explanations of voltage, current, and resistance.
For now, knowing only that a coil grew hot when current flowed was enough to understand the magic circle.
“What happens if water gets hot?”
“Umm... It becomes hot water?”
“Make it even hotter.”
“The water turns into steam!”
“Right. From now on, we're going to use the coil's heat to turn liquid into gas.”
First, I drew an engraving magic circle on the ground and linked it to the pen.
The part operated by an electromagnet was complicated, so I boldly removed it and modified the magic circle to supply ordinary electric current.
[Engraving: Heat Transfer–Coil]
I also added a pointer-linking circle so the inside of the pen would follow the principles encoded in the magic circle.
“Yuna, just imagine that there's a tiny coil inside the pen like this.”
“Mm-hmm.”
“What do you think will happen if we drop potion onto a hot coil?”
“Won't the potion turn into smoke? Or... maybe the coil will cool down?”
“The coil can't cool down, so I put cotton in the middle. We'll drip the potion onto that cotton one drop at a time.”
“Then it'll turn into smoke!”
Yuna said confidently, and I affirmed her answer.
As soon as I uncapped the potion, I inserted the pen into the mouth of the flask.
To keep the residue from oxidizing, I filled every remaining gap with clay left over from art class the previous week.
It made a ridiculous-looking structure, but there was no easier way to explain this magic.
“The key to this magic is resistance. Watch closely. If I inject mana here, the total resistance is 0.5 ohms, you know?”
Tap-tap-
I tapped the ballpoint pen twice, activating the engraving magic circle.
As soon as the magic circle on the ground lit up, I put my mouth to the end of the pen and drew in a sharp breath.
The potion was absorbed by the cotton and immediately vaporized by the heated coil, producing steam.
The gas passed from the pen into my mouth, from my mouth to my throat, and from my throat to my lungs. When I exhaled again, it billowed out as a hazy cloud.
“Hooooo.”
Just as expected. Taking the potion this way definitely reduced the bitter taste.
Moreover, mana in its nebula state tended not to escape once it entered the body, so in terms of efficiency, it was not much different from taking it as a liquid.
Why had I never thought of taking potions this way before?
It was a moment that made me realize once again how desperately creativity was needed in life.
“Waaaaah! How did you do that, Name? Smoke is coming right out of your mouth!”
“How about I double the resistance this time? Then twice as much smoke will come out.”
“Even more than this?”
Yuna looked excited, and her excitement lifted my mood too.
I changed the resistance to 1 ohm, put the pen in my mouth once more, and inhaled.
“Hooooo.”
“Whoa, smoke! Cough, cough...! Ugh, it's bitter.”
Yuna waved her hand through the smoke, which was nearly twice as thick as before, then coughed, apparently after inhaling some through her own nose.
“You shouldn't deliberately breathe it in. Do you want to try it too? This isn't bitter at all.”
“I nearly died when I took it wrong that time...”
Yuna shook her head vigorously.
If she didn't want to, I couldn't force her.
I hurriedly puffed out smoke to finish off the remaining potions before fifth period began.
Yuna, who had been watching how the magic circle worked, muttered to herself.
“But it really looks just like cigarette smoke.”
“You're really smart, Yuna.”
“Huh?”
“This works on exactly the same principle as cigarettes.”
“What?”
Exhaling the last puff, I finished my potion dose for lunch.
The engraving magic circle was said to last a long time, but apparently twenty uses was its limit, and no more heat could be expected from it.
“This is called an atomizer (vaporizer). It's a device found in e-cigarettes.”
Don't kids these days use e-cigarettes? Maybe they don't know what they are.