October brought the first real cold snap to Hogwarts, and with it, a new problem for Eliot to solve.
The castle's heating system was ancient and inconsistent. Some rooms were swelteringly hot while others remained frigid. The Ravenclaw dormitories, located in a tower, were particularly susceptible to temperature fluctuations.
"I can't concentrate when my fingers are numb," Terry complained one evening, trying to write an essay while wearing gloves.
"And the common room is so hot you could roast a chicken," added Anthony, who'd stripped down to his shirt despite the October chill outside.
Eliot looked up from his Transfiguration homework, an idea forming. "What if we could control the temperature ourselves?"
"How?" Michael Corner asked. "We can't exactly rebuild the castle's heating system."
"No," Eliot said slowly, "but we could create localized climate control."
---
The concept had been percolating in his mind since his early experiments with runic circuits. Temperature was just energy—heat was molecular motion, cold was the absence of it. If he could create runes that absorbed or released thermal energy...
He pulled out his notebook and began sketching.
"Another invention?" Susan asked, settling into the chair beside him. Their torchlight business was thriving—they'd sold thirty units and had orders for twenty more.
"A heat controller," Eliot explained. "Something that could warm or cool a specific area without affecting the rest of the room."
Susan studied his preliminary sketches. "Like magical air conditioning?"
"Exactly. But more efficient and more precise."
---
The theoretical framework was complex. Eliot spent hours in the library researching thermal dynamics in magical systems, studying everything from fire-making charms to ice-preservation spells.
The breakthrough came when he found a reference to "thermal equilibrium runes" in an obscure text called *Advanced Environmental Enchantments*.
"Look at this," he told Susan excitedly, showing her the passage. "These runes don't create heat or cold—they redistribute existing thermal energy. They can pull heat from one area and concentrate it in another."
"So you could cool the common room by transferring its excess heat to the dormitories?"
"Theoretically, yes. But I want to start smaller—a personal climate control device."
---
The first prototype was about the size of a pocket watch, with runic circuits etched onto thin copper discs. The design was elegant in its simplicity: one set of runes absorbed thermal energy from the surrounding air, another set released it in a controlled manner.
"The beauty of this system," Eliot explained to Professor Flitwick during one of their regular meetings, "is that it doesn't create or destroy energy—it just moves it around. Much more efficient than traditional heating or cooling charms."
Flitwick examined the device with his magnifying glass. "Fascinating work, Mr. Clarke. The thermal regulation matrix is particularly clever. Have you tested it yet?"
"That's tonight's project."
---
The test took place in an unused classroom, with Susan as his assistant and witness.
"Remember," Eliot said, holding the prototype carefully, "if this goes wrong, it could either freeze us solid or set the room on fire."
"Comforting," Susan replied dryly. "Are you sure about the safety runes?"
"Reasonably sure. The fail-safes should prevent any catastrophic energy release."
He activated the device with a gentle touch of his wand. For a moment, nothing happened.
Then the air around them began to warm noticeably.
"It's working!" Susan exclaimed.
Eliot adjusted the control runes, and the temperature shifted from warm to pleasantly cool. Another adjustment brought it back to neutral.
"Perfect," he breathed. "The thermal redistribution is stable, the control response is smooth, and the power draw is minimal."
They spent an hour testing different settings and configurations. The device could create a comfortable microclimate in a sphere about six feet in diameter—perfect for personal use.
---
Word of the heat controller spread even faster than news of the torchlight had.
"You mean I could actually be warm in Potions class?" asked a Hufflepuff second-year who'd heard about the device.
"Or cool in Herbology during summer term?" added a Gryffindor.
Within days, Eliot had a waiting list of fifty students wanting their own heat controllers.
"We're going to need to scale up production," Susan said, looking at their order book. "And maybe raise our prices."
"The materials are more expensive than the torchlights," Eliot agreed. "Copper discs, thermal-conductive inks, precision runic etching... I'd say eight Sickles per unit?"
"Make it ten," Susan suggested. "This is genuinely revolutionary technology. Students will pay premium prices for personal climate control."
---
The success of the heat controller caught the attention of the faculty.
Professor McGonagall stopped by the Ravenclaw table during dinner one evening. "Mr. Clarke, I understand you've invented some sort of temperature regulation device?"
"Yes, Professor. A personal heat controller using thermal redistribution runes."
"Impressive. Professor Dumbledore would like to see it, if you don't mind."
Eliot's heart skipped. The headmaster wanted to see his invention?
"Of course, Professor. When would be convenient?"
"Tomorrow evening, after dinner. His office—password is 'Fizzing Whizzbees.'"
---
Dumbledore's office was exactly as Eliot had imagined: circular, filled with strange instruments, portraits of former headmasters, and Fawkes the phoenix perched on his stand.
"Ah, Mr. Clarke," Dumbledore said warmly, his blue eyes twinkling behind half-moon spectacles. "Please, sit. I understand you've been quite busy with inventions."
"Yes, sir. I enjoy applying magical theory to practical problems."
"A noble pursuit. May I see this heat controller I've heard so much about?"
Eliot handed over the device, explaining its operation and underlying principles. Dumbledore listened intently, occasionally asking perceptive questions about the runic matrices and energy conservation.
"Remarkable," the headmaster said finally. "You've essentially created a magical heat pump—a concept that eluded wizarding engineers for centuries."
"Thank you, sir."
"Tell me, Mr. Clarke, what drives this passion for invention? Most students your age are content to learn existing magic, not create new applications."
Eliot considered his answer carefully. "I suppose I see magic as a tool, sir. Like any tool, it can be improved, refined, made more useful. There's so much potential that hasn't been explored."
Dumbledore nodded thoughtfully. "Indeed. Magic is not static—it grows and evolves with those who wield it." He handed the device back. "I have a proposition for you."
"Sir?"
"The castle's heating system, as you may have noticed, is somewhat... temperamental. Would you be interested in designing a more comprehensive climate control solution? With proper supervision and resources, of course."
Eliot's eyes widened. "You want me to help redesign Hogwarts' heating system?"
"I want you to think about it. Such a project would be excellent preparation for advanced magical engineering studies. And the castle would benefit greatly from your innovations."
"I... yes, sir. I'd be honored to work on something like that."
"Excellent. We'll discuss details later in the term. For now, continue your current projects. You're doing remarkable work."
---
Walking back to Ravenclaw Tower, Eliot's mind raced with possibilities. A castle-wide climate control system would be an enormous undertaking—but also an incredible learning opportunity.
He found Susan in the common room, working on their latest batch of heat controllers.
"How did it go?" she asked immediately.
"Dumbledore wants me to help redesign the castle's heating system."
Susan nearly dropped the runic etching tool. "He what?"
"As a learning project. With supervision and proper resources."
"Eliot, that's... that's incredible! You're talking about magical engineering on a massive scale."
"I know. It's exciting and terrifying at the same time."
They worked in comfortable silence for a while, each lost in their own thoughts. Finally, Susan spoke up.
"You know, we're going to need a proper workshop soon. Somewhere we can work on larger projects without worrying about setting the dormitory on fire."
"I've been thinking the same thing. Maybe we could ask Professor Flitwick about using one of the unused classrooms?"
"Or," Susan said with a mischievous smile, "we could find our own space. I've heard rumors about a room in the castle that appears when you really need it..."
Eliot raised an eyebrow. "The Room of Requirement?"
"You know about it?"
"I've read references in some of the older texts. A room that becomes whatever the user needs most."
"Exactly. If we could find it..."
"We'd have the perfect workshop," Eliot finished. "Private, secure, and customizable to our needs."
They looked at each other and grinned.
"Road trip?" Susan suggested.
"Road trip," Eliot agreed.
Their little business was about to get a major upgrade.