The sun had just cast its last rays, and the breeze by the river was a bit chilly. Chen Hao wrapped his coat tighter, still clutching half a piece of unfinished dry rations in his hand, munching on them as he walked, his cheeks puffing out.

He had just returned from the East Second Plot, his legs were still sore, but he felt great. Those new plows had been the center of attention today, surrounded by layers of workers, even the most disgruntled old hands had fallen silent. As he walked, he thought, if these things had some added functions, wouldn't they be able to take over people's work in the fields, eat, and sleep?

The moment the thought crossed my mind, my feet slowed down.

The river was right in front of us, its current neither swift nor slow, pushing a few withered leaves around in circles. A broken branch was stuck in a crevice in the shallows, its head and tail being pulled back and forth by the current, as if someone was pressing its shoulders and making it nod incessantly.

He stared at the branch for three seconds, then suddenly let out a loud "Ouch!" and almost spat out the steamed bun in his mouth.

"Oh dear, what an idiot I am!" He slapped his thigh hard, making the mark in his pocket jump up and down. "We have windmills to generate electricity, how could I forget about this thing?"

Before the words were even finished, the person had already turned around and run back, their shoes scraping against the dirt road with a crackling sound.

"Nana! Where's Nana? Come quick! Look at this water!"

Nana was standing at the workshop entrance, adjusting a terminal. Hearing the shout, she looked up; the metal casing gleamed coldly in the twilight. She didn't move, only speaking when he rushed up to her, panting heavily, "What are you yelling about?"

“Water!” he pointed to the river. “It’s always moving! Can we make a wheel so it can turn? Once it turns, it can power machines, and with machines, we can do the work, and we won’t need people to do the work—do you understand?”

Nana blinked, the screen lit up, and she started adjusting the data. "You mean using the kinetic energy of water to drive a mechanical device? Theoretically feasible. But we need to provide parameters such as the river width, average flow velocity, drop height, and load requirements."

Chen Hao froze, opened his mouth, then closed it again.

"...What did you say?"

“I said, if you want to build a waterwheel, you have to know first whether the river has the power to push it.”

"Oh." He scratched his head. "Then can you check?"

“Search has started.” She looked down at her computer and said, “Local topographic data shows that the river section is about four meters wide and has a stable annual flow. Based on recent rainfall records and slope calculations, the average flow velocity is 0.8 meters per second, and there is a natural drop of 1.2 meters downstream.”

She paused, then looked up: "The theoretical output power can reach 3.5 kilowatts. Enough to drive several small and medium-sized agricultural devices."

Chen Hao's eyes lit up immediately: "Really? That's amazing?"

“Real data,” she said. “If a low-speed, high-torque impeller structure is used, the energy conversion efficiency can be optimized.”

"I knew it wouldn't be a waste of time to see this river!" He grinned, pulled a marker from his pocket, and quickly drew a circle on a piece of discarded wood next to him, then added a few diagonal lines. "Look, the wheel is so big, the blades are stuck on the side, and when the water rushes through, it spins around with a whooshing sound—isn't that what it means?"

Nana leaned closer to take a look and tilted her head slightly: "Sketch recognition complete. This is the most basic impact waterwheel structure, suitable for high flow velocity and low drop scenarios. However, the current river section is more suitable for an improved crossflow design."

What style?

“Three classic types: bottom impact, middle impact, and top impact,” she said calmly. “They are classified according to the direction of water flow and the position of the impeller. Here, we recommend a modified crossflow type, with blades arranged radially. The water flow cuts in from the middle, driving the impeller to rotate, which is suitable for medium flow rates and stable drop.”

Chen Hao looked completely bewildered and waved his hand to interrupt, "Don't use these jargon, it sounds like a hospital registration office. Just say—can we transfer for a small matter?"

“Yes,” she said, “but the principles must be verified first. Directly building the physical structure carries the risk of wasting resources and cannot rule out potential problems such as structural imbalance and transmission failure.”

"I want to try something big."

"The cost of failure is too high."

"Just because the small one is spinning doesn't mean the big one is usable."

"But if you don't start with small things, the big ones will just become a pile of scrap metal."

The two stared at each other for a second.

Chen Hao sighed, "Alright, alright, I'll do as you say. Let's start with a small one."

He lowered his head and continued drawing, the tip of his pen crookedly sketching a wheel with a support, and then wrote "V1.0" next to it, leaving a long trail of ink at the end.

"Let's call it 'Waterwheel Prototype V1.0', and start working on it tomorrow!"

Nana scanned the graffiti on the wooden board and tapped the screen with her fingertip: "The sketch has been archived. The bill of materials and structural simulation will be completed tonight. It is recommended to prioritize making a scale model tomorrow to test torque output and stability."

"You actually take it seriously?" he laughed.

“You come up with the idea, and I’m responsible for bringing it to fruition,” she said. “That’s our workflow.”

“Yeah, right.” He patted his pants, stood up, stretched, and his bones cracked. “I used to never even copy homework, but now I’m starting to invent things. Life is so ironic.”

“Your enthusiasm is increasing,” she said. “Your daily activity level has increased by 47% compared to three months ago, and you’ve proactively suggested technical improvements 2.3 times a week.”

"So I've improved?"

"Data shows that you are gradually shedding the label of 'purely consumptive individual'."

"Thank you. I thought you were going to say, 'Congratulations on finally acting like a normal person.'"

That doesn't match the objective description.

He laughed heartily, grabbed the wooden plank, and headed towards the workshop: "Come on, let's put these precious blueprints away first. Tomorrow, when we start work, the first thing we'll do is find a good piece of wood to erect a memorial tablet for our waterwheel ancestor."

Nana followed behind him, her steps light and steady: "I suggest using lightweight hardwood to reduce rotational inertia. Also, reserve a gear interface for easy connection of simulated loads later."

“I’ll agree to whatever you say.” He pushed open the workshop door, and the lights inside came on. “Anyway, you can calculate faster than I can. I’ll just draw the circles, and you’re in charge of keeping it from falling apart.”

Inside, the workbench was neatly arranged with yesterday's plow testing tools, and an unopened box of parts was piled in the corner. He propped the wooden plank against the wall and casually added a note on the edge: "Don't let the rats gnaw on it."

Nana walked to the terminal, started the computing task, the screen flashed, and the 3D model began to be generated.

"The water flow simulation program is loading, and the first version of the plan is expected to be output before 6:00 AM tomorrow."

“Then don’t sleep too soundly tonight,” he said.

“I don’t sleep,” she said.

“Oh right.” He scratched the back of his head. “You don’t even snore.”

It was completely dark outside, and the faint sound of the river could be heard, like some kind of heavy breathing. He stood at the door, glanced back at the river, then at the sketch on the wall, and suddenly felt that even the wind tonight carried a hint of electricity.

"You know... if this thing actually starts spinning, could you also install a fan in my dorm room?"

“Yes,” she said, “provided that the fan power does not exceed the available margin.”

"What if I add a refrigerator?"

"Load balancing needs to be reassessed."

"What if I want to cook some instant noodles?"

"I suggest you give up your illusions."

He laughed out loud, leaned against the door frame, and gazed at the river in the night.

"Actually, I hated physics when I was a kid. I wanted to run away whenever I saw formulas. Now, I'm talking to you about torque, speed, and power every day. I feel like a fake scientist."

“You’re not a scientist,” she said. “You’re the one who asks questions.”

"So you're the one who solves problems? If we get together, we can barely be considered a team?"

"Currently, the collaboration efficiency is 78.6%." She paused, "There is still room for improvement."

"That's more than enough." He straightened up. "At least I didn't treat you like an instruction manual."

She didn't respond; instead, a message popped up on the screen: [Hydrological data analysis complete] [Model building progress 12%]

He yawned and rubbed his eyes: "Alright, that's enough for today. Come early tomorrow, I want to see this little wheel turn with my own eyes."

"A reminder has been set for 5:30 a.m.," she said. "The preliminary test plan will be pushed out at that time."

"You're even more ruthless than an alarm clock," he muttered as he walked out. "But... you're pretty reliable too."

Nana stood there, watching him leave. She tapped her metal fingers lightly on the table and muttered to herself, "Concept registration complete. The research and development phase has officially begun."

She brought up the new project panel and placed the cursor on the title bar.

After a moment, type five characters:

**Waterwheel Project: Initial Launch**

Outside the window, the river continues to flow.

A piece of driftwood drifted slowly by, hit a rock, and spun gently.