According to the construction plan, Roland arranged an equipment room at each well point to accommodate all the devices required for the three-way connection, in order to facilitate management.

The complete set of equipment includes a steam engine, an electric motor, a power supply, a boiler, and two water storage tanks. Together with the water tower outside the room, it constitutes the entire three-way system.

The steam engine is responsible for pumping well water into the water tower and storage tanks. The former mainly provides domestic water for residences, while the latter prepares heating water for the boiler. The primary storage tank is located higher above the ground and contains limestone and washing stones suspended inside, which are used to precipitate magnesium and calcium ions in the water, resulting in water softening. The clarified water will be introduced into the secondary storage tank, which is located lower, and the floating objects in the water will be intercepted by Soraya's special filter screen.

The boiler's water supply is completed by the electric motor. When the internal water level is too low, it will drive the float valve to turn on the electric motor to supply water until the water level returns to normal. This process is much more stable than manual addition or steam engine transportation, and it also eliminates the trouble of needing someone to stand by and observe at all times.

Since the water supply and heating have both undergone early verification projects, there will naturally be no difficulties in this construction. The key lies in the power supply system, which is still a first for the town. Whether it is Karl or other members of the Stonemasons' Guild, they certainly know nothing about electricity. Therefore, Roland plans to first make a small-scale model in the courtyard, and then explain it to the Construction Department after success—after all, he doesn't know much about this aspect, and his knowledge of circuits basically stays at the high school level.

With a reliable and stable power supply, the first step should be to create a qualified electrical appliance, which is the light bulb.

Thinking of this, Roland put on a thick coat and set off for the backyard of the North Slope Mountain.

Traveling through Nightingale's mist, the journey that would originally take a quarter of an hour only took three or four minutes to reach the destination.

Pushing open the wooden door, Anna and Lucia immediately noticed him, but the former only nodded at him because she was busy with her work, while the latter ran over happily, "Your Highness, good morning."

"Good morning," Roland said with a smile, nodding. Then he walked to Anna's side, "What are you busy with?"

"New barrels and breech mechanisms," she pointed to several steel long tubes on the table seriously, "Your drawings are a bit unreasonable. I think it would be better to modify them like this."

Awesome, my Anna. Roland couldn't help but reach out to touch the other person's head, but was rejected by shaking back and forth. Hmm... this scene seems familiar. He coughed twice and restrained his teasing mood, "Well, do it according to your idea."

Roland didn't mind her questioning his design. The *qiangxiè* drawings themselves were inferred by him based on principles. It's normal to have flaws and room for improvement. What's more, Anna's own learning talent and comprehension ability far exceed his own. He thinks that one day, her understanding of knowledge will reach a height that he cannot reach.

After a while, Anna put down the finished parts in her hand and walked to Roland, bowing her head slightly.

Uh... Roland couldn't help but be stunned. Was she going to make up for the previous caress?

He tried to rub her soft hair, and Anna raised her head contentedly, "Do you have something new you want to try to make?"

"Ah... that's right," the prince looked at Lucia, "How are you doing with the separation of those messy ores in the mine?"

"Basically completed, the results are all here," the latter handed him a stack of notebooks, "However, the tests of mixing with steel may take a long time, because there are too many separated elements."

"It's already very good to be able to do this," Roland encouraged approvingly.

This is also an extension of the material improvement plan. Compared to the previous control of carbon content and removal of impurities to obtain high-quality steel ratio, the elements now involved have been expanded to the resources that the entire North Slope mining area can provide. There are not many clever things in this part, only a little bit of adding and trying.

Roland spread out the notebook and checked the characteristics of various unknown minerals in the stockyard, and quickly found the element with the highest melting point. He pointed to a column marked with experiment number twelve, "Where is this ore?"

Lucia then rummaged through the experimental samples—they were sealed in transparent coated bags, one was an ore and the other was a package of decomposed elemental particles.

And that dark ore, Roland felt like he had seen it somewhere.

Wait, isn't it the same as the black stone that was sent to his office before? Since he handed it over to the alchemist for processing, he also left the matter behind and never paid attention to its news.

It turned out to be the mineral with the highest melting point in the North Slope Mountain?

In the notebook, Anna couldn't make precise marks on the specific value of the melting point, so she could only use language to describe it. Among the ordinary, high and higher, only its characteristic column was written as extremely high.

As for that package of elemental particles, it was silver-white like most metal elements, and there was nothing different.

Could this thing be tungsten?

But whatever, as long as it's refractory.

Roland asked Anna to process it into extremely thin metal wires, twist them into a spiral shape, fix them on a glass stand, and then put the stand into a glass bulb. The main part of the light bulb was completed.

Of course, if you want it to glow stably, there are still two steps to do—and this is also the most difficult part of the light bulb process: one is to evacuate the air, isolating oxygen from reacting with the filament; the second is to seal, ensuring that air does not enter the bulb.

There is no doubt that only witches can do these two steps.

Roland first found Agatha.

Vacuuming is mainly because the filament becomes extremely active at high temperatures and is prone to oxidation reactions, generating new oxides. The result is burnout. To achieve this effect, filling with a non-reactive gas is also effective, even better.

Pure nitrogen is an excellent filler.

Using the principle that nitrogen is lighter than air, a simple downward exhaust method can easily fill the bulb with nitrogen, which is much simpler than the vacuuming step. When the gas discharged from the other end is also nitrogen, Soraya is responsible for sealing it, and a simple incandescent lamp is completed.

Looking at the palm-sized light bulb in his hand, Roland was filled with emotion. Such a thing that has been eliminated in later generations now represents the highest production level in the town.

The next night, he summoned all the members of the City Hall to the castle forecourt, and at the same time ordered the guards to extinguish the torches in the courtyard.

In the snowy night where dusk covered everything, Roland closed the circuit switch.

In an instant, an orange-yellow light lit up in the center of the courtyard. It did not sway and go out in the cold wind like candlelight, nor did it flicker like a bonfire. The illuminated range was not large, only a few meters around, but the stable light standing against the wind was a sight that people had never seen before.

No explanation is needed at this time.

People's unwavering expressions and the quiet scene explained everything.

He brought electricity to this world.