Four days later, the merchant fleet raised its sails and departed from the dock.

Tasa, along with a hundred soldiers from the First Army, sailed with the ships, setting off for the royal capital.

In these days, Luo Lan and Magglida reached an agreement that Tasa could withdraw any amount of gold royals from her shop, which would be deducted from the sales of the steam engine. In addition, Luo Lan would need to pay an additional one percent interest.

This time, the amount of saltpeter and ore ingots brought by the other party was almost twice as much as last time, but even with the deposit for the renovation of the two inland river boats, Luo Lan still received over two thousand two hundred gold royals, which was an almost unimaginable number during the Months of the Demons. Even selling ore for a month would only bring in about three hundred gold royals.

After the merchant fleet left, Maisie also arrived at the day of temporarily leaving Border Town.

According to the agreement with Ashes, she would go to the Fiord Islands to bring news about the Western Region.

Luo Lan specially wrote her a long letter, expressing not only an attitude of mutual assistance and cooperation, but also hoping that the Fifth Princess could send some auxiliary witches to assist him. In the letter, he did not identify himself as her brother, but rather negotiated the matter as the lord of Border Town and the governor of the Western Region. Although the possibility of the other party agreeing was small, he still wanted to try—it wouldn't take much effort to write a few more words anyway.

The farewell location was in the backyard of the castle, and all the witches were present.

Nightingale gave her a small bag of dried fish slices; Lightning gave her a packet of pepper powder.

The other witches reluctantly stepped forward to stroke her feathers and hug her goodbye—the scene was almost like a final farewell.

"Don't worry, goo!" she raised her head and said, "I'll be back soon, goo!"

"What if Tilly doesn't let you come back?" Lightning said worriedly.

"Goo..." The pigeon shrank her neck and thought for a while, then shook her tail feathers, "Then I'll sneak back goo!"

"Then we have a deal," the little girl solemnly promised, "If you come back, I'll personally catch a bunch of birds and roast them for you to eat. And that beehive we found last time, we'll save it and take it out together when you come."

"Goo!" she nodded repeatedly, "Deal, goo!"

What else could he say? Luo Lan sighed inwardly. In just a month, he had completely won Maisie over to his side. Well done, Lightning!

"Then, goodbye everyone, goo!" Maisie spread her stout wings, ran a short distance on the ground before slowly taking off, circled twice, and gradually disappeared into the southeast.

"Will she arrive safely?" Luo Lan watched her slow movements and couldn't help but worry about her.

"No problem," Lightning said without hesitation, then tilted her head, "Should be... right?"

After sending off Maisie, Luo Lan quickly threw himself back into his busy daily work.

This time, he had to draw up a complete set of design drawings for the two ships left behind by the Crescent Moon Bay merchant fleet for renovation—and they would become the world's first paddle wheel ships powered by steam.

Since a single power source was used, there was no need for a gearbox, and the steam engine's power shaft could be directly connected to the paddle wheel. The speed could be controlled by controlling the amount of intake air through multiple intake pipes. To decelerate or stop the ship, simply close the intake pipe and let the excess steam vent out through the exhaust port. At this time, the fire in the furnace would still be burning, making it easy to accelerate again.

The principle was not difficult, and Luo Lan quickly drew a rough model. To obtain accurate production drawings, he would have to go to the site to measure the specific dimensions.

At this moment, Anna walked into the office holding a book.

"What's wrong?" He put down his quill pen and couldn't help but smile.

"I've finished reading this one," she placed the book on the desk. It was "Foundation of Natural Science Theory".

Luo Lan's smile froze on his face. This was too exaggerated. She had read all of the high school level math and physics knowledge in just a few months? He didn't ask her if she understood it, because Anna's reading meant complete understanding, otherwise she would definitely read it repeatedly or come to ask him questions.

"These drawings you've made, are you thinking of using a steam engine to replace the sails to provide power to the ship?" Anna's attention was quickly drawn to the sketches on the table, "But..."

"But what?"

"These two wheels are similar to oars, right? They can generate thrust when they rotate, but half of them are exposed outside, which is equivalent to wasting part of the power. Why not bury them all in the water?"

"..." Luo Lan was stunned and didn't know what to say. It was impossible for someone to be born with knowledge, which meant that she had made the above judgment based solely on this momentary impression? He suddenly became interested, "Then what do you think would be better?"

Anna thought for a while, picked up a pen, and began to draw on the paper.

Luo Lan supported his chin and watched her intently as she drew, her bangs slipping from her hairpin and swaying back and forth with her movements, her long eyelashes fluttering from time to time, and her fair cheeks revealing a natural rosy glow. Although he could only see her profile from this angle, the outline from her nose to her chin and then extending to her neck formed a perfect and soft curve in the light.

"Want to eat fish slices?" Nightingale leaned over and inserted her hand between the two of them.

"Yeah," Anna nodded, holding the snack that the latter handed over, "Thank you."

Luo Lan coughed twice as his line of sight was blocked, and he had no choice but to shift his gaze back to the drawings on the table.

At first, Anna tried to completely bury the paddle wheel in the water, but this would make it difficult to observe the position of the wheel when the ship was docking, making it easy for it to hit the dock or pier.

Then she placed the paddle wheel at the stern of the ship - this was also a common practice, but the transmission setup was much more complicated. After all, the bulky steam engine was not suitable for placement at the end of the hull, so the drive shaft and gearbox would take up a considerable portion of the hull.

And when Luo Lan saw the new drawings she had drawn, he couldn't help but marvel again at her keen thinking ability.

The sketch that Anna was working on was infinitely close to the arrangement of a single-shaft propeller. The steam engine was set at the bottom of the hull, and the drive shaft extended out of the hull below the waterline, with four square blades connected to the end, looking a bit like a windmill.

"I don't know if this will work," she hesitated, "Logically, as long as the blades are kept at an angle of inclination, they can generate a horizontal component of force, but I've reduced a paddle wheel, and relying on four blades alone may not be able to propel the hull."

"Of course it can, just make a few minor modifications." Luo Lan took the quill pen from Anna's hand and drew the original shape of the propeller, "Compared to the windmill shape, this shape of the blade is more suitable for rotating in water. Your thinking is completely correct, but the requirement in the contract is to convert it into a paddle wheel ship, so we'll still do it according to the first method - this has nothing to do with technology, but is a business strategy." He paused, "I'm going to measure the hull data now, would you like to come with me?"

Anna blinked her blue eyes, "Yeah!"

After mastering the theory, verifying it in practice is the best way to learn.

...

"Nightingale?"

Anna followed the prince to the door and couldn't help but speak when she saw Nightingale still looking at the drawings on the table.

"Ah, you guys go ahead, I'll be right there."

After comparing the sketches in her hand repeatedly, she came to the conclusion: Isn't it just changing the location of the wheel? (。).)