Because the water park is not very close to Lianye Lake, Liu Che had only vaguely seen the waterwheel and the slide in front of the waterwheel before.

At that time he asked Liu Tan what that thing was, but Liu Tan wanted to keep it secret, so he didn't ask any further.

He just thought it was some kind of landscape building. However, when they set out for the water park, as they got closer, Liu Che realized that the wheel he saw yesterday was actually extremely huge.

He was in a good mood today, so he rode a horse directly instead of taking a car, so the experience was more direct.

When he could vaguely see the pool, he discovered that the huge wheel was still turning, and he could even see water falling from it.

The falling water all washed down the slide, and Liu Che couldn't help but ask, "What is that?"

Liu Tan said, "Waterwheel!"

Liu Che repeated the name of the waterwheel and asked in surprise, "How does this waterwheel... turn?"

Liu Tan pointed to the cows circling below and said, "It's powered by animal power."

Liu Che was so focused on looking at the huge waterwheel that he didn't even look down. Only then did he vaguely see the yellow oxen circling around the axle below.

Because of the slide, Liu Che couldn't see the entire waterwheel, so he simply said, "Let's go and take a look at this waterwheel first."

Liu Tan certainly had no objection, but he ordered his men to set up camp ahead.

Liu Che was a little surprised after hearing this and asked, "Didn't you say we weren't going to camp here today?"

This place is not too far from the tree house, so there is still time to go back and live in the tree house.

Liu Tan laughed and said, "Father, don't you need to change clothes before you go into the water?"

Liu Che hadn't swum for a long time, and at this moment, looking at the water in the pool that was faintly translucent with a hint of light green, he was actually quite moved.

Liu Tan leaned over and said, "The water in this pool has been filtered through several processes. It's very clean!"

"Filter?" Liu Che felt as if he had heard a new word and couldn't help asking, "How do you filter?"

Liu Tan said, "Because the water is diverted from the Yellow River, it's bound to have silt and other things in it. So, first, we use fishing nets to keep the fish and large aquatic plants out of the canal. Then, we filter it through gauze, adding a layer of gauze with each filtration. By the end, almost all the silt has been filtered out. Finally, we use alum to purify the water, and it should be very clean."

Even someone like Liu Che, who lived a refined and neat life, couldn't help but be stunned when he heard about this filtering method. This is just water used for swimming, and it also needs to be filtered like this?

In response to Liu Che's question, Liu Tan said confidently, "Of course, when you go swimming, it's inevitable that the water will get into something fishy. If it's not clean enough, it's easy to get ulcers."

After hearing this, Liu Che laughed, but did not scold Liu Tan for his extravagance.

Because he knew that Liu Tan's extravagance was usually used to buy him delicious food and fun things. This time, Liu Che also took a tour of the Northern Border Palace. Unexpectedly, the Northern Border Palace looked the same as last year. Except for some furnishings that changed with the seasons and were replaced for summer use, the rest was basically unchanged.

So Liu Tan's extravagance was never spent on himself.

The other princes' daily lives were already very luxurious, and when they welcomed the emperor, they were just a little more luxurious.

While chatting and laughing, everyone had already arrived under the waterwheel. The water flow from the waterwheel made a pleasant sound. Liu Che rode on his horse and looked at the yellow ox for a long time, and then watched the waterwheel turning for a long time.

Liu Tan leaned over and said, "Father, this waterwheel is also very useful for irrigation."

Liu Che understood what Liu Tan meant without him explaining it. The waterwheel could bring water to higher places, which was indeed more convenient in places with height differences.

After all, not all of the Han Dynasty's arable land is located on the plains.

However, Liu Che looked at the oxen and shook his head, saying, "Oxen are too valuable to be used to pull water carts."

The most important thing is that no one would be willing to use the ox to pull the truck, and the government would not pay for it. Even if the government took responsibility, it would have to send someone else to guard it day and night, otherwise the ox would be stolen on the first night.

Liu Tan said with a smile: "I use cattle because the water here is basically stagnant and can't flow. If there is water flowing near the river, I can use the water flow to push the waterwheel to rotate on its own."

After hearing this, Liu Che's heart moved: "Is it feasible?"

Liu Tan nodded vigorously. "It's feasible. I have already had a waterwheel set up by the river. If Your Majesty doesn't believe me, you can go and see it."

Agriculture is the foundation of the Han Dynasty today, and irrigation is the foundation of agriculture, so Liu Che put aside his thoughts of having fun and planned to go and take a look.

Liu Tan immediately asked someone to lead the way. They rode their horses at full speed until they arrived at the bank of the Yellow River. Sure enough, there was a waterwheel standing on the bank.

However, this waterwheel was much smaller than the previous one. Liu Tan explained, "It's not easy to build a large waterwheel. Since this area is all plains, we only need to dig canals to divert water, so we don't need a waterwheel. So I had someone build a small waterwheel for you to observe."

—Pedestrians were led to a very suitable location for viewing. From a distance, they could see only a waterwheel in the water, with nothing underneath. However, as the Yellow River flowed, the waterwheel kept rotating, and the water was brought up and then sprinkled from mid-air. It looked like it really did not need anything else to drive it.

Liu Che looked at it for a long time and nodded: "It is indeed a good thing, but such a waterwheel must have cost a lot, right?"

This question stumped Liu Tan. Liu Tan basically didn't have to think about the price when he made things now. He had too much money to spend anyway. Not only did he use the best materials, but he also paid workers very high wages and various welfare standards. As a result, many people who came to work asked His Royal Highness the King of the North when he would continue to build things after the work was completed.

Many of these people were refugees who had drifted here due to the snow disaster. Under the strong suppression of Liu Tan or Huo Guang, these people could only work in exchange for relief. But after this work, some of them were even able to rent houses in Shuofang City or buy small plots of land in the surrounding villages and towns to build houses!

In this situation, Liu Tan certainly wouldn't care about how much money was spent. Fortunately, Miao Rui and Bi Gao were by his side. Bi Gao stepped forward and said, "Your Majesty, this waterwheel cost about 100 strings of cash, and the one just now cost about 300 strings of cash."

The price of a waterwheel does not double when its size doubles. Generally, the price doubles when the height increases by one meter.

First of all, it is difficult to find whole logs of this height, and secondly, the larger the log, the more wood is needed.

After hearing this, Liu Che couldn't help but shook his head: "Too expensive."

Liu Tan said, "Actually, I think bamboo and wood should work just as well. However, bamboo doesn't grow in the Northern Territory. Even the bamboo that does grow in Gungun has to be carefully cared for to barely survive. Unfortunately, it's just alive; it's unlikely to grow. So, there's no way I can experiment with bamboo and wood. I'll send the blueprints to His Royal Highness the Crown Prince as soon as possible, and ask him to send someone to test it out."

Bamboo grows quickly, is easier to obtain than wood, and is easier to process. The only thing to worry about is that bamboo itself is very light, and it takes some effort to make it stand steadily in water.

The official next to him couldn't help but interject, "Since ancient times, most of the water that needed to be brought uphill has been from mountainous areas. Mountain areas are inherently poor, so even using bamboo and wood wouldn't be easy. Most importantly, there probably aren't skilled craftsmen like that in those areas."