After writing the two words "waterwheel", Liu Tan was stunned.

In his impression, this thing is actually a very good agricultural irrigation tool.

However, the greater function of the waterwheel is to reduce the irrigation difficulties caused by the height difference. Historically, it was used in the State of Shu after being perfected by Kong Ming.

The terrain of Shu Kingdom does require this kind of waterwheel, but the Northern Border Kingdom does not need it because most of the Northern Border Kingdom, or most of the arable land, is on plains.

So the waterwheel wouldn't be used for the time being, and Liu Tan hadn't thought about it before.

Unexpectedly, he built the waterwheel not for the development of agriculture, but to build a playground for Liu Che.

He sighed. Anyway, when Liu Che came, he could tell him the function of the waterwheel. Moreover, with the real thing, Liu Che should be able to understand the operating principle of the waterwheel better.

It was only when we were actually designing the waterwheel that we realized a problem: even if the water in the swimming pool is changed frequently, the water in the swimming pool is actually stagnant, which means that the water in the pool does not flow.

In the conventional impression, water wheels are mostly driven by water flow, but the pool does not have this condition.

Because the pool can be used for swimming, the canal cannot be built outside to allow the waterwheel to be driven by the water power of the Yellow River. In that case, what will be brought in is unfiltered Yellow River water. What is the point of all the filtering?

Thinking of this, Liu Tan couldn't help but sigh. Water power drive was out of the question, so the only option was probably animal power drive.

There are two options for animal-powered waterwheels: the traditional wheel-shaped waterwheel and the keel waterwheel.

The so-called keel waterwheel is a waterwheel with a scraper and a water bucket in the middle. It is long and narrow, with one end immersed in water and the other end rotated by an axle. When the water bucket on the waterwheel flips to the bottom, the water flows out of the water bucket, thereby achieving the purpose of bringing the water from below to the top.

This waterwheel is named keel waterwheel because its shape resembles a keel.

Most of the earliest keel water wheels were actually human-powered, including pedal wheels and hand-cranked wheels.

Liu Tan didn't want to use manpower, but it would be impossible to transport the cow to a height of ten meters and walk in circles on it using animal power.

There is no need to worry about transporting cattle, but whether the cattle are willing to move when standing so high is another problem.

In this case, the keel waterwheel is suitable, but it is not acceptable.

Then the traditional waterwheel needs to find a suitable driving force for it.

Liu Tan thought about it and it didn't seem that difficult. The wheeled waterwheel could be moved by using the continuous engagement of gears to transmit motion.

However, its cost may be several times that of a keel waterwheel.

But the problem is that Liu Tan does not need to reduce the cost as much as possible. If it is used by ordinary people, then it goes without saying that the keel water wheel is definitely better.

But he wanted to build an amusement park for Liu Che. Apart from anything else, the most important thing was that it looked good.

From Liu Tan's aesthetic point of view, the wheel-shaped waterwheel is more beautiful.

Apart from anything else, the sight of a round wheel standing there and spinning non-stop from a distance looks spectacular.

Unfortunately, animal power is also limited, otherwise Liu Tan would have to build a Ferris wheel.

As for where to arrange the gears and how to make the waterwheel look the best, Liu Tan said that these were not things he needed to consider. It takes a thousand days to train an army and only a moment to deploy it. This was when the Gongshu family needed to step in.

The Gongshu family has actually not been idle recently and has been cooperating with Xu Lin.

Although their family's main achievements are in the field of mechanical engineering, water conservancy machinery is also one of their research directions.

So when Xu Lin was undecided about some things, the Gongshu family could provide the answers.

Many people found the collaboration between these two people strange, but Liu Tan was very calm.

However, the Gongshu family only sent a few little guys out to follow Xu Lin to gain experience and provide help, but Gongshu Can stayed.

The reason why he stayed was because he was worried that if His Royal Highness the King of the North needed them and they were not there, something bad would happen.

As far as Gongshu Can knew, because the Gongshu family was doing very well in the Northern Border Kingdom, the Mohist school was also discussing sending people to the Northern Border Kingdom.

Gongshu Can felt extremely angry when he thought of this. They had already avoided the Mohist sect and were not active in places like Chang'an where there were many Mohist sect members. However, the Mohist sect still wanted to kill them all.

The Mohist school also felt a sense of crisis. The King of the North was not an ordinary prince. He had a profound influence on the emperor and the prince, especially when it was heard that he had given the prince another jade mine. Everyone in Chang'an knew that the King of the North was filial to his father and had a deep brotherly relationship with the prince. One word he said might be worth many words from others.

What if Liu Tan was pleased by the Gongshu family that day and spoke well of them in front of the emperor? What would happen to the Mohist school then?

Although the Mohist school seems to be doing well so far, in fact no one in a high position is willing to endorse them.

If Gongshu Jia could please the King of the Northern Territory, the replacement of their Mohist school would be imminent.

Not to mention that the King of the North seems to have some experience in mechanical engineering. It is said that many of the things Gongshujia has done recently were ordered by the King of the North, and he even gave Gongshujia the blueprints.

Even if the Mohists don't care about their own status, they still covet those drawings!

Gongshu Can felt more and more in a sense of crisis, but the things the King of the Northern Territory had been making recently had nothing to do with mechanical engineering, and his craftsmen could handle them.

Fortunately, he finally had a chance to use his skills. From the moment Gongshu Can received the task, he tried his best to make the waterwheel look better.

However, the transmission method of the waterwheel has basically determined many things, so no matter how sophisticated it is, the only surprises are in the details.

Gongshu Can's final choice was to paint patterns on the twenty-four wooden spokes of the waterwheel, and then the patterns on all the wooden spokes formed a huge... panda head when viewed from the front.

Fortunately, Gongshu Can did not make a waterwheel directly, but made a model.

After all, a waterwheel is about ten meters high. If he really starts to build it, it will be difficult to adjust if something goes wrong. The most important thing is that Gongshu Can also feels that he needs to ask their prince. The blueprint was given to him by His Royal Highness the King of the Northern Territory. He has never seen such a thing before and is afraid that there will be something wrong with it.

So Liu Tan felt a little uneasy after seeing the waterwheel with the panda head painted on it, especially when he saw the waterwheel turning and the huge panda head spinning up and down. He couldn't help but take a deep breath and asked, "Why did you come up with this pattern on the waterwheel?"

Gongshu Can said cautiously, "I saw that the pool designed by Your Highness was also in this shape, so... I wanted to echo it."

Liu Tan was silent for a while, looking at the rapidly spinning panda head. He felt a slight pain in his head for a moment, and sighed, "Let's change it."

At most, patterns were painted on the edges of the wooden spokes, but the wooden spokes themselves were not very wide. Finally, some lines were drawn on the center axis and edges with gold powder. It was not a special pattern, it just looked better from a distance.

However, it must be said that apart from the pattern, Gongshu Can did a good job in making the waterwheel. At least the model operated without any problems. He even built the entire water park according to the drawings given by Liu Tan.

Liu Tan took a look at the sand table and found that this water park was indeed similar to what he had imagined.

Originally, he was thinking about separating the slide and the pool.

But he also felt that there was no need for that. After all, no one would be so tactless as to play in the water while Liu Che was sitting in a kayak.

The entire slide is not directly above the pool, but a little to the side, and only the water inlet at the bottom of the slide is connected to the pool.

Liu Tan admired the sandbox and finally couldn't help but point to the stairs near the slide and asked, "What is this?"

Gongshu Can was puzzled and said, "Stairs? Shouldn't we slide down from them? We must go up them, right?"

Liu Tan was stunned for a moment, and only then did he realize that he seemed to have overlooked a very important issue - the height of the stairs.

The height of the slide is not low, about ten meters high, which means that Liu Che needs to walk up to this height by himself. This height is basically the height of a four-story building.

Think about it, his father has to climb four floors to play a water sport. If he wants to play it twice more, he will have to climb four floors a few more times.

By then, there would be no need for anyone to protest, and Liu Che would probably be the first to roll up his sleeves and deal with him.

Liu Tan looked at the staircase and said slowly, "Don't use the stairs, change it."

Gongshu Can had originally thought that stairs were inappropriate, so he carefully asked, "Then... what should we use?"

Liu Tan originally thought of building a spiral ramp and having people carry Liu Che up it, but he felt it was unsafe. Of course, the most important issues were the load-bearing capacity and construction period.

If a solid ramp is built, it cannot be too steep. If it is not steep, it will occupy a large area. Even if there are iron bars and cement, it will take a long time to build.

It is also necessary to ensure that the people carrying the sedan chair are stable enough. If they are not stable enough and it overturns, it will be a major accident.

Liu Tan looked down at the slide with a frown on his face.

Gongshu Can rarely saw him so worried, and for a moment he couldn't help but worry whether Liu Tan would cancel the project.

After all, if there is no way to go up, there is no need for the slide to exist, and the water wheel... seems to have no need to exist either.

You have to know that from the very beginning, the waterwheel existed to provide water flow for the slide.

Gongshu Can racked his brains but could not come up with a solution, but he gritted his teeth and said, "Your Highness, please give me some time so that I can come up with a better solution."

Liu Tan subconsciously asked, "What do you have in mind?"

When Gongshu Can was asked by him, he just wanted to fight for it, and of course he had no idea of ​​the method.

The only ways of transportation are human and animal power. Human power is dangerous and animal power is also dangerous. The most important thing is that those livestock are heavy, so load-bearing is also a big problem.

Liu Tan looked at him, smiled, and said, "I do have an idea, but I don't know if it can be realized."

Gongshu Can immediately said, "Your Highness, please tell me what you want to say. I will do my best to do it!"

Anyway, His Royal Highness the King of the Northern Territory never has unrealistic ideas. Even if the things he proposes are difficult, there are ways to solve them. There won't be a situation where it is completely unsolvable. Moreover, it is better if it is difficult to solve. Otherwise, how can it show that the Gongshu family is useful?

So now Gongshu Can is not afraid of difficulties, but is afraid of simplicity!

Liu Tan looked at him and said slowly, "Elevator."