Liu Tan looked Lu Xuan up and down, thinking for a moment before saying, "I remember you should be able to swim, right?"

Lu Xuan said calmly, "Yes."

Liu Tan asked, "What do you wear when you swim?"

Lu Xuan was puzzled: "I'm not wearing it."

Liu Tan: ??????? !!!!!!!!!

He looked at Lu Xuan, who had broad shoulders, a thin waist, and long legs, and imagined that scene again. He couldn't help but feel his throat dry, and suddenly understood Lu Xuan's thoughts just now.

Seeing his surprised expression and eyes widening, Lu Xuan couldn't help but lean over and whisper, "What about you?"

Liu Tan didn't react for a moment and asked blankly, "What?"

Lu Xuan put his arm around his waist and asked, "What would you wear when you go in the water? A water jacket?"

Liu Tan came back to his senses, blinked for a long time before his face turned red and he managed to say, "I can't."

This is not false, he really wouldn't do that. In his previous life, the area where he lived from childhood to adulthood had never exceeded the north-south dividing line.

He didn't receive the memory of this body, and as a result, he was so busy that he forgot about this matter.

Lu Xuan was stunned for a moment before he chuckled and said, "It's okay. Do you want to learn? I'll teach you."

Liu Tan said sadly, "Where would I find the time? Forget it, if I can't do it, then I can't do it. Anyway, I don't need to accompany my father into the water."

Lu Xuan was somewhat disappointed. He had originally thought that he could teach Liu Tan how to swim and do some unspeakable things along the way, but now it seemed that there was no such opportunity.

Seeing him look downcast and remain silent, Liu Tan couldn't help but cough and said, "Wait until my father returns to Chang'an."

Lu Xuan immediately looked up after hearing this. His dark green eyes, filled with sunshine, fixed him intently as he asked, "Then... when?"

Liu Tan thought for a moment and said, "It seems like it will take at least two months. We have to get through the summer."

Lu Xuan: ...

Not to mention two months, he might have to go back to Wusun in a month!

Seeing Lu Xuan lower his head in disappointment again, Liu Tan found it quite funny and went over to kiss him. Just as he was about to make a few jokes, Lu Xuan grabbed the back of his head and gave him a deep kiss that almost made him suffocate.

After they separated, Lu Xuan hugged Liu Tan and gently stroked his back and said softly, "You haven't said what water support is yet."

Liu Tan, dazed, finally came to his senses after hearing this. He said in a slightly hoarse voice, "It's clothes made of fish skin. They allow you to swim more smoothly in the water."

Clothes made of fish skin...

Okay, Lu Xuan finally understood why he had never heard of it before. Such a thing could not be found in Wusun... let alone Wusun, it was impossible for it to exist in the Western Regions.

Every country is basically built on the basis of oases. There is water, but it is limited, and fish are even more limited. It is impossible to use fish skins in large quantities to make water vessels.

This also indirectly proves how extensive the resources of the Han Dynasty were. No wonder the Huns were always plotting against the Han Dynasty.

However, Lu Xuan did remind Liu Tan that he had previously thought that he had considered most of the problems, but ended up forgetting about the water.

Liu Che was on a northern tour this time and had no plans to go east, so it is very likely that he would not have thought about the issue of launching into the water.

Although he didn't know whether Liu Che had ever gone into the water when he went east, he couldn't write to Liu Che asking him to bring his own swimsuit.

So after much thought, he simply asked someone to prepare water.

In fact, Liu Tan knew about the water backrest, but he had never seen it before, so after instructing his subordinates to start preparing the water backrest, he found a set to study.

After taking it up, he found that it was very similar to the diving suits of later generations, but because of the material, it might not be so close-fitting, and not so soft, and the stretchability was a little worse, but for this era, it was already very good.

Lu Xuan curiously walked around the water bank, touched it with his hand, and then tentatively lifted his sleeve and put his arm inside.

Seeing his action, Liu Tan couldn't help but ask, "What are you doing? Want to try it? Then you have to take off your clothes."

Lu Xuan shook his head and said, "No, I just think it's too inconvenient to swim in this. It's not that it's inconvenient in the water, but it's very troublesome to put on and take off."

Liu Tan looked at the water bank, thought for a moment, and said, "Perhaps... it can be improved."

Lu Xuan asked in confusion, "How can we improve it?"

Liu Tan didn't say anything, just drew a picture and asked the people below to do it.

Lu Xuan took a look and was stunned for a moment: "Square? What is this?"

Liu Tan said seriously: "Swimming trunks!"

Although we don’t have the materials we have in later generations, fish skin can also be used.

This not only avoids the trouble of putting on and taking off the water jacket, but also avoids the embarrassment of everyone from the emperor to the ministers walking the bird in public.

Even if Liu Che didn't care, Liu Tan felt that the scene was probably a bit annoying.

It is also safer to ride on the slide wearing swimming trunks. Otherwise, you have to wear clothes, and it will be uncomfortable if the clothes get wet and stick to your body.

This thing is not considered an invention for Liu Tan, basically he just needs to give an order.

It has to be said that by having this done he indirectly saved the craftsmen who were making the water backrest. After all, making a complete water backrest takes a certain amount of time and requires accurate physical data.

The most important thing is that Liu Tan needs a lot of sets. In addition to reserving sets for the people brought by Liu Che, he also needs to get some spare ones in case of any accidents.

Swimming trunks are much more convenient and do not require too detailed data.

After Liu Tan gave the order, he looked at his schedule and found that there was nothing he needed to do recently. He decided to take a break from his busy schedule and spend two days with Lu Xuan. They hadn't seen each other for several months.

This time, Lu Xuan probably came to see him before going to war. In the future, unless the war is over, he probably won't have time to come.

After Liu Che came, the two of them must have had little time to spend alone together, so they could only take a break now.

As a result, he had only been relaxing with Lu Xuan for two days when Gongshu Yi came to visit him.

Gongshu Yi looked at Liu Tan eagerly and said, "Your Highness, the tree house has already been built, but there is a problem that has not been solved."

Liu Tan, using his sleeve to cover his hand, squeezed Lu Xuan's hand and asked sternly, "What's the problem?"

Gongshu Yi said, "Regarding the lighting issue, we can use candles or oil lamps inside the tree house, but if we use lanterns outside, what if there's a fire..."

Liu Tan was stunned for a moment before he said, "Don't worry about that. I'll have someone make some glass lamps."

He had overlooked this point. It was indeed a bit dangerous to light a fire in the woods. Although it was summer and humid, the Northern Territory was dry to begin with. In addition, there must be a lot of flammable materials around the tree house, so fire-fighting facilities must be well prepared.

Liu Tan put the issue of firefighting on the agenda, but most firefighting these days involves setting up water tanks. Once a fire is discovered, water is directly drawn from the nearby tank.

However, after Liu Tan learned more about it, he found that the fire-fighting methods of this era seemed to be relatively backward, and the fire-extinguisher had not yet appeared. If you think about it carefully, it probably appeared in the Ming and Qing Dynasties.

After taking a look at the schedule and doing some calculations, Liu Tan decided to have the craftsmen work overtime to make some laser tubes.

There are two types of fire guns: the Chazi fire gun and the Western fire gun. The Chazi fire gun is a local fire gun. The whole shape is more like a water gun, with a sleeve on the outside and a piston on the inside. The sleeve is placed into the water tank through the piston to absorb water, and then it is used to extinguish the fire.

The fork gun does not absorb much water and has a limited range. Its only advantage is probably its portability.

The Western laser can be considered an evolved version of the Chazi laser, and is semi-mechanical.

The Western pump consists of a water tank, two suction cylinders, two discharge cylinders, a pressure beam and a main discharge pipe. The suction cylinder still needs a piston, while the discharge cylinder can rotate flexibly and adapt to any direction.

When in use, lift the pressure beam and press it down. The pressure beam controls the piston in the water suction cylinder. When lifted, the piston moves back and the water suction cylinder sucks in water. When pressed down, the piston is pushed back and the water is pushed into the water outlet cylinder and sprayed out.

This mechanism is neither difficult nor simple. The most important thing is the production of the piston.

If it were in later times, it goes without saying that the piston would definitely be made of rubber to achieve the purpose of sealing, but in this situation, Liu Tan had to call Gongshu Can over to ask him what he thought.

Gongshu Can looked at it and laughed, "Don't worry, Your Highness. Use beef tendon."

"Ah?" Liu Tan was a little surprised: "Beef tendon?"

Gongshu Can said seriously, "That's right. Our Gongshu family has also developed this piston. We carve it into a round shape out of wood, dig out two grooves in the head, and then fill it with beef tendon to create a seal."

Liu Tan thought about it for a moment and thought there was no problem. He handed him the blueprint and said, "These two are the new laser tubes I've researched. Let's see if we can make them."

Gongshu Can's face was full of questions: "Excitation tube? What is it... used for?"

"Put out the fire."

Liu Tan felt that if the laser tube could be made, it would be quite useful. The Weiyang Palace was also made entirely of wood, or in other words, all the palaces today were made entirely of wood. If a fire broke out, it would definitely be a disaster. Think about how sad Liu Che was when the Bailiang Terrace was burned down before.

In fact, the fire at Bailiangtai seemed to be just an accident, and the fire was not big at the beginning. However, due to the low efficiency of fire extinguishing, Bailiangtai was directly burned down.

The emperor's team specially used for firefighting must be the most efficient. If they can't come to the rescue, it can only be attributed to the backwardness of their tools.

Now that we have the fire torch, we can’t say that it can 100% put out the fire, but at least we can rescue the people.

However, Gongshu Can felt that he really could not keep up with the thinking of His Royal Highness the King of the Northern Territory. How did he jump from the elevator to the fire extinguishing device?

But since his boss gave the order, he had to do it.

This problem was not a problem for Liu Tan. After finishing the blueprint, he began to think seriously about another thing - the glass lamp.

When I gave Lu Xuan a gift before, the underwater glass lamps were all made of glass plates spliced ​​together and coated with waterproof material in the middle, but this was too inefficient and the shapes that could be made were also limited.

Feeling that glass had now developed to a certain level, he thought he could move the craftsmen to the next stage - glassblowing.