Linley swiftly pulled out a wine flask, took a gulp, and immediately felt his fighting spirit rekindle. Although the Holiness had achieved victory in another dimension without gods, it didn't mean it would be so easy to win here.
He handed a grape leaf to Dave and instructed, "Find a suitable wooden board because I need to take it back to the cave."
"What is this?" Dave asked, puzzled.
"This is a one-way valve. If we install it in the cave, it will give us plenty of fresh water," Linley explained.
Dave was a bit worried, "Really? Won't it cause the fresh water to leak?"
Linley reassured him, "If there is a leak, we'll just refill it with sand."
Dave searched through the pile of wooden boards for a while and finally found a suitable one. He then took out an axe and saw to process it. At that time, metal tools were very expensive, and nails were even more costly, so much so that even in shipbuilding, they had to be used sparingly.
Pandora's design required many metal tools, including nails, hinges, wires, and rims, all of which were very precious. Fortunately, there were ready-made materials on the ship that could be dismantled and used; otherwise, starting from scratch would have taken a lot of time and effort. Even with raw materials, tools, and a blacksmith, making these parts would take several days and fall behind schedule.
Seeing this, Linley thought about the mortise and tenon joints used by ancient Chinese carpenters. Modern furniture rarely uses mortise and tenon joints because it's designed to last only a few years, often breaking within a short time. Ancient furniture, however, was built to be passed down through generations.
The Greeks didn't know how to make mortise and tenon joints, and nails were expensive, so people were reluctant to use them, causing wooden products to break quickly. Unfortunately, Linley himself didn't know how to make mortise and tenon joints; otherwise, he could have taught them.
"It's done." Dave and a few others worked all night and finally completed the one-way valve.
The whole device looked like a box, with a top and bottom that could be fastened or opened. When both the top and bottom were fastened, it was a sealed box, isolating fresh water from salt water.
If the latch was opened, it became a one-way passage, allowing water to flow from the top to the bottom but preventing it from flowing back up, as the metal latch would block it. The device looked good, but its actual effectiveness was yet to be seen.
"Of course not!" Pandora expressed dissatisfaction upon seeing the one-way valve. "Didn't I say it should be made of wood? Metal will rust in water and will break soon. Wood can last for years, but metal will only last two or three months."
Linley said helplessly, "But where can we get so many wooden parts in such a short time? Let's make do with this for now."
Pandora, however, was not in a hurry. "It's still raining, so there's no rush. Let's make another one and try."
Linley urgently said, "Let's first see if this one works. If not, we'll make a new one. We shouldn't expect to get things perfect on the first try; we should improve as we go, which is called iteration."
Pandora was confused, "But won't iteration waste a lot of resources? If we could do it in one go, iteration would mean doing it at least twice, wasting resources each time. We don't have anything right now."
Linley couldn't think of an excuse for a moment and had to say, "It won't be wasted. Wood can be recycled, and if metal rusts... we won't lack metal in the future. Anyway, we have the Thunder, and there's plenty of metal on it. Let's get to work and not waste the rainwater."
Linley and Pandora dived underwater and started digging through the sand with shovels. They dug several meters deep but still hadn't reached the bottom when suddenly, a surge of saltwater came up from below. Fortunately, the heavy rain quickly pushed the saltwater back down. They kept digging and soon uncovered a rocky cavern, filled with saltwater that tasted just like seawater. It was clearly seawater.
However, the inside of the cavern was completely dark. Linley tried to install a one-way valve, but it was too large for the small opening, making it impossible to fit. This was quite a predicament; if the valve had been too small, they could have blocked part of the opening, but with it being too large, they were stuck. Even if they forced it in, the shape mismatch would still cause leaks.
This was clearly a mistake. They should have measured the shape of the opening first and then made a matching valve, or worked underwater to adjust the valve to fit. In fact, the simplest solution would have been to bring down a large stone to block the cavern, separating the saltwater from the freshwater and eliminating the need for a complex one-way valve. However, it was unclear if using a large stone would be considered completing the task.
A large stone was obviously not as convenient as a one-way valve, especially when it wasn't raining. If the water in the pond was low and they needed to move the stone, the saltwater would rush in once it was moved, making the pond water undrinkable.
"This valve is completely useless. What should we do?" Linley asked in confusion.
"It can be used. I designed it perfectly," Pandora replied confidently.
Perfect? How could it be perfect if it can't be installed? Linley was even more puzzled.
Pandora chanted a spell towards the cavern, and its shape slowly began to change, eventually fitting the valve perfectly, although there was still a slight gap. Pandora placed the valve into the opening and chanted another spell, causing the cavern to tighten slightly and securely hold the valve in place.
So, magic could be used!
Linley tried shaking the one-way valve; it was very stable, as if it were part of the cavern. No wonder Pandora didn't understand the concept of iteration; using magic for a one-time perfect fit was naturally best, but it would be difficult to replace in the future. Apart from Pandora, no one else could accomplish this.
"See, isn't this great?" Pandora said with satisfaction.
"It is indeed great," Linley nodded in agreement.
Now, the freshwater and seawater were separated, with freshwater above and seawater below, not mixing at all. Additionally, by opening the valve, they could enter the cavern, using it as a secret passage.
"Let's see where it leads," Pandora suggested.
"Alright," Linley agreed, filled with curiosity.
If enemies attacked in the future and the island couldn't be defended, they could retreat through this secret passage. Or if they were surrounded, they could use the passage to launch a surprise attack on the enemy's rear, just like they did at the Temple of Dionysus in Athens.
The two entered the sea through the valve, surrounded by darkness, unable to see anything.
"Where are my tears?" Pandora asked.