The source of the green smoke was a round earth pillar, about 1.3 meters high, 1.2 meters in inner diameter, and 1.6 meters in outer diameter.

This hollow earth pillar is covered with two large ceramic panels, each covering half of the pillar.

Broken pottery pieces are placed under the pottery plate, so that there is a distance of about two centimeters between the pottery plate and the earthen column.

The green smoke and some flames came out from the edge of the propped-up ceramic plate and the gap between the two ceramic plates.

This is certainly not a beacon tower that burns smoke to give warnings, but a kiln built under the guidance of Han Cheng by Heiwa, a master potter of the Qingque tribe, after many failures.

The earthen kiln was not originally built here, but about a hundred meters away from here, closer to the river, where it was convenient to get water and mud.

However, after a heavy rain last year and the rising river water, half of the earthen kiln collapsed and could no longer be used.

Having learned from that lesson, Heiwa spent nearly ten days rebuilding this earthen kiln, which was one size larger than the previous one, about a hundred meters away from the river bank.

This place is far away from the small river and the terrain is high. During the several heavy rains last year, the flooding of the small river did not reach here. Building the earth kiln here is indeed a good choice.

After several experiments and with the guidance of the Son of God, Heiwa managed to figure out some tricks in building earthen kilns.

The first thing is to choose a place where the earth kiln will be built and dig a pit about 90 cm deep, 1 meter long and 90 cm wide.

Then, in the middle of the pit, a wall about half a meter high was built vertically using the previously made adobe mixed with the mixed mud. Then, on top of the wall, three thin and hard wooden sticks were placed every ten centimeters, and the other ends of the wooden sticks were placed on the edges of the pit.

The previous kiln was small, so there was no need to add this wall. The wooden sticks could be directly placed on both sides of the pit. The kiln is bigger now, and if the wall in the middle is not added, the wooden sticks will not be able to bear the weight.

There is no need to worry about the sticks being burned by the flames because they are covered with a thick layer of clay.

Each group of three sticks are put together and then wrapped with mud. There is a reason for using three sticks. Firstly, it can increase the bearing capacity, and secondly, more mud can be wrapped on the outside. If there is only one stick, it is really not easy to wrap mud on it.

After these are done, we will continue to build the wall upwards.

After the wall in the pit is flush with the ground, continue to place the sticks wrapped in a thick layer of clay on it as in the previous step. The sticks should be placed more densely than the layer below, because this layer will be used to place the clay embryos that need to be fired, and it cannot be built without a solid foundation.

Once these are done, the bottom of the entire kiln is built, and all that remains is to mix the mud and start building the walls of the kiln.

Just like the rammed earth walls in the tribe, chopped hay and some salt were also added here. Based on the experience gained from the previous earthen kiln walls that were prone to cracking, Heiwa also added some sand in cans brought from downstream into the mud.

The banks of this small river are mostly mud, and only on the shallow side of the bend is there sand accumulation.

There is one thing that needs to be mentioned specifically, and that is the matter of adding salt inside the wall when it is built.

This move was really a waste of salt, and after some thought, Han Cheng changed his approach.

It’s not that we don’t add salt to the mud anymore, but we don’t add purified salt anymore.

The salt mines transported back from the salt mountain are simply crushed and added to the mud, which saves a lot of effort.

The mixed mud was piled up in circles. In order to ensure that the kiln was round, Heiwa used two wooden sticks for comparison. One stick was 1.2 meters long and the other was 1.6 meters long.

This method was taught by the Son of God before. At the beginning, the pottery made by hand was always not round enough. After the Son of God taught this method, the problem that had troubled Heiwa for a long time was immediately solved.

Later he used it to build the kiln wall.

For Heiwa, building a kiln wall actually has many similarities with building a pottery jar, which is not difficult for him who likes to deal with mud.

Because the kiln wall is made purely of mud, and the newly mixed mud is relatively soft, so every time it is piled up to a height of thirty centimeters, it is necessary to light a fire underneath to bake the kiln wall more solid before continuing to raise it higher.

The earthen kiln was emitting green smoke, and before you even get close to it, you can feel a wave of heat coming towards you.

About ten meters away from the earthen kiln, there are several large stones with relatively flat surfaces, and Heiwa, with muddy hands, is busy here.

He casually pinched some fine dry soil from the pottery jar below and sprinkled it evenly on the stone in front of him, and then placed a wooden frame about half a centimeter thick on it.

The wooden frame is made of a tree stick that is broken in the middle and has a certain degree of flexibility, and the joints are tied with ropes and straw.

The flat side of the broken wooden stick faces inward, and the curved side faces outward, to ensure that the edge of the pottery is smooth.

The wooden frame is not a standard rectangle, but an isosceles trapezoid with one end larger than the other. The gap between the upper and lower bases is one and a half centimeters, so that the tiles made in this way can be seamlessly connected.

It wasn't like this at the beginning, but a standard rectangle.

After overcoming the curvature problem of tiles with the help of the Son of God, Heiwa finally fired the first batch of tiles.

Heiwa was very happy when he saw the first batch of things called tiles by the Son of God, because the Son of God said that this thing could be used to build houses that were better than the deer pens, and in time everyone in the tribe could move out and live in the houses.

Although he didn't know why the Son of God wanted to move out of the cave, just by looking at the longing expression on his face when he said this, Heiwa knew that this house must be more comfortable to live in than the cave where they had lived for generations.

In addition to the reason of the house, he was happy for another reason, that is, he had completed the task assigned by the Son of God, and the Son of God looked at the tiles he had fired with a look of joy on his face.

This was undoubtedly the best compliment to his craftsmanship, and Heiwa was of course very happy.

However, his happiness did not last long, because after the Son of God put the two tiles together for a while, he suddenly put them down, smiled bitterly, and slapped his forehead.

This made him worry that his poor cooking had caused the Son of God's displeasure.

Heiwa's craftsmanship was naturally impeccable. Although it was his first time to fire tiles, he had the experience of firing a large number of pottery before, so the tiles he fired were very successful. They were almost the same as the small tiles Han Cheng had seen in later generations.

Of course, this ignores the disadvantage that the fired tiles are the same size at both ends.

The two ends of the tiles are the same size, which means that there will be a gap when the two tiles are stacked together. Using such tiles to lay the roof will easily cause leaks.

After a period of modification, the mold used to make tiles became what it is today.