Qin Chuan took Song Zhiting, Wang Jizong and others, standing on the Shitanling and looking at the end of the road in the distance, chatting about the development of Lou Fu.

The howling north wind blew on the shiny black mink coat on his body, and the soft fluff blew in waves, which looked very beautiful.

In the distance, a team, a hundred horses, and a carriage, slowly approached Shitanling.

When he got closer, Qin Chuan took the initiative to greet him, opened the curtain of the carriage with a smile, and arched his hand inside: "Lord Chen, it's been hard all the way." ”

Chen Zhan in the carriage raised his head with difficulty and asked suspiciously, "Are you ......?"

"Contemptible Qin Chuan, the chief steward of Mengjiazhuang in Lou Fu Town."

"It turned out to be the Great Steward of Qin."

Chen Zhan reluctantly sat up, returned the salute, and said, "Chen is a sinner, and he deserves to be called an adult." ”

"Lord Chen is too modest, in Qin's opinion, although Sun Futai died unjustly, he is still the Lord Sun who is loyal to the country, and Lord Chen is still the Lord who is brave and loyal."

The movement of Chen Zhan's hand froze, and he opened his mouth but couldn't say anything.

"Lord Chen, Qin has already sent someone to Anqing Mansion to look for your family, if they are willing, Qin will send someone to escort them to reunite with you."

Chen Zhan trembled slightly, excited, and solemnly saluted Qin Chuan.

"Lord Chen doesn't have to be polite, let's rest first, Lou Fu Mengjiazhuang is right in front of you, and you will be there immediately."

Qin Chuan lowered the curtain, walked to the side, and greeted the two middle-aged men who were riding on horses with haggard faces.

Zhao Mancai jumped off the horse very cleverly, ran to Qin Chuan with his waist bent, and said with a smile: "Little Zhao Mancai, I have seen the Great Steward Qin, thank you for the rescue of the Grand Steward Qin, and the small one will do his best to repay." ”

As soon as he heard this tone, Qin Chuan knew that this was the head craftsman who survived because he was lazy and did not go to work.

The most amazing thing is that this guy has been working in Wang Gong's factory for more than 20 years, and there are times when he is lazy and does not go to work, but the gunpowder handled by him has not made a single mistake.

That's why this guy can become a craftsman, but he can't go any further.

In Wang Jizong's words, this is a strange man from the ten continents, and a strange person.

After saying hello to this strange person and chatting a few words, Qin Chuan took the group of people to return to Loufu.

Luo Wentian didn't come back, Qin Chuan allocated fifty Guan Dijun, who was more clever and skilled, to him, and asked him to go to the Shuntianfu area to find pig iron buyers, and by the way, recruit more craftsmen, as many as he wanted.

Lao Huang and Lynx didn't come back, they only sent people to the area of Lan County, and after the hundred people sent by Qin Chuan responded, these two people took the Fifty Guan Imperial Army to dress up in disguise and disappeared quietly.

This trip they made a great contribution, not only brought back Chen Zhan, Zhao Mancai and two ambassadors of the Ordnance Bureau, but also brought back more than 20 craftsmen, in addition to blacksmiths, leathermen, carpenters, bricklayers, and a furnace master who had stayed in the Fujian official iron field, and two armor craftsmen from the Nanjing Military Bureau.

For Qin Chuan, these two armor craftsmen are baby bumps.

The War Bureau is mainly for the emperor's guards, brocade guards and generals at all levels to make equipment, the weapons and armor that come out of it are naturally much better than the Weapons Bureau and the local guards, and it has always been the standard for the supervision of the guards.

With these two armor craftsmen, it is not a dream to greatly increase the armor rate.

Qin Chuan has already moved most of the villagers out of Mengjiazhuang and lived in Loufan Town, where they dug out the ground and lived temporarily if there were not enough houses.

The few courtyards vacated by Mengjiazhuang are being renovated, and a small cannon foundry and a gun factory will soon be built, and the original blacksmith shop will also be expanded to make cold weapons such as knives, guns, armor, etc.

As for the gunpowder plant...... Qin Chuan was afraid that Mengjiazhuang would be blown up by Zhao Mancai, so it was built at the foot of a mountain three miles away from Mengjiazhuang and Loufan Town.

The only problem in making gunpowder is saltpeter, the imperial court has a special nitrate field, and there are only a very few nitrate people who specialize in making nitrate and selling it to medicine shops, and the output is very low, far from satisfying Qin Chuan's appetite.

The place where a large amount of nitrate is produced is Yarkand.

There is a large saltpeter mine in Xiaocaohu in Turpan, and I don't know if the people of Yarkand know how to dig to make nitrate.

Now, Qin Chuan has to let people go around to buy saltpeter, and at the same time, he has to let the villagers gather in a few places to urinate, and he has to make a little nitrate first to use it first.

In addition, Qin Chuan planned to let Zhao Mancai wander around to see where there was a saltpeter mine nearby, no matter how small the reserves were, it would be meat.

……

Chen Zhan ate some meat porridge and rested for more than an hour before recovering a little more.

There were bursts of shouting and shouting in the distance outside the house, and Chen Zhan couldn't help but get up and go out and walk in the direction of the shouting.

When I entered a courtyard, I saw that dozens of sturdy men were busy erecting two tripod wooden frames, and the Qin Grand Steward of Mengjiazhuang was directing on the side.

Chen Zhan walked in, and after only a cursory scan, he knew what kind of place it was.

Artillery factory.

"Lord Chen, this place is a little smaller, let's use it for the time being, and when the time comes, we will build a large factory outside that can cast more than twenty cannons at the same time."

Seeing him enter the door, Qin Chuan turned around and said with a smile.

Chen Zhan didn't respond, but walked straight to Qin Chuan's side and asked in a low voice, "Chief Steward Qin, Chen wants to know, what do you want?" ”

"For the sake of the common people in the world, the people of Li." Qin Chuan had expected him to ask this, so he smiled and responded.

Chen Zhan didn't respond, only lowered his eyes and pondered silently.

After a long time, he sighed inexplicably, and then remained silent.

Qin Chuan smiled again and asked, "When Lord Chen followed Lord Sun before, what kind of cannon building method did he use?" ”

"Iron-hearted copper method." Chen Zhan did not hide it.

"Well, copper and iron are composite, strong inside and tough outside, and the gun body is much stronger than the iron casting method, which is a good method."

Chen Zhan was a little surprised: "Grand Steward Qin also made cannons?" ”

"I just know a little bit about it."

Qin Chuan pretended to be modest and shook his head.

In fact, of course, he has never made a cannon, but he has been in various forums in his previous life, and he knows that there is a method of making cannons called Rodman's internal mold water cooling technology, and there is also a method called Gong Zhenlin's iron mold cannon making method.

He didn't know exactly how to get it, but he knew the principle and the general method.

That's enough.

After only being humble for a moment, Qin Chuan continued: "Lord Chen should know that the weapon will become extremely hard after quenching. ”

Chen Zhan nodded: "Naturally, I know, but all weapons must go through a quenching process." ”

"That'...... Can we also make a cannon through a process like quenching to make the inner wall of the barrel extremely hard? ”

Chen Zhan was stunned for a moment, then shook his head and smiled: "Qin Daguan, this method is absolutely unworkable, pouring water when the cannon barrel is red will cause the cannon barrel to break, let alone quenching?" This method will only reduce the cannon to scrap metal. ”

"I know that." Qin Chuan smiled.

In fact, quenching and internal mold water cooling are completely different things, the former is to change the structure of metal elements, and the latter is to use thermal expansion and cold contraction to make the inner wall of the barrel harder and firmer.

He just couldn't find any other way to describe it, so he had to quote quenching.

Seeing that Chen Zhan was puzzled, he smiled again and said, "Since it is not feasible to pour water in a hurry, can we lead a water pipe into the barrel to slowly fill it with water, or blow air into it, not only to avoid the barrel from breaking, but also to cool down the barrel in a slow way and become stronger?" ”

Chen Zhan frowned, thought for a moment, and then shook his head: "There is an inner mold in the barrel, how can water be diverted into it?" ”

"It's not difficult, just cast a hollow iron mold, introduce the water pipe into the inside of the iron mold, and when the iron mold slowly cools down, the inner wall of the gun barrel will naturally cool down slowly."

"The so-called thermal expansion and contraction, as long as the inner wall and the outer wall are cooled at the same time, or even faster than the outer wall, the barrel will naturally be extremely strong, the service life can be increased several times, and the yield will inevitably be much higher, and the cost and time consumption are naturally much lower than the iron core copper body method."

After hearing his words, Chen Zhan didn't rush to respond, only frowned and thought hard.

Qin Chuan was not in a hurry, he just waited quietly by the side.

The rejection rate of cannons in this era is frighteningly high, reaching seventy or eighty percent, even if Sun Yuanhua invented the iron-core copper body method, and then used the lost wax method, the rejection rate is still more than fifty percent.

The main reason is the cooling rate.

After the cannon of this era is cast, it is slowly cooled from the outside to the inside, and in the case of thermal expansion and cold contraction, the difference in cooling speed can easily cause cracks in the barrel.

Even if there were no cracks, the outer wall of the barrel would be harder, while the inner wall would become loose and soft, not strong enough, and easily damaged by the impact of a gunpowder explosion, and scrapped after a hundred and ten rounds.

As long as the inside and outside of the barrel are cooled at the same time, or within a controllable range, the inner wall cools slightly faster than the outside, and the cannon is rarely cracked, and the service life can be five to eight times higher.

And Gong Zhenlin's iron mold cannon method...... This is very easy to understand, now the cannon is made with clay molds or wax molds, Gong Zhenlin directly made an iron mold, which can reuse the mold, and the casting speed is much faster.

The disadvantage of this method is that the barrel will turn into white iron.

For this problem, Qin Chuan has already thought of a way to solve it, annealing.

Qin Chuan also thought about the problem that water cooling can easily lead to the bursting of the barrel, and he can replace the water cooling with air blast, so that the cooling speed will slow down, which can greatly reduce the risk of the barrel bursting.

……

Probably thinking that what Qin Chuan said was feasible, Chen Zhan's face gradually showed excitement, and he suddenly bowed solemnly to Qin Chuan, and said, "Thank you Qin Daste for your advice."

"Lord Chen is polite." Qin Chuan smiled.

"The chief steward, he is no longer an adult in the next place, and please change the title of the chief steward, call him by his name, or call the table word, and he will not be able to do it under the table."

"This ...... Good, good. ”

"Steward, when can we start casting cannons?"

"Hmm...... It starts tomorrow. ”