Soon, the old craftsman Niu Dafu took Chen Jin, the governor of Liangguang, and his party, surrounded by the guards of the brigade, to the southwest corner of Luorong County.

Niu Dafu pointed to a section of the city wall and said:

"My lord, this is it! There was a flash flood that year, rushing from the west. Among the thieves, there were masters, and they proposed to use large ships, and put a number of iron tools in the bow. Then, thousands of people pushed large boats, along the torrent, and hit the city wall, causing the city wall to be knocked open a gap......"

Chen Jin stroked his beard and said:

"This is a brilliant way to break the city!"

Niu Dafu nodded and said:

"It's wonderful, but it's also a good idea. At that time, the flash flood was rushing from the west, and the current was very fast. If the water flow is gentle, the impact force is not so great, and it may not be able to break through the city wall. However, because of Hu Zhuji's corrupt behavior, this section of the city wall is not reliable. It is not made of glutinous rice juice and brown sugar, etc., and with more than 30 years of wind and rain, it is definitely not very reliable. Therefore, the old man thought that he could try to hit it with artillery, or he could open the gap. ”

"That's great!"

So, according to the instructions of the old man Niu, the Ming army mobilized 20 earthen cannons to bombard that section of the city wall. Sure enough, I heard the difference......

If you bombard a general city wall, the cannonball will make a crisp sound when it hits the city wall. However, when the cannonballs hit this section of the wall, there was a muffled sound. This muffled sound is somewhat similar to the sound of a weakened drum...... Obviously, the walls are indeed hollow......

As a result, the artillery bombardment of the Ming army became even more vigorous. After all, there was no shortage of gunpowder in the Ming Dynasty. Of the ingredients for saltpeter, charcoal, and sulfur, only sulfur is slightly insufficient. After all, the Ming Dynasty does not produce natural sulfur, and it is often the Fangshi who get sulfur from pyrite. Therefore, very different from the situation in Europe, the Ming Dynasty was the most expensive for sulfur, while saltpeter and charcoal were cheaper......

Of course, the so-called high price of sulfur is also relative. Compared with Europe, sulfur here is still cheap, only a few dozen cents per catty. Therefore, the cost of Daming gunpowder is low, and there is no need to be stingy with it. After all, now ordinary civilians celebrate the festival and set off firecrackers made of gunpowder.

But booming, everyone was a little embarrassed to find that those Ming Dynasty-produced earthen cannons seemed to be not powerful enough......

Why? First of all, the caliber of those earthen cannons is relatively small, similar to the Francose cannon, or even a little smaller. In addition, the body tube is shorter...... In this way, the speed of the cannon is slower, and the impact force is smaller......

What's more, the artillery of the Ming Dynasty at this time was especially made of stone bullets. After all, there is some luxury in using iron bullets. Moreover, these earthen cannons are usually used to bombard enemy battle formations in front of the formation, and are rarely used to bombard the city wall.

Two days later, Old Man Niu took Chen Jin to observe the results and found that it was not ideal. The walls were bombarded with stone shells, and they seemed to loosen somewhat, but they were just a little bit worse......

"It would be nice if it was replaced with an iron bullet!" Niu Dafu shook his head and said.

"It's difficult, iron ball cannonballs, not nothing. However, it is difficult to make the right shells. After all, if it is not suitable for artillery, iron balls are difficult to polish, while stone bullets are easy to polish. A veteran gunner said.

At this time, Chen Jin's staff Master Zhou suddenly said:

"Dong Weng, have you forgotten the ten Franco cannons sent by the ghosts?"

Chen Jin slapped his head and said:

"yes, I almost forgot about them!" Chen Jin hurriedly ordered the governor's personal battalion to drag all 10 Furlong cannons to the front of the battle......

Then, these 10 Furlong cannons, taking the place of the short-barreled Daming earth cannons, began to bombard the city walls......

The 10 Furlong cannons were all equipped with iron bullets, a total of 500 rounds. And the rate of fire of the Furlong cannon was very fast, and it ran out of shells in ten minutes...... Although the city wall was smashed to pieces by 500 iron balls, there were no shells......

So, the Ming army let the sword and shield soldiers hold the shield and go to the bottom of the city wall to recover the iron ball cannonball......

However, there was generally a moat around the walls of the Ming Dynasty, and most of the 500 iron ball shells fell into the moat. In the end, the Ming saber and shield soldiers only recovered more than 90 shells after paying some price - these were smashed on the city wall and bounced back to the ground...... If you want to recover more, you have to dive into the moat to fish. But the rebels at the head of the city are not blind, and if you dare to go down to the river to fish, they will surely stone you to death, or shoot you with arrows...... So, there is only so much that can be recycled......

"It's not enough to fight!" Chen Jin was suddenly a little depressed.

At this time, Li Sanshui, a hundred households mobilized from the Guangzhou avant-garde to help train artillerymen, suddenly came out of the crowd and said:

"My lord, we can cast more cannonballs!"

"Cast cannonballs? How to mint? "After all, Chen Jin is a civil official, so he doesn't understand this.

Li Sanshui waved his hand, let his subordinates take a sand box up, pointed to the sand box and said:

"We can turn over the sand to cast iron bullets, very fast!"

After speaking, Li Sanshui briefly explained the process of casting shells using green sand and sand. This method was actually introduced to him by Kong Tai. Even this sand box was sent by Kong Tai.

Niu Dafu asked questions at this time:

"Master Li, Lao Yu is a craftsman, although he specializes in civil engineering, he also has a little understanding of casting. If you cast an iron bullet according to your method, the iron bullet must have potholes on it! After all, when the green sand is poured into the molten iron, the water vapor must be rising, so that there are many gaps in the shells! Such a cannonball, it's not real! ”

Li Sanshui remembered what Kong Tai said at the beginning, shook his head, and said:

"Uncle Niu, this is a bad statement. This kind of casting law enforcement will indeed make the shells empty again. But so what? Aren't iron bullets with gaps and iron bullets without gaps both used to smash people and walls? As long as the size is right, the artillery can be used, so why care if there are gaps? ”

Niu Dafu thought about it, it was really ......

The craftsmen of the Ming Dynasty do not know how to turn sand casting, but the use of green sand casting, the iron has many gaps, and it is often not reliable. Therefore, regardless of whether it is a cannon or an iron ball cannonball, the clay mold method is later used.

However, the biggest disadvantage of the mud mold method is that the drying of the mud mold takes at least two or three months. Moreover, after using it once, the clay mold is wasted. Therefore, casting iron cannons and iron ball cannonballs is so troublesome. In addition, iron is more expensive, so most of the Daming artillery uses stone bullets. After all, stones are everywhere.

In fact, the craftsmen of the Ming Dynasty also fell into a misunderstanding. Because the artillery resists a certain amount of chamber pressure, it naturally cannot have air holes, otherwise it will explode. However, the cannonball is not so precious, anyway, it is pushed out by gunpowder gas to smash people, and it does not need to be so precise.

After all, the shell wants the kinetic impact of its mass, not its durability. As long as the quality is about the same, a flawless iron ball and an iron ball of the same mass full of gaps will actually have the same effect.

In addition, if you cast it with green sand, it is very fast. As long as the molten iron is poured through the injector into the hollow part of the iron ball pressed out in the two halves of the sand box, the cannonball can be formed in no time. Although the water vapor will make a lot of honeycombs on the iron ball because the wet sand is heated and transpired, so what? It's just an iron ball that smashes people and walls, why do you want to be so precise?

After figuring out this section, Chen Jin hurriedly ordered to collect iron materials everywhere, and then, open the furnace to melt the iron. At the same time, after making dozens of sand boxes, and then getting some river sand in the river, I began to cast inferior iron ball shells in batches by the green sand method......