After the completion of Qingyazhuang, Chen Xian asked some construction workers to help the agricultural company's people open up fields downstream of the Qingya Reservoir.

The foundation of the irrigation system of the Qingya Reservoir has been completed, and as long as this land is developed, it will be a good irrigation land.

Chen Xian estimated that at least more than 3,000 acres of land could be cultivated in this area downstream of the Qingya Reservoir, and if part of the fields in Dongzhuangzi were also included, the Qingya Reservoir could irrigate at least 5,000 or 6,000 acres of fields.

Chen Xian sent the remaining construction workers to Xinzhuangzi and began to build a dam upstream of the Beigou River to raise the water level, on the one hand, to increase the flow rate of water at the Xinzhuangzi Hydro Factory, and on the other hand, to build an irrigation system to turn the fields downstream of Xinzhuangzi into irrigated land.

After eight years of difficult spring in Taihe, everything seems to be fine, but Chen Xian has fallen into a new torment.

What made Chen Xian suffer was the "cannon" problem.

In fact, Chen Xian has been struggling with whether to make cannons since very early on.

It doesn't seem like a problem to worry about at all, doesn't it? Cannons are such a good thing, why not make them?

Napoleon described artillery as the king of the battlefield, and in Napoleon's time, artillery played an even greater role on the battlefield than flintlock pistols in the hands of soldiers.

The reason why Chen Xian hesitated to make cannons was because he knew that cannons were far more useful against infantry than cavalry.

However, Chen Xian's imaginary enemy in the future is a powerful army of pure cavalry.

In other words, if Chen Xian made a cannon and was learned by his enemies (this is very likely, the original cannon is not too complicated), then he is likely to shoot himself in the foot.

You must know that the infantry phalanx of the arquebus era was most afraid of artillery.

So Chen Xian has been struggling with whether to let the cannon appear in this world in advance.

Making cannons, for fear of learning from the Mongols, may change history and make the Southern Song Dynasty finish ahead of schedule.

Without making artillery, the difficulty of siege increases on the one hand, and what is even more worrying is that without artillery assistance, the combat effectiveness of the infantry phalanx is worrying.

If there are cannons, it will be easy for Chen Xian to take a small city like Dongzhuangzi.

After repeated consideration, Chen Xian finally decided to make it!

In the big picture, guns will eventually help civilization triumph over barbarism.

From the technical aspect, the simplest cannon has a very low technical content, even lower than a musket, since Chen Xian has already made a musket, then others can easily associate it with enlarging the gun to create a more powerful artillery.

At the same time, Chen Xian also believed that even if the technology of the cannon was learned by the Mongols, he was sure that his cannon would hit farther, more accurately, and more powerfully.

Although he has been entangled in his heart, Chen Xian has actually been consciously or unconsciously preparing for the casting of cannons.

For the past two years, Chen Xian has been hoarding copper and copper coins.

Because of the melting point and the nature of the solution, the casting of steel can only choose to use pig iron as raw materials, pig iron casting cannons have many disadvantages, first of all, they are too brittle, easy to blow up, and also because they are too brittle, too hard, they will not be deformed before the blow-up, almost without warning, which makes the cast iron cannon become a death-like existence, once it is blown up, it is bound to be a heavy casualty.

When casting a cannon, because of the shape of the barrel itself, the heat dissipation rate of the inside of the barrel is definitely less than that of the outside. When casting and cooling, the outside that cools first shrinks first, and the stress inside the barrel is eventually outward, and this outward stress is easy to cause some dark wounds on the inner wall of the barrel, which is one of the main culprits that cause the cast iron cannon to explode.

Generally speaking, more than half of the cast iron cannon will explode directly in the initial test firing, and even if it is not exploded, it does not mean that it is safe.

When the cannon is fired, the force of the internal chamber pressure on the barrel is also outward, which leads to the pressure of the chamber pressure and the stress of the barrel itself are in the same direction, under the action of these two resultant forces, the service life of the cast iron cannon is far inferior to that of the copper cannon.

The combination of a short life span and no warning before the bore turned a cast-iron cannon into an even more formidable artillery killer than the enemy.

And with a bronze cannon, these problems can be avoided.

First of all, copper has a melting point of only 1083°C, which is lower than pig iron.

Secondly, whether it is brass or bronze, it has good toughness, which makes the copper cannon produce some deformation before the explosion, and through these signs, the explosion of the copper cannon becomes predictable, which greatly improves the safety factor of the copper cannon.

In the process of casting the cannon with copper, although there is also the problem of inconsistent internal and external cooling speed, because copper has excellent toughness and ductility, most of the stress generated in this process will be digested by the material of the cannon body, that is, the copper cannon will directly deform and release most of the stress, while hard and brittle pig iron cannot do this.

This greatly improves the yield of cast copper cannons, and the service life is longer than that of pig iron cannons.

Therefore, to cast a cannon, it is best to use copper, at least before the invention of the inner mold water cooling method, the cast iron cannon is far inferior to the cast copper cannon.

The casting of cannons, as a lover of ancient wars, Chen Xian himself knows better, and there are even specific size parameters of the famous Napoleonic cannon in the database of the online author, and all kinds of technical information are very comprehensive, from the sand turning method to the iron fan casting method, and then to the Rodman casting cannon method, everything is available.

In the past two years, Chen Xian has used casting methods to make iron rolling mills, various gears and axles on water turbines, and has accumulated considerable experience and technical foundation in casting.

Therefore, the casting itself, for Chen Xian, is not much of a problem, the problem lies in the quality of the copper.

In this era, there are no copper coins that are not mixed with tin and lead, and the so-called high-quality copper coins are only mixed less, and Chen Xian wants to cast copper cannons, so he naturally goes for the best, otherwise he is irresponsible for the lives of his subordinates.

In order to forge the best cannon, the material is, of course, the most important thing.

In the information of the Internet writer, a copper alloy called guncopper was recorded, which belongs to a type of bronze, containing 88% copper, 10% tin, and 2% zinc. This should be the casting of copper cannons, the best alloy scheme, but unfortunately Chen Xian spent a lot of effort and did not find zinc in this era, maybe zinc has not been discovered in this era, or zinc in this era is not called zinc.

Without zinc, it is naturally impossible to configure gunmetal, but even if guncopper cannot be made, ordinary bronze with only copper-tin alloy must have a better proportion.

In order to obtain an alloy with an accurate ratio, it is natural to have a metal with high purity.

Therefore, before casting the cannon, it has become an indispensable step to refine the copper and tin in the hand.

In the information of the Internet writer, there are many materials on the pyrotechnic refining of copper, tin, and zinc.

The web writer also took into account the question of the purity of ancient metals.

To remove the high content of tin and lead in copper coins, you can use the principle that the melting points of tin and lead are lower than copper, and remove the mixed tin-lead impurities in copper coins by heating the raw materials above the melting point of tin and lead and below the melting point of copper.

To achieve this, Chen Xian designed a reverberatory furnace with an internal chute.