In fact, Zheng Sen was not particularly worried about the possibility of the Spaniards attacking by land. Pen & Fun & Pavilion www.biquge.info Because the Spanish fleet was constrained by the lack of reliable supply points along the way, it would face great difficulties in replenishment. This also determines that the number of marines they can carry must be quite limited. Moreover, on the beaches where there were no ports, relying on small sampans, at most it was possible to transport only a few light infantry armed with muskets to land. How strong can such an army be in the face of a model army with fortifications and various artillery to support it? So for the fact that the three groups of batteries mentioned by Huang Cheng could not support each other in the land direction, Zheng Sen didn't care too much, just nodded. In fact, perfect fortifications never existed. Moreover, the fortifications, at least the Zheng family's fortifications, have always been offensive in nature.

In his "Treatise on Sea Power", Mahan of later generations had a wonderful discussion on the role of fortifications. Mahan believed that in naval warfare, the greatest significance of the existence of defensive batteries was to liberate the fleet, so that the fleet could be freed from the task of protecting the port and engaged in offensive operations. Zheng Sen believes that this view can be generalized to all defensive facilities. The greatest function of any defensive facility is to free up more troops from defense and use them for offensive operations. If there is no army behind the fortifications that can be used for offensive combat and can defeat the enemy in field battles at sea or on land, the significance of the fortifications is limited, no matter how perfect and strong they are. This is an important reason why my Ming Dynasty continues to fail in Liaodong. Starting from Sun Chengzong, the officials of my Ming Dynasty were full of fear of the "wild wave war" with Jianxuan, so they always fantasized about being able to rely on the "castle advancement", slowly build the castle, and repair it all the way to Shenyang. As a result, a lot of manpower and material resources were spent, and every time a castle was finally built, it was surrounded by Jianshen to help, and then, the castle was repaired in vain, and the materials in it were also sent to Jianshen.

However, the model army is different, the model army is not an army that lacks field combat capability like the Guanning army, and its organizational form has absorbed many influences from the later armies, and it can be said that it is ahead of the times in terms of weapons and organizational form. And this kind of leadership is not only the lead relative to our Ming army, or even the Jianxuan army, but also relative to Europe and the lead of Gu Erye. Therefore, in Zheng Sen's view, the threat of the Spaniards' landing operation was actually very limited.

"It's still too late, right?" Zheng Sen asked again.

"Major General, it's too late." Huang Cheng replied, "As long as the cement supply over there can be supplied, at most six months, these three forts can be built." ”

In later generations of construction technology, the production and use of cement can be a big killer. And there is no big obstacle in cement production in terms of technology, basically as long as you can burn lime, you can burn cement. As early as Roman times, the Romans used primitive pozzolanic cement, which was calcined from a mixture of volcanic ash and limestone. Of course, truly modern cement is much more complex and performs much better than that. However, Zheng Sen originally did not intend to replicate a completely modern level of cement, as long as it was stronger than ordinary lime slurry.

Zheng Sen vaguely remembers that the cement of later generations was often ground with limestone, clay, slag and other things, stirred evenly, and then sintered at high temperature, and then ground again. Now that the Zheng family has built a blast furnace in Qiongzhou to make iron, there are naturally a lot of by-products such as slag. As for limestone and clay, they are cheap things that can be found everywhere. So Zheng Sen asked people to try firing cement here.

Because he didn't know the proportions of the various ingredients in the cement, Zheng Sen had to let the workers try it themselves. In the end, a kind of cement was not bad, but because the production process needs to crush the rock, and Zheng Sen does not have an electric ball mill or anything, he can only use limited hydraulic power, so the production efficiency of cement has not been very high.

"I'm afraid the output of cement over there is not enough, right?" Zheng Sen asked. He also knew that the power problems encountered in cement production would inevitably limit its capacity.

"If you use this thing everywhere, it's not enough." Huang Cheng replied, "But we only use cement here on the side facing the sea, so it's still enough." The side of this fort facing the sea has almost been built, should the major general go and see it? ”

Zheng Sen nodded and said, "Let's go over and have a look." ”

The group walked to the side of the fighting room on the seaward side of the fort. This fort is the largest of the three forts of the main battery, the fort itself is built on a high shore that is more than two zhang high, and the pedestal is built with rammed earth more than three zhang high, the outer layer of the base is made of large stones, and the stones are used to avoid the collapse of the pedestal in the enemy's shelling, and the slope of the pedestal itself is not large. Zheng Sen looked down from above, and felt that if a person was empty-handed, plus a run-up, he should be able to rush directly. However, when it comes to battle, there will be guards on the battery, and under the attack of the guards' platoon guns and small cannons, it will be difficult to rush up.

The fighting room was built on this pedestal. The battery would be equipped with eight cannons for the sea, including four twenty-four-pounder guns and four twelve-pounder guns, so that on the seaward side, there would be eight fighting compartments. The fighting room is said to be a room, but it is not a complete house with four walls. The fighting compartment has only three walls, and the front wall facing the sea has a long firing port, from which you can look down on the entire bay, and you can also see the thickness of the frontal wall.

"The frontal parapet is three feet thick, made of wrought iron, cement and gravel, and is so strong that even the Navy's 18-pounder cannon cannons can't move a bit." Huang Cheng explained, "In this way, if the enemy gunboats at sea want to shoot at the battery, unless their shells can come in exactly through the firing port, they will not be able to damage the battery in the slightest." ”

"What about the dividing walls on the sides? Why is it so thick? Zheng Sen looked at the side partition walls and found that these walls were also about two feet thick, so he asked.

"Major General, the wall on this side is made of rammed earth with plywood, which only serves to isolate and prevent fire, so as not to ignite the gunpowder in one of the fighting compartments and affect the role of other cannons." Huang Cheng replied, "In addition, you have to prop up the top plate." The roof was thin, just a layer of logs, and then another layer of rainproof roof was made on top. As for the back, it is completely empty like this, first, it is easier to get in and out, and secondly, it is also brighter inside. Huang Cheng explained.

Zheng Sen walked to the firing port and touched the concrete of the front wall with his hand. The concrete was hard and a little chilly. He nodded with satisfaction and said, "Good job." If you do a good job here, we can deal with the Spaniards with confidence. ”

Zheng Sen and the others inspected the fort for a while, then got off the fort, got on the two four-wheeled carriages parked next to it, and then drove in the direction of the dock under the escort of a group of cavalry. Back at the docks, they had a lunch and then went to the ironworks.

From the dock to the ironworks there are two newly built tracks, which are made of iron-clad hardwood and have a layer of grease on them. Heavy-duty wagons loaded with coal were grouped together in groups of four, and then pulled by six horses, slowly moving along the tracks, and along the way, there were always a lot of cinders and small lumps of coal falling out of the vehicles. Whenever a horse-drawn carriage runs by, some local children rush to the tracks with wicker baskets, dustpans, and brooms, pick up these coals, sweep up the cinders, and take them home to be burned as firewood.

The carriage of Zheng Sen and the others did not go from this track, but followed a road paved with slag next to the track. After walking for about half an hour, I saw the black smoke billowing chimneys of the ironworks in the distance.

"In the future, with this chimney alone, the EPA will be able to shut down the factory. However, at that time, the world was afraid that it would be impossible to find such a backward factory. Looking at the chimney, Zheng Sen couldn't help but think like this.

As the carriage got closer to the factory, the air began to become cloudy, and it was filled with a pungent smell.

"Major General, mask." Liu De handed a mask to Zheng Sen, and it seemed that he had already prepared. Zheng Sen put on the mask, which contained a layer of activated charcoal burned from coconut shells, which was thin but said to be as effective as five layers of ordinary masks.

The carriage went a little further and then stopped. A few people got out of the car and looked up to see the big chimney in front of them.

"Where is it?" Zheng Sen asked.

"Major General, that's the chimney of the coke oven, and the coke oven is over there." One of the people who was with him replied.

Generally speaking, there will always be some sulfur-containing impurities in coal. If coal is used directly to make iron, these impurities will enter the molten iron, resulting in excessive sulfur content in the molten iron, and ultimately leading to a decrease in the performance of the smelted steel. Therefore, if the quality of steel is to be maintained, it is necessary to reduce the mixing of sulfur-containing impurities in the smelting. In ancient times, people did not understand this truth. However, this phenomenon was also discovered in experiments, so in ancient times, the usual method was to use charcoal instead of coal.

It's just that for large-scale steel smelting, the use of charcoal, or even any fuel other than coal, is impossible. Because charcoal needs to consume a lot of forest resources, and those forests in the world are simply not enough.

So the only way is to first pass the coal through the coking process and turn it into coke. The use of coke instead of coal directly to smelt iron was a big step in the history of metallurgy. But in fact, it is not particularly difficult to make coke. To obtain coke, it is only necessary to heat the suitable coking coal to about 1000 degrees Celsius under the condition of insulating the air, and these coking coals can produce a series of products such as coke, coke oven gas and coal tar through thermal decomposition and coking reactions. The vast majority of the sulphur in coal also turns into sulphur dioxide in the process. In later generations, this sulphur dioxide will be recovered to reduce pollution, but at this time, Zheng Sen did not have the technology to do so, so he had to discharge it directly, and this sulphur dioxide, which is one of the sources of pungent odors in the factory.