Ren Baqian sat on a chair in a daze. He happened to sit under the shade; however, the temperature of his surroundings remained scorching hot.

It should be late autumn in Dayao now, but the weather remained blazing hot.

The clink and clank of pickaxes striking metal came from the distant Mount Damo.

After they burned the mountain yesterday, hairline cracks appeared on the wall of the mountain. This made Gu Qiong and Tao Jiyuan overjoyed. They felt that they had found a solution to the mining problem at Mount Damo.

However, Ren Baqian wasn't as optimistic as they were. He reckoned that only the surface of the mountain was affected. The inside of the mountain certainly hadn't been affected.

Of course, this was because both parties had different expectations. Ren Baqian wanted enough metal to forge weapons for a 20000-man army.

The standard saber that Dayao soldiers used wasn't the 1.5 kg sword that ordinary people used. Every saber was approximately 10 kg. It needed roughly 10 kg of iron to forge.

Every day, the thousands of prisoners in Mount Damo could only mine 40 kg of iron. This amount was enough to only make four swords. At this rate, they could only make 3000 swords for the next two years. Furthermore, he only took into consideration the needs of the army so far. The amount of iron they could mine was still utterly insufficient.

One had to know that the army wasn't the only one that needed weapons, hunters living in the mountains needed hunting tools, and commoners needed ironware as well.

For Mount Liucui, even though Ren Baqian had not gone there yet, he had already inquired Tao Jiyuan about it when they were chatting. It was located deep within a mountain range and the mountain roads there were treacherous. Even though it was much easier to extract iron from that mine, it was extremely difficult to transport the iron ores out of that place.

What could a nation that had a population of forty million do when it could only produce roughly 4000 kg of iron every year?

"Sir, Sir, we have mined at least 200 kg of iron today! It's equivalent to the amount of iron we mined over the last five days!"

Ren Baqian did not know when he fell asleep. He was abruptly woken up by Gu Qiong's excited, loud voice.

"Oh? 200 kg?" Ren Baqian rubbed his eyes and replied. It would take one day to burn a part of the iron mountain and drench it with water and one more day to mine the iron. The mining process seemed to have sped up.

"Increase the amount of wood then. It would be best to recruit more manpower from the surrounding cities to transport wood here. Spread out and burn the mountain from different areas. You can burn and mine iron on the east and west faces of the mountain alternatively every day. This will increase the efficiency slightly," Ren Baqian stretched his back and said. He was thinking what the surroundings of this mountain would become in a few years' time. After all, if they really wanted to mine iron from this mountain by burning it, the amount of wood they needed every year would be tremendous. Furthermore, trees took up to ten years to grow and mature.

Moreover, as the number of trees in the surroundings decreased, they would need to transport wood here from distant places to maintain the current mining speed. This would require much more manpower. For now, Ren Baqian could only think of this solution. After he returned to Earth, he would do some research on the concave mirrors.

"Sir, you're right," Tao Jiyuan replied. Ren Baqian was able to increase the speed of the iron mining process within two days' time. If he did what Ren Baqian said, the speed would increase even more. Immediately, Tao Jiyuan felt a sense of adoration towards Ren Baqian. He continued, "But we have to ask Her Majesty for permission first."

"Let's go and take a look." Ren Baqian stood up and let Gu Qiong lead the way. They headed to the foot of Mount Damo to observe the situation. Like what Ren Baqian had expected, only the surface of the mountain was affected by the heat. The cracks were merely five centimeters deep.

"Overseer Tao, please send a message to Her Majesty to let her know of the situation here," Ren Baqian turned around and told Tao Jiyuan.

During dinner time, Tao Jiyuan's and Gu Qiong's faces were still filled with excitement. Ren Baqian did not want to shatter their optimism. He merely said, "Tomorrow, I'm going to have a good rest. Don't disturb me even if there's something extremely important. There's no need to prepare my meals either."

"Yes, Sir Ren."

After bidding Tao Jiyuan and Gu Qiong farewell, Ren Baqian returned to the wooden house. He waited for everyone to fall asleep before returning to Earth.

　　...

It was only evening on Earth. Ren Baqian switched on his computer and searched for the article he'd seen last time. After typing the keywords into the search bar, he found it almost immediately. Furthermore, there was more than one article on it.

Someone had done this experiment seventy years ago. That person used a liquid mirror telescope to form a 50-kilowatt solar furnace that could melt a 1-centimeter-thick steel plate within thirty seconds.

20 years later, that man founded a laboratory and used ten thousand concave mirrors to produce 1000 kilowatt of solar power. It could increase the temperature of an object by 3500 degrees instantly.

The melting point of iron was 1538 degrees Celsius. Therefore, Ren Baqian did not need such a powerful solar furnace. He just needed a smaller version of it.

On a video he found online, a foreigner fitted 5800 fingernail-sized lenses to a satellite dish and used it to melt iron.

This information proved that Ren Baqian's idea was feasible.

He did not need such a huge laboratory as shown in the video. He merely needed a laboratory that was one-tenth the size of it. After all, his objective was to melt the wall of Mount Damo and he did not have a high demands on quality. As long as the solar furnace could focus on a certain part of the mountain and maintain an adequate temperature there, he would accept it.

That night, through Chen Qing, Ren Baqian managed to contact a physicist from a university in the city. The next day, he met that physicist and told him his request. He needed an adjustable solar furnace that was formed by concave mirrors. It must be able to melt metal three hundred to four hundred meters away.

The solar furnace also must be carriable by one person. Ren Baqian also wanted the blueprints for the solar furnace and all the concave mirrors.

To Ren Baqian, this task sounded very troublesome. To the physicist, however, this was an easy task. After all, Ren Baqian did not have high demands on quality. He could even give this task to his students to complete. Furthermore, Ren Baqian was paying him five hundred thousand yuan.

After settling this issue, Ren Baqian rested for two more days and went back to Dayao.

　　...

Mount Liucui was located among the sixty thousand mountains in the west of Dayao. However, it would take two days to reach the location of the mine from Dayao. Furthermore, the mountain road to the mine there was treacherous and arduous. Transporting iron ore out of that place was the biggest problem.

A few days after leaving Mount Damo, Ren Baqian travelled along this road.

When they just entered the mountainous region, the road condition was still alright. After all, this part of the road was frequently traversed by people.

However, after another day had pa.s.sed, the mountain road turned arduous and began to meander. On one side of the road, there was a cliff. On the other side, there was a mountain stream. The road was only one meter wide.

Humans could pa.s.s through it but definitely not animals.

Even humans couldn't walk very fast on it.

Every time Ren Baqian looked down the cliff, he would feel dizzy.

One had to know that the cliff was three hundred meters tall. If one fell off it, he or she would be smashed to smithereens.

Ren Baqian suddenly realized he had a huge weakness, that was, acrophobia.

He just had never realized it in the past.

Looking at Ren Baqian, Teng Ji felt very scared and worried. He followed closely behind Ren Baqian, preparing to hold on to him if he fainted and fell off the cliff.

If anything happened to Ren Baqian, he would not need to go back to Dayao anymore

After travelling for half a day, they finally reached a valley with cliffs on three of its sides. Ren Baqian could finally set his mind at ease. He felt that he had come back to life.

The valley wasn't very huge. Other than the one hundred or more guards, there were seven to eight hundred men mining.

The composition of iron in Mount Liucui was approximately forty percent. The difficulty of mining iron was reduced as well. However, the quality of the iron ores here wasn't really good. Furthermore, since it was very hard to transport supplies and iron ores in and out of this place, it was very hard to increase the iron output here.