As soon as the West Courtyard lifted the alert, the students knew that the master was coming out. They quickly put down their work and ran over to greet him.

When Zhao Hao walked out of the room, he saw the six Yangs and one Zhao lined up neatly, bowed and shouted, "Master, you have worked hard."

Before they finished speaking, they began to spin the bamboo tubes in their hands. With a bang, colorful confetti flew out and covered Zhao Hao's head and body.

"Uh..." Zhao Hao was startled, and for a moment he felt like he was shooting a cheesy short video. He couldn't help but laugh and curse, "Whose idea was this?"

"Big Brother!" Everyone pointed at Wang Wuyang.

Wang Wuyang hurriedly smiled and said, "It's mainly because I haven't seen Master for a long time, so I wanted to do a simple ceremony to express my feelings."

As he said that, he quickly helped Zhao Hao take off the ribbons on his body.

"What is this?" Zhao Hao took the bamboo tube from him and looked at it. It looked very similar to the firecrackers used in weddings in later generations. But in his memory, those firecrackers were filled with compressed gas.

The disciples' eyes turned to Zhao Shizhen again.

"This is the spray gun I made. I hollowed out the joints of a bamboo tube, stuffed a paper roll on top, and filled the bottom with gunpowder. The bottom can rotate, and it is embedded with flint and fire steel. When it rotates, the gunpowder will be ignited." Zhao Shizhen laughed and said, "With a bang, the paper roll inside can be sprayed out."

"You're not afraid of blowing yourself up!" Zhao Hao patted his nephew on the back of his head, feeling happy. After all, this kid's thinking already had the shadow of a flintlock rifle...

He is indeed a natural arms expert.

Zhao Hao secretly praised and threw the bamboo tube to the eldest disciple. While walking towards the west courtyard, he asked the disciples if they had completed all the preparations before the exam.

The eldest brother flatteredly replied: "Master, according to your instructions, the disciples have focused on practicing the big questions this month. Each of them has done a hundred articles, which can be said to be very well prepared."

Zhao Hao's mouth twitched when he heard this. He thought to himself, your master only did one question, but he felt that he was well prepared.

He always felt a little sorry for his students because his caution prevented them from enjoying the joy of getting their guesses right 100%.

Therefore, before accompanying Mr. Zhao Er in seclusion, Zhao Hao had almost made it clear that the chief examiner of this exam would be Grand Secretary Li Chunfang.

Li Chunfang was a cautious official and extremely concerned about his reputation. Such a person would never use difficult and strange questions to show off his knowledge.

He is already the top scholar and the second-ranked university scholar. Is there any need for him to show off?

Therefore, it is reasonable to infer that the questions in today's imperial examination are big questions.

I hope that students can waste less time on the cut-and-paste questions, so that their already good results can be further improved...

~~

After the master and his disciples had a reunion dinner, Zhao Hao sent those who were about to take exams back to their rooms.

It's already this late, even if you do nothing and just sleep quietly, it's much better than chatting here.

The remaining three who did not take the exam sat on the kang and talked with the teacher.

"How's that thing going?" Zhao Hao asked without much hope.

He had heard a lot of explosions during this period. If the Newcomen machine was not very dangerous, he would have asked Gao Wu to stop the two people's experiment long ago.

Zhao Shizhen and Zhang Jian already felt guilty, and Zhao Hao's question made them wilted. The latter even burst into tears.

"Master, we failed to live up to your expectations. We failed..."

"Oh, is it the old explosion?" Zhao Hao took a sip of tea, looking like he knew a lot.

"Master guessed it right away." The two nodded in agreement.

"Let's go and take a look." Zhao Hao got up from the kang, and his disciples quickly helped him put on his warm boots.

When the master and his disciples arrived at the experimental room in the back yard, the first thing that caught Zhao Hao's eye was a Newcomen engine model made of bamboo and an iron kettle.

"Is this thing useful?" Zhao Hao asked with interest.

"This is useful." Zhao Shizhen responded, and quickly took a mooncake-sized homemade coal lotus root, lit it and put it in the bowl as fuel. He also said to Zhao Hao with admiration:

"My uncle's brilliant idea turned out to be correct!"

"This is science," Zhao Hao corrected.

"Yes, it's a fantastic idea based on science." Although Zhang Jian lacks confidence, he is very good at flattering others.

As he spoke, he filled the bamboo tube that served as a water tank with water. The water then flowed through a thin bamboo pipe, first spraying into the bamboo cylinder, and then into the iron kettle tightly connected to the cylinder.

Then the kettle was heated with coal. When it boiled, the steam rushed up to the thick bamboo that served as the cylinder. The increasing steam pushed up the piston of the cylinder, which in turn drove the lever at the other end down.

When the piston reached the top, Zhang Jian released water again. Cold water sprayed into the cylinder, and the steam inside cooled and condensed, falling back into the pot. The vacuum formed sucked the piston down again, and the lever at the other end naturally rose again.

Then the steam was reheated to push up the piston, and water was added to cool it, causing the piston to retract, and this cycle continued. In the steam, the lever was like a drilling machine in later times, constantly raising and nodding.

It can be seen that the two have thoroughly understood the simple principles of the Newcomen engine and perfectly restored the model, which makes them worthy of the title of geniuses.

After the model was successfully demonstrated, Zhao Hao turned his attention to the five or six cracked tin cans on the table.

"We asked the blacksmith to cast this," Zhao Shizhen said ashamedly. "We were going to make a scale model of the same material as the real automatic water pump. But the iron cans would burst after running for a while. One even exploded right after it was used."

Zhao Hao nodded and picked up an iron can. It had only been a few days and it was already rusty...

He explained to them, "This is a material problem. Because the cylinder is integrated with the boiler, it will expand synchronously with the boiler when heated. When cold water is injected, the inner layer of the cylinder will shrink rapidly. But the outer wall is still in an expanded state, and it will be subjected to a strong pulling force from the inner wall. However, the cylinder cast with cast iron is very hard and has very poor plasticity. If this is repeated dozens or hundreds of times, the uneven texture will crack."

"I heard that the government army's guns and cannons are prone to explode. Is this the reason?" Zhao Shouzheng really lived up to the title of weapons master and immediately thought of the idea.

"That's right. So to avoid barrel explosion, we have to use better materials or change the method of making the barrel." Zhao Hao smiled, put down the iron can and said, "It's not your fault. I was just hoping for the best. I thought maybe I could make do with it."

"It seems that we have to solve the material problem first." He sighed self-deprecatingly, gave up the idea of ​​killing and said, "Let's put this matter aside for now. You should study and lay a solid foundation first, and then we will slowly find a solution."

Seeing Zhao Hao about to leave the laboratory, Zhao Shizhen and Zhang Jian looked at each other. The former whispered: "Uncle, it's not all in vain. Sixth brother was inspired and built a water pumping device..."

"Oh?" Zhao Hao couldn't help but smile and asked, "Where is it?"

ps. The fourth update has been sent, 8600 votes plus more~~~