"Fixed?" David stood up, and several students stopped what they were doing and looked back at Xia Zuo.

"It's fixed, you can take a look!" Xia Zuo said with a smile as he straightened the small steam engine sideways.

David dropped the wrench in his hand, strode around a few students, walked to the wooden table, and after a brief inspection, he glanced at Xia Zuo with a strange look, walked to the side of the wall, pulled an arm-thick pipe, and turned around on the steam engine.

David glanced at Xia Zuo again and slowly unscrewed the valve.

Yikes!

The whole enters the engine through the pipe, and is discharged from a row of small holes at the top of the engine, the pressure in the engine gradually increases, the exhaust hole gradually closes itself, and the shaft of the steam engine begins to rotate slowly, and the speed is getting faster and faster.

It worked!

David didn't say anything very seriously, closed the valve, pulled out the tube, and turned to look at Xia Zuo.

"Xia Zuo, have you learned this before?" David was serious.

"Does self-study count?" Xia Zuo asked rhetorically, glancing at the steam engine on the table, and asked, "Teacher, are you okay?"

"Hmm!" David nodded and asked again, "These...... Didn't anyone teach you? What do you do at home? I mean, your father. ”

"I am a child of a nomad shepherd. Xia Zuo laughed.

"Okay, congratulations to Xia Zuo, I have officially promoted you to a second-year student in the Department of Mechanics, wait for me!" David smiled and walked to the door in the distance to the north.

A short time later, David walked out of the small room on the north side with a scroll of paper, walked up to Xia Zuo, and handed the scroll over.

"This is your first-class mechanic certificate. David said with a smile.

Mechanics are not a fighting profession, but they are an important profession in society, on a par with blacksmiths and tailors.

The certificates of the mechanical department are issued by vocational teachers, and with the certificate, even if you do not graduate from the college, you can find a good job in the dock repair factory, shipbuilding factory and other places after leaving the college.

It was a time of seafaring, trade was booming, but piracy was rampant, and the most used places for machinery were ship repair shops and shipyards, and first-class mechanics, although only a little more capable than an apprentice, could definitely find a job as soon as they left the academy.

It is said that David is a seventh-level mechanic, and he once participated in the design of the "Royal Queen", the flagship of the fleet when the queen traveled, and this level of mechanic is also a sought-after level talent even in the Steam Alliance.

"Have you read the second-grade books?" asked David with a smile.

"No!" Natsuzo shook his head.

Next, the whole afternoon, Xia Zuo spent the whole afternoon reading books, he had never touched the books of the second year of the mechanical department, in fact, if he wanted to read books, not only the college library, but also the bookstores outside, Xia Zuo had the ability not to sign up for the mechanical department, but also to buy those high-level mechanical books, although they were very expensive.

However, Xia Zuo's purpose is not here, the Royal College Library is the largest library in England, and the books about machinery in it, the top of the best, cannot be bought outside.

And Ray is going to be the best books.

What Xia Zuo needs to do now is to keep taking exams until he is promoted to fifth grade, and then he will have the right to borrow any book in the library's science and technology area.

At night, Xia Zuo hurried back to the wooden house with his books.

"Lei, what are you doing?" As soon as Xia Zuo entered the wooden house, he saw Lei's tall body sitting on a small stool in the corner, holding a slender steel pipe in his right hand, and his left hand had been turned into a cutting tool, tinkering with something on the steel pipe.

"It's nothing, it's boring, do something!" said Ray with a dead face.

"Come here, help me, I don't understand this paragraph......" Xia Zuo impatiently opened the book in his hand, beckoned to Lei, and walked to the side.

When he was in the Machinery Pavilion, David seemed to be tackling some technical problems, and he was frowning all afternoon, although Xia Zuo, who was reading the book, had a lot of questions in his heart, but he was not embarrassed to bother, so he came back to ask Lei.

As an artificial human, Lei is the pinnacle of human mechanical intelligence, and his ability to understand mechanical science and the amount of knowledge can no longer be measured by level, for Xia Zuo's question, Lei can already be answered in the simplest words, straight to the core of the problem.

Under Ray's teaching, Xia Zuo's progress has been very rapid, and the speed is difficult for ordinary people to understand.

Lei likes to answer Xia Zuo's questions very much, and never shows an impatient look, because this is not only helping Xia Zuo, but also helping himself.

Ten days later, early in the morning.

Xia Zuo, who slept very late last night, opened his eyes on time, rubbed his eyes, looked at the sky outside the window, and suddenly felt sleepy, he seemed to remember something.

Taking a bath, putting on clothes, and picking up a thick stack of books, Xia Zuo knocked on the ** board.

"I'm leaving, Ray!" Xia Zuo finished speaking, and walked out the door.

"Hmm!" thundered under the **, his eyes opened, and slowly closed.

The android doesn't need to sleep, but in Lei's situation at this time, he needs to rest, so whenever Xia Zuo sleeps, he will lie down ** to make his body enter a shallow dormant state, so that he can better absorb the free energy in the air.

Hurriedly leaving the wooden house, Xia Zuo came to the underground mechanical hall.

The lights are still dim, and it is still in that corner, after the large generator, several classmates have already arrived, and they have started to study under David's arrangement.

"Here, let's read a book!" David glanced up at Xia Zuo and said casually, lowering his head again, studying the hybrid engine in front of him.

This is an extremely difficult technical problem, Xia Zuo was studying it before he came, and it has been a month since he counted, and he has a headache every day.

"Teacher, I want to take the exam!" Xia Zuo looked a little excited, handed a thick stack of books to David, and said, "I've read all of this." ”

"Exam, don't you want to review again?" David looked at Xia Zuo in a daze.

"No need teacher, I want to take the exam!" Xia Zuo smiled, but said very solemnly.

He was very urgent, for mechanical science, Xia Zuo first came into contact with all because of Thunder, and began to understand it from the android aspect, but now, it was completely because of interest, Xia Zuo couldn't extricate himself.

"Go, the second table over there, put all the parts in different boxes according to the labels, and the rest of the parts, assemble a steam engine for me, and the little generator in the table is also broken, fix it. Be careful, don't make mistakes, any slightest mistake and the exam will fail. David said.

Compared with the last exam, this time it is much more complicated, and the difficulty has completely increased by several levels.

Xia Zuo walked to the table, looking at the hundreds of parts on the table, as well as the generator on the inside of the table and dozens of small bottles of all kinds, slightly dizzy.

After a little concentration, Xia Zuo moved.

"Hehe, there's a good show. Fourth-grader Alan pricked his eyes on the bridge of his nose and whispered to the Bell brothers beside him.

Hovis and Fernand, both sixteen years old, have the surname Bell, so they are called the Bell brothers.

"Uncle always gives people problems. Hovis whispered, glancing lightly at David.

That's right, he and Fernand are David's nephews, and they were able to become fourth-level mechanics at the age of sixteen, thanks in large part to their childhood, and their entire family is engaged in mechanics, and these two are the most talented mechanics the family has ever seen.

David had the idea of sending them to the Steam Alliance for further study, but it seemed difficult.

For a full twenty minutes, Xia Zuo was full of clanging sounds, and after a few minutes of silence, it lasted for a while before it completely stopped.

"Teacher. Xia Zuo turned around.

"You're all right?" David said, looking up.

"I didn't ...... There is no ......" Xia Zuo said slowly, slowly turning his head to look at the steam engine that was almost assembled in front of him, his brows furrowed deeply, "Teacher, the generator has been repaired, and the parts have been divided, but ...... This engine seems to be missing a part. ”

"What's missing?" David stood up.

"The rubber pad of the internal pressure valve, the round one......" Xia Zuo raised his hand and gestured, it was a very small thing.

Smack!

David clapped his hands twice, and a smile appeared on his face: "Very good, Xia Zuo." ”

After walking over and inspecting the generator and the box containing the parts, David looked at the half-assembled steam engine, took out the rubber mat Xia Zuo needed from his pocket, and said with a smile: "Load!"

In front of David, Xia Zuo quickly assembled the steam engine, put down the wrench, and looked at David again.

"Teacher, try?" Xia Zuo said.

"No need, I've seen it all!" David shook his head, paused and said with a smile: "Congratulations, Xia Zuo, I have officially promoted you to a third-year student in the Department of Mechanics." ”

took out the second-level mechanic certificate from the small room in the north and handed it to Xia Zuo, David patted Xia Zuo's shoulder heavily, and said with a smile in his seriousness: "Study hard, I am optimistic about you, if you can become a fifth-level mechanic in two years, I will find a way to send you and Hovis to the Steam Alliance for further study, work hard!"

In fact, David has always been surprised, surprised by Xia Zuo's learning speed, surprised by his curiosity, but these are not enough to make David make a commitment, he has not seen genius, he has two of them, what he values more is Xia Zuo's hard work.

In the morning, after finishing the exam, Xia Zuo left the mechanical hall and studied other courses, and it was not until three o'clock in the afternoon that he returned to the mechanical hall again.

Four o'clock in the afternoon, dusk.

The underground machine hall has no windows, and naturally there is no sunlight, and the electric lights are on, and it is still dim.

Xia Zuo, who had been reading for a long time, raised his head, rubbed his sore neck, and glanced at David on the side.

David was still working on hybrid engines there, in fact, hybrid engines had already been developed by the Steam Alliance and widely used throughout the world, and it was not a particularly difficult technique, but ...... The hybrid engines used today are all super-large, mainly used in ships.

And what David is now working on is a small model of hybrid engine, although the transformation from large to small, it sounds simple, but in fact it is the opposite, not an ordinary difficulty.

"Teacher, why don't you add three air return pipes to it? Then remove the middle spacer, and replace the top cover with a harder Ross No. 3 aluminum alloy, which can make the cover convex. Xia Zuo leaned over to David with a small stool and pointed to the hybrid engine whose cover had been removed.

"Nonsense, if you add three return pipes, although there will be no more danger of blowing up the return air, the passage space will be reduced, and the steam input flow will be insufficient......" David who was distraught because there was no breakthrough in the research.

"However, removing the spacer and making the hood bulge will add about twenty percent more circulation space, which should ...... That's enough......" Xia Zuo argued in a loud voice, but his voice became smaller and smaller.

It's not that he lacks confidence, but he sees that David's face is not quite right.

......

Tomorrow will officially resume the two watches, which will be effective for a long time, and you can't do live streaming to eat cigarette boxes......