The first rain of winter finally fell, and it was two days at a time.

Roland leaned back at his desk, looking out the window at the hazy town. The rain was swept up by the wind and slapped on the glass one after another, causing ripples. Under the refraction of the ripples, the outline of the town becomes distorted. The extension of the house and the street is bent and deformed, and it is no longer in order. Due to the lack of effective drainage measures, the dog-toothed stone pavement is overflowing with water, and from a distance, it looks like many sparkling streams.

The mountains and forests in the distance are obscured by the mist, looming like a world of confusion.

If such a scenery is put in modern times, it must be a tourist attraction, and now Roland wants to see more of a steel and concrete jungle. The construction of the city wall had to be halted when it rained, which made his joy a little less than that he had succeeded in "persuading" the envoys of the fortress the day before.

"You just said that the air around us is made up of many gases, really?"

A clear voice interrupted Roland's thoughts, and Anna asked with a wink of her pretty blue eyes.

"Ahem, Miss Anna, you should use honorifics when addressing Your Highness," the chief knight reminded him.

"Don't be so particular," Roland turned, "she's my student now. Taking advantage of the rain, he summoned the two witches and Carter to listen to his lesson—yes, he decided to start a general science course. The fact that the stone craftsman Karl ran an academy inspired him, and even the stonemasons could open a school, not to mention his own engineering mechanical dog. Why is there discrimination just because of ignorance? Education for all is the most effective means of promoting the development of civilization in any era.

He originally wanted to call the assistant minister, but the other party has been busy with government affairs recently, so he politely declined. For some reason, Roland felt that Barov was particularly motivated after the winter, and almost single-handedly provoked the daily management of the border town.

When she heard that there was something new to learn, Anna immediately became bright, and her eyes seemed to glow. Nanawa was also very happy to see that she didn't need to treat all kinds of experimental animals, and Carter came to listen with you with a look of being idle and idle.

But not long after the class began, the knight's eyes were glazed. Nanawa was also ignorant, staring at the words nature and science in a daze. Anna seemed to be half-understood, but she struggled to write down everything she heard. Roland had to pause and let the three of them digest for a moment.

He smiled and nodded in response to Anna's question, "Of course, even though they look the same. ”

"Your Highness, I don't understand, since they all look the same, how do you know it's a different gas?" Carter questioned.

"I can prove it to you. ”

Roland knew that if he only told it in words, he was afraid that most people would be dizzy by these theories that sounded mysterious. He decided to pique everyone's interest with a simple experiment.

A candle, a glass, a wooden basin, a bowl of clear lime water—this was something he had prepared in advance, and although the glass was a pale brown color, far less transparent than the beakers of later generations, it was barely enough. After all, this simple experiment does not require observation of the process of change.

Roland had done it once before, and the results of the experiment proved that although there was magic in this world, the rest of the natural rules were still the same as those on earth. He asked Anna to light the candle and set it up in a wooden basin.

"Combustion requires the consumption of a gas, which is also relevant to all life, and if we stop breathing, it will be like this candle. "Roland pressed the glass to the candle, and the flame shook twice, and soon it was extinguished.

"It runs out of air, Your Highness, it's not surprising," said the chief knight disapprovingly, "of course we'll die without air, like falling into the water." ”

Nanawa nodded repeatedly.

"So, you think there's nothing left in the cup?" Roland asked, pouring lime water into the wooden basin, and the line of water quickly flooded the rim of the cup, and finally stopped halfway through the cup.

This experiment is so classic that most elementary school teachers like to use it as an initiation experiment for nature interest lessons. Roland still remembers the shock brought to him by the teacher's demonstration and explanation on the lectern at that time, and since then he has embarked on the road of no return to science and engineering.

He gently lifted the corner of the cup, only to see a few bubbles instantly emerge from the mouth of the cup and emerge from the water.

Then, the clear lime water appeared slightly cloudy, and a little white suspended matter slowly spread from the mouth of the cup.

"If there was nothing in the cup, we wouldn't see bubbles and changes in the surface of the water. This means that there are at least two different gases in the air. In fact, the burning of candles consumes only one part of the air, and the other part cannot participate in the combustion. Although it is as colorless and odorless as the former, it is diametrically opposed in nature. ”

"Seeming...... It seems to be so," Carter thought for a long time before he figured out the relationship between the two, "but what's the use of knowing this?"

"If we can get the former, we can make the flame burn longer, and likewise, if we get the latter, we can extinguish the flame quickly!" Anna said suddenly.

It's a genius, Roland admired in his heart, although there is a slight fallacy, but from the different properties of the gas, he can immediately associate it with the use of separation and purification, this idea is definitely genius-level. Knowing that she had not received any systematic modern education, the quick thought of this was enough to show that her logical skills were beyond the ordinary—at least far better than her own chief knight.

"It is well said that since humans learned to use fire, they have been separated from animals, and the origin is only an accident. Perhaps it was thunder and lightning that set the trees on fire, or maybe it was the sparks that burst out from the impact of stones that caused the flames. But if no one notices this, if no one tries to exploit it, we are still like wild beasts," he said, "to show you that curiosity and thinking are the driving forces of human progress. There are many such potential forces in nature, just waiting for us to discover and exploit them. ”

After saying this, Carter still looked skeptical, and Nanawa belonged to the type of unconscious, looking at Roland with stunned eyes. Only Anna lowered her head, as if thinking about something.

Well, Roland sighed, indeed, ideas that were too far ahead of their time would not be shocking, they would only make people feel confused. The height of the mind determines that it is impossible for them to understand the power of that power, and only when the real thing is really placed in front of them will they know how amazing the hidden power in nature is.

At that moment, the kettle hanging from the mantelpiece rattled as it steam hit the lid.

"Ah, the water is boiling," said the knight, as he walked over and took out the kettle with his fork, and the sound soon stopped. He wrapped a rag around the handle and filled the cups with water in his jug.

For example, Roland reached out to hold the cup, feeling the temperature coming from the wall of the cup. From the first day fire is exploited, its principle is ripe. "Boiling water" has been witnessed and practiced by countless people, but they did not expect that this wisp of gently raised water vapor can also contain amazing energy.

This driving force, which would not be grasped by mankind until hundreds of years later, changed the history of mankind in a very short period of time. Although the principle is simple, it is limited to process problems and is not the first choice for most people to farm. But he was different, he thought, there were witches in this world. Fighting with magic is nothing more than the idea of a barbarian...... Using magic to create and replace some key crafts that curb the progress of civilization is the right way to use it.

After chatting until the sun went down and having dinner with everyone, Roland returned to his bedroom.

In this era, there is no nightlife at all, and if you don't make people, everyone goes to bed earlier. He also considered whether to use the prince's privilege to recruit a maid to do sports, but in the end he was too thin-skinned to say it.

As soon as he lit the candles in the room, he heard several applause from behind him, and then someone spoke, "What a unique lesson, I didn't expect that His Royal Highness the Fourth Prince is actually a learned man." ”

It was a strange woman's voice. Roland's cold sweat broke out in an instant, and the stranger who could appear in his room without knowing it, what else could it be besides an assassin!? He rushed to the door with his legs, and before he could put his hand on the doorknob, a cold wind blew through his ears in an instant. When he came to his senses, a silver-handled dagger was firmly stuck in the door, the dagger just a finger's width from his cheek.