Back to Ming Dynasty with Industrial Revolution System

Chapter 1450 Establishing an Observatory

"Master, do you want to talk to me in detail? That is really my honor. When I arrive in the capital, I will be there whenever you are called." Li Jinde said unexpectedly when he heard that Chu Yun wanted to ask him to know about the affairs in Europe. .

"That's right. After all, even a person with excellent insight like the military leader finds it incredible after hearing about your experience. He wants to know the details of the matter to help him make a better judgment on the situation in the West." Congjun said the man from the ministry.

Li Jinde nodded, and then he led everyone to the train station in Tianjin Wei.There have been many solid stone buildings in Tianjin Wei. These buildings are usually made of cement or masonry by the government, and there are relatively high floors of three or four floors, which surprised Li Jinde.

At this time, Tianjin Wei has changed a little in three years and a big change in five years. It is changing at a very fast speed, and it is somewhat different from before Li Jinde left.

Of course, the real upheaval is not as simple as it seems on the surface. The technological changes behind it occur in factories, colleges and other places that are difficult for ordinary people to touch.

The Academy of Astronomy at the Imperial University Hall announced a major event, gathering talents from all over the empire who devoted themselves to astronomical research.After Selina joined the Huaxia nationality, she was transferred from the overseas department to a regular academy, and she chose the Astronomical Academy.

But this is also normal, astronomy is not metaphysics, not some impractical science.In fact, farming civilization relies on astronomy to formulate calendars, and great voyages rely on astronomical knowledge to determine the position of ships during the voyage.

"Our navigation industry has achieved unprecedented development, and precise longitude indications are urgently needed for maritime navigation. The Astronomical Academy intends to build a new observatory at the southern foot of Yanshan Mountain, to correct the celestial body movement star catalog and the position of stars. It is also responsible for measuring the correct longitude. At the same time The observatory built during the Zhengtong period will no longer be used after the new building is completed. Astronomical instruments such as the armillary sphere, simple sphere, and armillary phase, and houses such as the Ziwei hall and the sundial shadow hall will be preserved as a commemoration of ancient astronomical achievements .” The dean of the Astronomical Academy announced the plans of the Astronomical Academy to the students.

When the students below heard the news that the observatory was going to be established, they couldn't help showing joyful expressions.

To set up a special observatory, it means to configure a new telescope, which is of great help to formulating the lunar calendar or studying planets, longitude and latitude!
"There are two other important things you need to know. The first thing is that we will use a new type of refractor telescope. This new type of refractor telescope uses an achromatic lens and can replace the long-body telescope we currently use."

"Achromatic lens?! Can the chromatic aberration problem of the lens be solved?!"

Selina especially didn't understand: "How to solve the chromatic aberration problem of the astronomical telescope?"

"Chromatic aberration is indeed a big problem. The light we observe from the universe and the light we see in our daily life is actually polychromatic light. When red light and blue light pass through the lens of the telescope, the refractive index is also different, and the light of different colors converges. At different focal lengths... so the astronomical images we observe will inevitably have color spots or halos. In order to obtain good observation results, the refracting telescopes we use now need to use lenses with very small curvature, and the mirror body is especially long. "

"Our physicists have developed a new type of compound lens, which consists of a convex lens made of crown glass and a concave lens made of flint glass. How does the light refract when it is shot from the side?"

While introducing the new telescope technology to these students, the dean guided them step by step, hoping to let them learn to analyze problems by themselves.

He drew the structure of the compound lens with chalk on the blackboard.The idea is very simple, a convex lens and a concave lens close together to form a composite lens.But is such a seemingly simple technological innovation really as simple as putting two things together?

"Salina, come up and draw the refraction road map of light in the compound lens." The dean asked Selina to come up among the crowd.

"Yes!" Selina had never seen such a compound lens, but she was not completely at a loss.

The beauty of science lies in the search for the most basic knowledge to build up the building of human civilization step by step, just like stacking blocks.When people abandon the thousands of years of making tools based on experience and start trying to penetrate the essence of the problem, then they have entered the era of the technological explosion.

For example, if you master the principles of mechanics, you can analyze the force of everything. The principles of optics are very important in the application of optical telescopes.

Selina tried to draw with chalk the propagation of different colors of light in different media and lenses. As she personally tried to analyze the propagation of light in the compound lens, she gradually showed an understanding expression.

Obviously, when the light passes through the compound lens, the light of different colors converges at one point, and the focal length is not far away.That is to say, the problem of chromatic aberration can be better solved without a long mirror body!

"What a clever method!" Selina was shocked when she saw the final result.

Not only Sarina, but other students of the Astronomy Academy were shocked by the results of the final analysis.They have roughly known the method of achromatic aberration through basic analysis!

"You can know the refractive index and dispersion coefficient of crown glass and flint glass, the refractive index and refraction angle of different colors of light in different lenses, and you can basically draw the route of the beam in the compound lens by hand. It seems that your The mastery of the basic skills is very solid, and you are worthy of being a student of our Astronomy Academy." The dean looked at his students with satisfaction.

Selina, who came from Britain, had been exposed to the theories of Galileo and others before, so she had some foundations in physics, coupled with her studies at the Astronomy Academy, she already had a considerable reserve of knowledge.

To put it bluntly, the knowledge she knows is unheard of by Galileo and others in this era.

"Now you know why you combined a convex lens made of crown glass with a convex lens made of flint glass?" asked the dean.

Selina stared at the analysis diagram on the blackboard: "Yes! Crown glass makes a convex lens with low dispersion, and flint glass makes a concave lens with high dispersion. Two different lenses are placed next to each other so that the chromatic aberration of one can be determined. The other cancels out. But the positive lens optical power of crown glass will not be canceled out by the negative lens of flint glass. The compound lens is still a convex lens as a whole, which can gather light of different colors on the same focal point, but eliminates The color difference in it!"

(End of this chapter)