Take the Beijing subway and go through various interchanges in the network to reach Jianguomen Station. As soon as you come out of Exit C of Jianguomen Subway Station, you can see a high platform on the boundary wall.

The poet Li Bai is the most pro-wine, even if no one to accompany the drink, he also want to "raise a cup to invite the bright moon, the shadow into three people". Li Bai said at the end of this batch of "Four Songs of Drinking Alone Under the Moon" that he would "drink fine wine and climb the high platform by the moon". Although it is true that the platform in front of us has been climbed by many people on the moon, Li Bai was not one of these people. Li Bai is the Tang Dynasty, and this platform is the Ming Dynasty Yingzong Zhu Qizhen's Zhengtong seven years built, that is, built in Li Bai 680 years after the death of the prince.

Li Bai climbed to the platform to do? Su Dongpo in the Song Dynasty said that "the blue even the sky, the evening clouds. The city on the high platform, really transcendent". That is to say, Li Bai went to the high platform to seek transcendence, play a round of drunken boxing and write two drunken poems. The others did not go to the high platform to drink, but to engage in another romantic behavior, that is, to look at the stars, "to see the meteor shower falling on this earth".

Before this Ming Dynasty high platform, people in the Yuan Dynasty had rammed a mound of earth here and then went up at night to look at the stars. One of these people was a very famous one called Guo Shoujing, a regular astronomer. More than a thousand years before Guo Shoujing, during the Eastern Han Dynasty, there was Zhang Heng studying astronomy and geography. Before Zhang Heng, it was usually diviners who could read the stars. After the Eastern Han Dynasty, during the period of the Sixteen Kingdoms of Wu Hu, star-gazing had become a profession called astrologer. I've seen astrologers on the eaves of the house last time I was in an old Zhangbi fort in Shanxi from that period.

You see, the astrologer did not have a high platform to climb, had to build a ladder on the wall outside their house to climb up to see the stars. This Zhangbi Castle astrologer has been separated from the soothsayer's profession, he is neither to calculate the fate of people; nor to calculate the fate of the country. He was to see the orientation of the stars in the sky and then guide the architectural layout of the village.

By the Zhengtong year of the Ming Dynasty, Ming Yingzong Zhu Qizhen ordered people to give the stargazing experts to build the high platform we now see. He allowed the experts to ascend to the high platform to tell the fortunes of people and the fate of the country, all of which were of course his own; and to do some scientific research along the way. At this time, the society has been very progressive, divination is already a fringe doctrine, difficult to reach the hall of elegance. Zhu Qizhen let the experts give Gaotai an official name with academic flavor. In the Yuan Dynasty before this, Guo Shoujing climbed the mound of rammed earth is called "Sitiantai". Astronomers in the Ming Dynasty, "Si Tian Tai" this name is very ashamed of themselves, where can mortals Si Tian? But all can driver is very good. They believe that the sky can not be Division and can only be viewed, they named this platform called "Observatory", is to observe the sky of the platform. This "Observatory" stone is still in the gate above the arch, because of the age, the red color on the word has receded.

The earliest formal observer of celestial phenomena in China was probably Ji Chang, King Wen of the Zhou Dynasty, who compiled the "Zhou Yi", which reads, "The image of the sky is the image of good and bad fortune, and the sage is the image of the sky". The observatory in Beijing was used until the establishment of the Nanjing Zijinshan Observatory in 1927, and was later recognized as one of the second batch of national key cultural relics protection units in 1982.

On the day I came to the observatory, the sky was high and the clouds were light, and the observatory was empty. There are no gatekeepers at the entrance of each place, and I have not seen a house with a "ticket office" plaque. The door to the platform is fully open, saying that since nine o'clock in the morning this is the case, free to visit.

I walked to the door about to move to the platform, see a big man fell on the steps seem to be digging something.

Although I feel that this broad daylight should not be someone digging, or asked him a is not Netflix touch the gold school captain? He said no, he was here preparing to shoot the chaotic clouds in the sky. He complained to me that when he was in the middle of shooting, because he didn't protect the equipment like this, a grandpa came over and pressed the button on his machine, so he shot in front of him for nothing, and the clouds in the sky flew away for nothing. You don't say, there are some old men who are really obsessive-compulsive and can't help but push the button when they see it. That's why all the soldiers in the missile unit are young people, otherwise any old soldier would come over and press any missile launch button, and the missile would fly out at random. Flying to any place, the American troops there will suffer.

When I climbed to the platform, I did not see any old man, but a locked gatehouse.

The first thing you need to do is to get your hands on a few pieces of equipment.

These instruments in 1900 when the Eight-Power Allied Forces invaded Beijing, had been robbed by the French and German armies. The French army hid a few of them in the embassy in China, after two years before returning. The Germans transported the other pieces back to China and put them in the New Palace behind the Potsdam Palace of Solace to show them off, and then returned them to China in 1921 after a defeat in a major war.

Look at the instrument on the stage, this is called "Guiheng Fuchenji".

Look at the beautifully cast bronze.

This Guiheng Fuchen Yi, also known as the Equatorial Warp and Latitude Instrument, was cast by imperial decree in the 19th year of the Qianlong reign in the Qing Dynasty (1754). The guiheng is from "Shangshu" (The Book of the Shang Dynasty), which states that "the guiheng is a jade balance that aligns the seven governments". This Guiheng Fuchen Instrument is slightly more complex than the general equatorial latitude and longitude instrument, with some additional components, mainly to measure the position of celestial bodies (equatorial latitude and longitude) and the time of the sun. In ancient times, there were no atomic clocks, and accurate timekeeping relied on astronomical observations. In fact, nowadays, the time of astronomical observation also prevails, and the atomic clock has to be calibrated with the astronomical time.

This is called ecliptic longitude and latitude.

In the twelfth year of the Kangxi period (1673), it was ordered to be built by the Belgian missionary Nan Huairen to measure the ecliptic latitude and longitude of celestial bodies.

The following celestial instrument was also built by Nan Huairen.

This planetarium is used to demonstrate the position of celestial bodies in the ecliptic and equator, as well as the position of celestial bodies when observed from the ground. Nan Huairen built several planetarium instruments together back then, and so did the following epoch instrument.

Also known as a sextant, the epoch instrument is used to measure the angle between two stars. Although we don't know how it works, we often see people holding such a sextant in their hands when they are sailing on the sea in pictures and drawings. In addition to compasses to guide the direction of navigation, ancient navigation also relied on astronomical observations to locate the position.

The following is a geodesic sextant.

This geodesic instrument was also made by Nan Huairen, and it was used to measure the azimuth of celestial bodies. Nan Huairen built a total of six instruments, including the following quadrant instrument.

The Quadrantiometer was used to measure the altitude angles of celestial bodies.

The following one is a geodesic longitude and latitude instrument.

This geodesic was also built during the Kangxi period, in 1715, the fifty-fourth year of the Kangxi reign. Instead of cast bronze dragons, it has a western style. It was not built by Nan Huairen, but by a German missionary named Ji Li'an. The geodesic meridian integrates the functions of the quadrant and the geodesic meridian.

Above the high platform, most of the elephant viewing instruments were made by foreigners; what about domestic instruments? I walked down from the high platform with the question, and I saw the Ancient Chinese Observatory Instruments right in the courtyard. Take a look at this one below.

Linglong Instrument, which was made by Guo Shoujing's student in the Yuan Dynasty according to his teacher's drawing. That metal sphere is a layer of eggshell, there are many small eyes, people drill into the eggshell, look around, you can see the sky full of stars. Because those small eyes are chiseled according to the system, in which to see the starry sky is very realistic. Beijing Zoo opposite a planetarium, which has a projection hall, modern astronomers put the starry sky with slides projected on the dome of the projection hall, more than this Linglong instrument to see the starry sky is also realistic.

There is also an armillary sphere in the courtyard.

The earliest ancient Chinese armillary sphere was made by the astronomer Lok Ma-tei during the reign of Emperor Wu of the Western Han Dynasty, which is also the earliest armillary sphere in the world. An armillary sphere can be used to measure the equatorial coordinates of celestial bodies. Since the invention of the armillary sphere by Lok Ma-te, there have been many improvements by later generations. This armillary sphere here is from the Ming Dynasty, with many added functions, and it can also measure the ecliptic coordinates and horizon coordinates of celestial bodies. Sixty years after Luk's armillary sphere, a similar observatory instrument appeared in Greece.

There is also a janitorial instrument in the courtyard.

The Simplicity Instrument is a simplified version of the armillary sphere, designed by Guo Shoujing in the Yuan Dynasty. Three hundred years after Guo Shoujing's simplification of the armillary sphere, a simplified version of the Greek armillary sphere appeared in the West, made by a Dane.

The following one I knew it was for measuring shadows as soon as I saw it.

This is called a kui-watch, the standing copper pillar is "ku"; the lying copper plate is "wang". At twelve o'clock in the middle of the day, when you come to admire the scale of the length of the shadow cast by the kyu on the watch, you will know which of the four seasons it is now.

Kei watch can look at the season, look at the time there is also an instrument called "sundial", sundial and kui pronounced similar.

Since there is a sundial in the daytime, there should be a sundial at night, right? You don't say, there really is, but not here. You can only see the sundial through the moon door below.

Here it is.

There was actually a sundial to be the moon sundial's adjutant, because moon sundials are not very accurate in timekeeping, so they need to have an adjutant as a helper. China in the North and South Dynasties when there is the word star sundial, representing the meaning of the moment; but not until the Qing Dynasty appeared moon sundial and star sundial instruments. No sundials and sundials at night how to know the time? It was by listening to the old man beating the clapper.

There were many astronomers in ancient China, and the one we are most familiar with is Zhang Heng in the Eastern Han Dynasty.

Zhang Heng promoted the theory of armillary sphere created by his predecessors and upgraded the armillary sphere invented by his predecessors by installing a hydraulic transmission system. 这个新的浑天仪叫做“漏水转浑天仪”，可以自己行动，按照时间顺序演示天体运动，非常神奇。

Of course, we are most familiar with Zhang Heng's invention, which is also known as the "Geodesic Instrument".

When this observatory was built during the Zhengtong period, there must have been some small rooms built for the celestial officials to rest after boarding the observatory in the morning and evening. That house is still there, the same one from the Ming Dynasty. Because this observatory has been in use, the house has been constantly repaired and is still in good condition.

The main hall is called "Ziwei Hall". In ancient Chinese astronomy, the area around the North Star was called the Ziwei wall, and the name "Ziwei" on the plaque here should have the meaning of observing the sky. Ancient divination in the "Ziwei Douji" said, is based on the birth of the eight characters counting the number of the art, so that this observation and have guessed the Royal destiny and the fate of the country's meaning. Haha, you see, really by me, this gang of watching the sky really have the function of calculating the royal fate.

Although here belongs to the emperor's agency, but the specifications of this house is not high, from the outside is a broad five five ridge gray tile hard mountain roof. This kind of roof east and west urban areas have, even Xuanwu Chongwen have, here to show the noble identity is the huge ridge and both ends of the brick scops owl. Into the house, it is a private house, raised beam structure roof.

This hall is hosting an exhibition of "Starry Sky of China".

There are also some precision machines inside.

This one above is a taxicab, instead of paying the fare by the mile, it looks at how many miles you've traveled. For every mile this car goes, the wooden figure on the car beats a drum. "Eight thousand miles to the clouds and the moon," that is, the colorful clouds chased the moon in this car, and the wooden man on the car beat the drum eight thousand times. Why don't you hire a live person to sit on the car and beat the drum? Who can do this job? Who can handle 8,000 drums? This taxi was also invented by the great Zhang Heng, before Zhuge Liang's wooden oxen and horses.

So many years of walking through the Jian Guo Men, but have always missed the ancient observatory, today's trip to finally see its back and the back of the bronze, these bronzes are of course contemporary replicas.