Recently, the word "earthquake" has frequently appeared on the hot search.
Turning over our 5,000-year history of earthquakes, the person standing in the C position is called "Zhang Heng". He and his invention of the "ground motion instrument" seems to be the enlightenment of many children's knowledge of earthquakes.
▲ Zhang Heng, a famous astronomer in the Eastern Han Dynasty.
But questions arise: If the "ground motion meter" is very sensitive to monitoring earthquakes, why is it not widely used today? Instead, this passage about ground motion instruments has been quietly deleted from textbooks. This can't help but raise our questions: can the ground motion instrument really accurately predict earthquakes?
<h1 class="pgc-h-arrow-right" > Zhang Heng and Ground Motion Instrument:</h1>
The geokinetic apparatus in the textbook looks like a wine altar. There were eight dragons attached to the altar, each with a bead in its mouth. When there is an earthquake in a certain direction, the dragon's mouth in the corresponding direction will automatically open, and the beads contained in the dragon's mouth will fall into the mouth of the toad below. The ancients used this device invented by Zhang Heng, a famous astronomer of the Eastern Han Dynasty, in 132 AD to determine that there would be an earthquake in a certain direction.
▲ Foreign leaders visit the ground motion instrument (Wang Zhenduo model).
Historically, it is recorded that the geokinetic instrument successfully predicted an earthquake. That day, a mechanism in a dragon's mouth was triggered. But everyone didn't feel the ground shake, and everyone felt that Zhang Heng had deceived them. However, a few days later, the emissary suddenly sent a letter saying that a major earthquake had occurred in Jincheng and Longxi, more than a thousand miles from Luoyang, and the orientation was consistent with the dragon's mouth of the triggered mechanism. Since then, Zhang Heng has been honored as the first person to be the first earthquake in ancient China.
<h1 class="pgc-h-arrow-right" > why was the geokinetic instrument removed from textbooks? </h1>
In the human-taught textbook before 2010, Zhang Heng and his ground motion instrument were introduced. The text reads:
Scientist Zhang Heng built an instrument that can determine the direction of earthquakes, called a ground motion instrument. This is recognized as the world's earliest seismic instrument.
However, in the 2016 ministry textbook and the 2017 unified textbook, this introduction to Zhang Heng and the ground motion instrument has been quietly removed. Could it be that the ground motion instrument is "not working"?
▲The ground motion instrument model restored by Wang Zhenduo in the textbook is wrong in principle.
Before Xi Qimei answers this question, let's first look at the description of the ground motion instrument in a historical material (too long to look at, directly look at the summary of the little sister).
The Later Han Dynasty Book of Zhang Heng's Biography: "In the first year of Yang Jia, the weather wind and ground movement instrument were restored. Cast in fine bronze, with a diameter of eight feet, the lid is raised, resembling a wine statue, decorated with the shape of a turtle, bird and beast on mount Zhaowen. There are capital pillars, eight paths, Shi Guanfa machine, eight dragons outside, the first steel pill, the toad underneath, and the mouth is open. Its teeth are cleverly made, all hidden in the dignity, and the coverage is endless. If there is ground movement, Zun zhenlong, machine hair spit pills, and toads take the title. The vibration is intense, and the servant is aware. Although a dragon starts a machine, and the seven songs do not move, looking for its aspect is to know where the earthquake is. Test it and be like a god. From the book, there is no such thing. Tasting a dragon machine and not moving, the Beijing scholar Xian blamed it for its lack of signs. A few days later, the earthquake struck Longxi, so they all obeyed. Since then, it is the order of the historian to remember the ground to move from the square. ”
Because the age is too old, Zhang Heng's invention of the ground motion instrument No. 1 machine has long been lost, and he has not left a pattern or detailed description. The ground motion instrument we saw in the textbook before was restored in 1951 by a man named Wang Zhenduo, based on these 196 words, combined with his own imagination. Subsequently, the photos and introduction text of the seismometer were selected for textbooks. But later this ground motion instrument was very controversial in the academic circles, because it was tested in practice, as if it could not be used. In the end, it was determined that the ground motion instrument model, which was restored by Wang Zhenduo in 1951, was removed from the textbook due to the error in the restoration principle. However, we believe that although the ground motion instrument restored by Wang Zhenduo cannot "work properly", it does not mean that the one from more than 1800 years ago is also "unable to work".
▲ The schematic diagram of the geokinetic model restored by Wang Zhenduo in the textbook is now considered to be wrong.
Since then, scientists have worked with historians to find the key points of the problem. In the history books of the record of the earth motion instrument, there is a paragraph that is very ambiguous:
There are capital pillars, eight paths, Shi Guanfa machine, eight dragons outside, the first steel pill, the toad underneath, and the mouth of the mouth.
Although the description of the appearance of the ground motion instrument in the historical data is extremely detailed, what does the opening sentence "there are capital pillars" mean? This "capital pillar" part is obviously the core technology of the geokinetic instrument, that is, its heart. So what kind of design principle is this "heart"? What materials were used? We don't know anything about that.
In fact, in the more than 100 years from 1875 to the present, countless scientists have explored this field. There were 13 conceptual models of geokinetic restoration, including Wang Zhenduo's works, that could not "work properly". After a large number of failed experiments, some people no longer believe in the existence of ground motion instruments.
▲ Feng Rui's team restored the ground motion instrument and schematic diagram, the model is now placed in the hall of the National Earthquake Administration.
But fortunately, over time, our cognition and technology have also continued to advance. In recent years, Feng Rui, a researcher at the China Earthquake Network Center, and his team have discovered 7 ancient engravings of the Earth Motion Instrument before the "Book of the Later Han Dynasty and the Biography of Zhang Heng" was written, indicating that the historical records are not isolated evidence. They firmly believe that the Zhang Heng ground motion instrument must exist and will work. As a result, the work of re-replicating the ground motion instrument was once again put on the agenda.
In 2002, Feng Rui served as the leader of the research group, and the team included experts from the National Museum, Henan Provincial Museum, Beijing Institute of Machinery Industry Automation, Tsinghua University Academy of Fine Arts and other units. After 6 years of cooperation among experts, a working geokinetic instrument was finally restored in 2008. This 1/6 of the original large model is now placed in the hall of the National Seismological Administration.
▲ In addition to the ground motion instrument, Zhang Heng also invented the armillary celestial instrument (above).
So, what is the difference between Wang Zhenduo and Feng Rui's restoration model?
Wang Zhenduo's model: that is, the "Du Pillar" is a cylinder similar to an inverted wine bottle, and the mechanism that controls the dragon's mouth is around the "Du Pillar". This model has been largely rejected.
Feng Rui model: that is, the "Duzhu" is a hanging pendulum (see Yuan Hong's "Later Han Dynasty"), there is a small ball under the pendulum, the ball is located at the intersection of the "meter" glyph slide (that is, the "Guan" mentioned in the "Book of Later Han and Zhang Heng Biography"), when the earthquake, the "DuZhu" moves the ball, and the small ball hits the mechanism that controls the dragon's mouth, making the dragon's mouth open. In addition, the Feng Rui model also changed the toad from facing the bottle to the back to the bottle and acting as the foot of the instrument. The model was simulated and tested, and the results were consistent with historical records.
Do you understand this principle?
Zhang Heng more than 1800 years ago, how strong did you have to be? We were almost driven crazy by you.
What do you think about that? Welcome to leave a message to Sicchi sister and post your thoughts.
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Author: SiqiMei
This article was originally published by the Seacity Museum. Reproduction without permission is strictly prohibited!