First, the controversy about Zhang Heng's ground motion instrument
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, a closed lid, shaped like a wine bottle, decorated with the shape of a turtle, bird and beast of The Seal Mountain, with a capital pillar, a pong shape of eight paths, and a shiguan hair machine. There are eight dragons on the outside, the first copper pill, and 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 stirred, 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. Since its examination, it is 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.
The ground motion instrument has been lost, the source of the above text is "Later HanShu Zhang Heng Lie Biography", the main point is that Zhang Heng ground motion instrument is to use the column (du column) to detect the earthquake, the seismic sensitivity is even higher than the human seismic sensitivity, and the column will be correctly reversed to the direction of ground movement after the earthquake.
Wang Zhenduo made the first ZhangHeng ground motion instrument model in New China in 1951. For decades, this model has been published in textbooks and stamps, and in the 1980s, the Chinese government also gave a cloisonné zhangheng ground motion instrument model as a gift to the United Nations World Intellectual Property Organization in Geneva, and has long been exhibited in its exhibition hall as the top invention of ancient human science and technology. An image of Zhang Heng's geokinetic instrument also appears in the emblem of the China Earthquake Administration. However, the ground motion instrument restored by Wang's is only a static model and cannot actually detect earthquakes.
Since 1969, some articles questioning and criticizing Zhang Hengdi's strict wording have appeared in foreign publications [1]. Those articles write that, after experiments by scholars from several countries, it has been concluded that it is impossible for the ground motion instrument to test the earthquake with a column, on the grounds that we cannot make a very sensitive column stand at all. For an insensitive pillar that can be stood, after being shaken in a certain direction, it will not often fall in the direction of the shock, but will fall in all directions. That is, by the inverted direction of the column, it is impossible to judge the direction of the shock. Therefore, the record of Zhang Heng's ground motion instrument in Chinese history books is either wrong or false. Some people also believe [2] that the almost absurd example of the emergence of ground motion instruments in the history of ancient Chinese science and technology shows that the attitude of China's predecessors to science and technology is quite incorrect, so that China's scientific and technological progress stagnated and lagged behind the West after the Renaissance. A foreigner who claims to be a fan of Zhang Heng points out in his book [3] that there is no scientific principle of Zhang Heng's ground motion instrument that can explain it, and that it was invented by Chinese.
In order to refute the negative remarks that are unfavorable to the reputation of Zhang Heng ground motion instruments, the China Earthquake Administration set up a "Zhang Heng Ground Motion Instrument Scientific Restoration Research Group" at the beginning of this century. However, after several years of research, the group echoed the negative remarks of foreign countries that questioned Zhang Heng's ground motion instrument, and also believed that the column seismic test was impossible, and only the suspension [4] proposed by the British seismologist John Milne could be successful [5]. So the research group made several pendulum ground motion instruments that did not match the historical records, and they are still exhibited in some science and technology museums.
After the research group announced their results, Fang Zhouzi, a well-known anti-counterfeiter, also questioned or denied the authenticity of Zhang Hengdi's motion instrument [6]. One of his reasons was that if the sensitivity of a pillar was higher than that of a person, then the person next to the ground motion instrument only needed to stomp his foot, and the column would fall. The disadvantage of this practice is that the anti-interference ability is very poor, and it is impossible to distinguish between earthquakes and earthquakes caused by construction, vehicles, pedestrians, etc.
In the years around 2010, the group's claims led to many negative reports that were unfavorable to Zhang Heng's ground motion instrument. Suddenly, there were a lot of negative remarks in the media accusing Zhang Heng of moving the instrument as false, and the reputation of the Zhang Heng ground motion instrument suddenly fell to the bottom, which had quite serious consequences: abroad, the United Nations World Intellectual Property Organization removed the Zhang Heng ground motion instrument model in its exhibition hall; in China, the Ministry of Education not only deleted the content of the ground motion instrument in the middle school textbook since 2017, but even deleted the introduction to Zhang Heng in its entirety.
Second, whether the column seismic test is feasible
The author has 50 years of experience in the development of precision instruments for astrometry. The author believes that the ground motion instrument made by Zhang Heng was a precision instrument at that time and should have an exquisite design. However, scholars who have previously studied this problem have treated the seismic column as an ordinary architectural column, such as:
In his thesis [7], Sekino of Japan argued that force could prove that it was impossible to test the shock of a column, because of course the column was thinner and more sensitive. Thus, if the sensitivity of a column is higher than that of a person, the diameter of the column with a height of nearly 2 meters calculated by force is as thin as 1.5 mm. Obviously, such a thin and tall (copper wire-like) column is absolutely untenable;
The second example is that the Ground Motion Instrument Restoration Group also believed in their paper [5] that the columns of buildings in the Qin and Han dynasties were extremely thick, and the thick columns could not be sensitive to earthquakes.
The author believes that the column must be treated as a precision instrument in order to recognize the necessary structure and related mechanical conditions of the seismic column.
Figure 1. Ground motion instrument column structure
The structural and mechanical requirements for the seismic column are (see Figure 1):
The tall and thick column must have a very small ground, so that the column can be unstable and fall under a very weak ground action;
The small ground of the column must be a precision-machined extremely hard (such as sapphire) plane (or other face shape). This small material cannot be made of a column body material (such as bronze) that is not hard enough, otherwise its edges will be crushed by the extremely large pressure of the column when it is dumped.
The support surface under the ground of the column must also be a precise hard plane, and this support surface should also be adjusted to a fairly high level. Therefore, the support plane must have a leveling mechanism;
The gravitational vector of the center of the column must fall exactly in the center of the column that is smaller than the ground, otherwise the heavy column will fall in all directions after being shaken (that is, it will fall in the direction of the column that has been randomly placed in the direction of the direction). In order to meet the above requirements, the column should have an adjustment device for the position of the center of gravity, so that before standing on the column, the column should be adjusted for the balance of gravity.
In order for the column to be able to detect earthquakes, the following mechanical conditions should also be required:
If the sensitivity of the seismic column a is better than the highest sensitivity of human earthquakes (the seismic boundary generally uses this value of five-thousandths of gravitational acceleration), it can be proved by mechanics [8] That the radius of the column on the ground and the height of the column center of gravity h should meet the relationship a = (r / h) g<0.005g. This formula states that the r/h of the column should be less than 0.005;
The spokes of the (horizontal) ground movement of the inverted column must be greater than the (approximate) diameter of the ground;
The (horizontal) vibration period of the earthquake must be greater than about 2 seconds, and the reciprocating and reciprocating action of the column in too short a period will be exactly offset by each other.
Figure 2. The author of this article and his restoration of the prototype of the ground motion instrument
Since 2013, the author has used rigorous mechanical analysis to finally prove that the column seismic test is correct in terms of mechanical principles, and has made a physical model (see Figure 2) to confirm that its principle is also feasible in practice.
In response to the so-called saying that stomping on the foot will cause the column to fall over and cannot detect the earthquake at all, the author has taken a video, as follows:
In the video, the experimenter can be seen jumping next to a sensitive column, but the column can still stand, because the floor vibration caused by human beating is mainly a vertical vibration. But seismic waves produce both vertical and horizontal vibrations. As shown in the video, as long as the person blows a breath on the column (the interference amplitude of the person blowing the column should be less than the interference of the pole of ground motion, but the interference in the horizontal direction can be simulated), the column will fall. This video proves that a pillar that is sensitive to detecting earthquakes can really resist the interference caused by the actions of the person next to it.
At this point, the reader should understand why Chinese and foreign scholars who have studied the seismic test of the column before cannot successfully test the earthquake with the column. However, Zhang Heng before 1800 was able to successfully apply the principle of column seismic testing to his ground motion instrument, and we can't help but marvel at the high level of Zhang Heng's science and technology.
3. Restore the reputation of Zhang Heng's ground motion instrument
Since the negative remarks in the society that deny Zhang Heng's ground moving instrument have lasted for ten years, it is now necessary to make unremitting efforts to restore the reputation of Zhang Heng's ground moving instrument. Over the past few years, the author of this article has done the following work for Zhang Heng's ground motion instrument:
In 2014, he published the book "The Mystery of Zhang Heng's Ground Motion Instrument".
In 2016, in cooperation with the Chinese Society for the History of Science and Technology, an academic appraisal meeting was held on the theory of seismic testing of Zhang Heng's ground motion instrument column, which was unanimously recognized by the participating experts.
Three generations of large-scale Zhangheng geokinetic demonstrators have been developed before and after, of which the second generation demonstrator is used for the appraisal meeting in 2016, and the third generation (see photo) demonstrator will be used to show to the media. Readers who need a live video of the third generation of Zhang Heng's ground motion demonstrator work can ask the author for it.
In 2020, he published an important paper on the seismic test of Zhang Heng's ground motion instrument column in academic journals [8].
The author believes that Zhang Heng is one of the greatest scientists in ancient China, and his ground motion instrument is also an outstanding invention and deserves an important position in the history of science and technology in the world. I call for the restoration of the reputation of the Zhang Heng ground motion instrument, its re-inclusion in the history textbook, and the re-donation of a Zhang Heng ground motion demonstrator to the relevant United Nations organizations.
bibliography:
【1】见Boit, B.A., Earthquake, A Primer, W. H. Freeman & Co., New York, 1978; Sleeswyk, A.W. &Sivin, V., Dragons and Toads, The Chinese Seismoscope of A.D.132, Chinese Sciences, Vol.6, pp.1-19, Philadelphia, 1983
【2】Qian Wenyuan, The Great Inertia--Scientific Stagnant in China, Croom Helm, Sydney,1985
[3] Leopold Leeb, Zhang Heng. Science and Religion, 251-252[M]. Beijing: Social Sciences Academic Press, 2000.
【4】J. Milne, Earthquakes and Other Earth Movements, D. Appleten & Co., New York, 1886
[5] Feng Rui et al., questioning the traditional model of the ground motion instrument [J]. Studies in the History of Natural Sciences, 2006, Vol.25 (Supplement).
[6] Fang Arkzi: Speaking of whether Zhang Heng's geokinetic instrument works, http://blog.sina.com.cn/s/blog_4bf6b2ba0100nsch.html, 2010-12-15 20:14:20, checked on September 2, 2021
[7] Seki No-yo, Marquis of Zhang Heng 's Wind and Ground Movement Instrument (hereinafter omitted in Japanese) [A]. The 25th anniversary of the founding of the Oriental Society. Proceedings of Oriental Studies [C], Oriental Society. 1972，433-439。
[8] Hu Ningsheng, Restoration and Research of Zhang Heng Ground Motion Instrument Column Seismic Test [J]. Journal of the History of Science and Technology in China, Vol.41, No.3, 2020.
About author:Hu Ningsheng, former director of Nanjing Astronomical Instrument Factory, has long been engaged in the development of precision astrometric instruments, and has published three mechanical science books in recent years.
Manuscript Editor: Zhao Yuhao
Source: Guangming Network