Zhang Heng's geodesic was removed from the textbooks, what did the CAS members say about this?

Because the geodesic in the textbook is just a replica, not the real one.

The geodesic is a special instrument invented by Zhang Heng to detect earthquakes in advance.

The whole structure is made of refined copper and looks like a wine jar. With an ornate appearance, there are eight dragons engraved on the outside of the main body, each with a precious pearl in its mouth. Beneath the eight dragons are eight toads with their mouths open upwards, waiting to contain the orb. Once an earthquake occurs, the orb in the mouth of the dragon in the corresponding direction will fall into the mouth of the toad below. When we saw the picture of the geodesic instrument invented by Zhang Heng when he was in middle school and understood its principle, we were all amazed. We didn't realize that someone had invented an instrument to detect earthquakes thousands of years ago.

But the actual geodesic instrument invented by Zhang Heng has not been preserved.

The real geodesic instrument was destroyed or disappeared before 200 AD. The picture of the geodesic instrument we see in textbooks was designed by Wang Zhenduo, the former director of the museum department of the Ministry of Culture, after more than a year's hard work, and is known as ? Wang's geodesic instrument? Later, major newspapers and book compilers immediately printed the pictures of Wang Zhenduo's geodesic instrument in their books. Although it took Wang Zhenduo more than a year to restore the geodesic, it actually took 15 years from his design to its final completion. But could this thing really detect earthquakes? This is what has been questioned.

The history books only say that it can only know the direction of the earthquake, not an instrument to predict the time of the earthquake.

But it is also considered the greatest invention of ancient times. After all, at that time, the information transfer is slow, can greatly facilitate the earthquake relief. According to historical data, the seismograph predicted that an earthquake would occur more than a hundred years later. After this historical record, no other actual earthquake facts have been recorded in any historical documents.

Since the 1960s, many famous and authoritative experts in various countries have begun to question seismographs. Japanese scientists used scientific principles to prove that the principles of seismographs are not valid. But it is still great that our ancient people invented this instrument 2000 years ago.