Posted on 07/28/2025 10:42:49 AM PDT by Red Badger
Modern reconstruction of the Houfeng Didong Yi. The Chinese Museum Calgary Alberta/Wikimedia Commons
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Chinese scientists are exploring the possibility of recreating a modern, more sophisticated version of an ancient earthquake sensor allegedly invented nearly 2,000 years ago.
The original, called the Houfeng Didong Yi, was, according to Chinese lore, invented in 132 AD by the famous Chinese polymath Zhang Heng. This is widely considered the world’s first dedicated seismoscope (earthquake detector).
However, claims around the existence of this device have been questioned in recent years, with many citing that it was too advanced for the time.
The Houfeng Didong Yi (meaning “instrument for measuring seasonal winds and Earth’s motion”) supposedly consisted of a bronze jar with eight dragons facing eight compass directions. Each of these dragons held a ball in its jaws and sat above a toad with an open mouth.
When an earthquake happens, the dragon facing the quake’s direction drops its ball into the toad’s mouth, acting as a kind of ancient directional indicator.
World’s first seismoscope
Despite being historically praised, many modern scholars have dismissed the device as a legend. To this end, textbooks in China removed any reference to it in 2017.
A researcher named Xu Guodong, from the Institute of Disaster Prevention in China, has re-examined the historical texts and attempted a realistic reconstruction using modern seismic science and engineering knowledge.
His new model features a central pendulum (like a weighted stick anchored in the ground) that swings when an earthquake occurs. It also has an L-shaped lever system that transfers the pendulum’s motion to one of the dragons’ ball-release mechanisms.
The reconstruction also features a locking system that ensures only one ball drops per quake, preserving directional accuracy. The new detector works by allowing the pendulum to swing when an earthquake occurs.
This pendulum, in turn, triggers a lever that makes one dragon drop its bronze ball. Like the original, the ball falls into the waiting toad’s mouth, indicating the direction of the quake.
The device’s locking system stops the other dragons from reacting, so only one direction is shown. According to Xu’s calculations, the device could detect tiny tremors as small as 0.5mm of ground movement.
To this end, it effectively amplified ground motion via the pendulum to increase sensitivity. While it couldn’t always determine the exact epicentre (modern wave science shows some limitations), its directionality was likely reliable under the right conditions.
Rediscovering ancient knowledge
According to historical records, the device was not just a curiosity, but it actually worked. For example, a real historical case from 138 AD reports that the device detected an earthquake 528 miles (850 km) away before anyone in the capital felt anything.
Later records show that after 132 AD, Luoyang (the capital at the time) began to record many more earthquakes, likely due to the device’s increased sensitivity. The physical device and its plans have since been lost to time.
“The loss of the seismoscope [original device, diagrams and notes missing] was [likely to have been] directly caused by war and chaos. It was also linked to powerful noble families who [might have] coveted, fought over, and hid the device and its technical records,” Xu explained.
“In Chinese history, only two bronzes were ever deified: the Xia dynasty’s Nine Tripod Cauldrons … and this – a testament to its extraordinary historical significance,” he added.
Following this research, Xu’s team plans to rebuild the device using only Han dynasty methods and materials. By doing so, they plan to restore a lost legacy and acknowledge early Chinese contributions to science that predate the West by over 1,700 years.
PinGGG!......................
Bat boy is the chief engineer.
THIS is exciting!
When I worked at the Adler Planetarium, I used to catalog the oldest astronomy books and polish gold and silver astrolabes. One thing that fascinated me was the oldest alarm clock. It was made from a sundial and a cannon.
“However, claims around the existence of this device have been questioned in recent years, with many citing that it was too advanced for the time.”
Yeah because the earth did not have gravity until recently... lol
"Ancient Chinese secret." I remember seeing an artist's conception of this legendary gizmo in one of those coffee table books, probably the Time-Life series.
That MIGHT wake me up......Used to live next to a railroad track...............
My limit was 300 lbs for the rock and the poles were from straight willows.
It could detect earthquakes if such occurred at that time.
What kind of dog did the Jetsons have?
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An ASTRO-LAB!................
Wifey and I were in Alsace Lorraine in France, got an Airbnb, nice old church across the street, 5AM ding dong ding dong. Asked the owner, what’s up with the early church bells, he said what bell? You can get used to anything after long enough.
Works with smells, too.
Across the street from my house is now a park, but used to be a open-tank sewage treatment plant there.
The smell was intense.
After about a month or so we couldn’t smell it anymore...............
“””””One thing that fascinated me was the oldest alarm clock. It was made from a sundial and a cannon.”””””
I had one of those, the apartment complex evicted me before I had even had my first cup of coffee.
Clever! Never watched it.
Dog's name is Astro..................
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