Modern seismographs are very sensitive and react to even the weakest tremors. Nowadays, thousands of instruments that can record seismic activity with high accuracy are intact throughout the world. But, as it turned out, a similar device already existed in ancient China almost 2,000 years ago.
Chinese scientist Zhang Heng lived in the Han dynasty in the 2nd century AD. Being a simple official at the imperial court, he was engaged in astronomy, mathematics, mechanics, cartography, poetry and applied art. However, he went down in history as the creator of the world's first known seismograph, which he presented to the emperor in 132 n. er 7 years before his death.
Unfortunately, the seismograph itself has not been preserved. Only his description has reached us. In it, he is depicted in the form of a massive bronze urn or vase. Outside it was decorated with eight dragons, located upside down, in the mouth of which there were balls. Right under the dragons there were 8 bronze toads with mouths open, where the balls were supposed to fall.
In ancient texts, the principle of operation of this device is described very vaguely. Scientists believe that inside the device was a pendulum and lever mechanisms associated with each dragon. In the event of aftershocks, the pendulum began to swing, setting in motion one of the levers.
As a result, a ball dropped into the mouth of the toad from the mouth of the corresponding dragon, telling others not only about an earthquake, but also the direction of propagation of seismic waves, since each toad was oriented to a certain part of the world.
All attempts to accurately determine the principle of operation of the ancient device in the 19-20th centuries were unsuccessful. It remained unclear, for example, how a pendulum could “feel” earthquakes occurring hundreds of kilometers away.js.src = “&version=v2.8”; 'script', 'facebook-jssdk'));