Zhang Heng's Seismoscope Invention

In 132 CE, Chinese polymath Zhang Heng presented the first seismoscope to the Han Dynasty court in Luoyang. The bronze device, called 'Houfeng Didong Yi', featured eight dragons with metal balls in their mouths positioned above eight toads. When earthquakes occurred, an internal pendulum mechanism caused one dragon to release its ball into a toad below, indicating the earthquake's direction. In 134 CE, the device detected an earthquake in Gansu province over 500 km away that was not felt in the capital, enabling the government to send aid to the affected region.