Seismoscope

The first Seismoscope invention was unveiled in 132 CE. Under the name “Houfeng Didong Yi”* Imperial Historian Zhang Heng presented his invention to the Han Court.

Descriptions of the first seismoscope were shaped like a barrel, equipped with eight dragons clinging onto the vessel facing downward at set intervals, each carrying a ball within its mouth. Beneath each dragon a frog is seated, mouth open in anticipation, in the event that the device detects an earthquake. Unlike the wooden replica that is housed in the Cultural Centre Museum, the original Seismograph was said to have been 6 feet in diameter and forged in bronze.

As intricate as the design was, historians are unsure of how the Seismoscope device functioned. One theory suggests that a thin rod is carefully balanced within the centre of the device. When detecting an earthquake, the rod falls in the direction of the tremors causing the dragon to drop the ball into the mouth of an assuming frog. The sound of the ball dropping into the frog's mouth would alert those nearby to the seismograph's activity, while the position of the dropped ball would indicate the earthquake's direction of origin. The device was unable to measure the magnitude of the earthquakes.