Zhang Heng seismograph model, stained bone, China, circa late 19th/early 20th century.

Seismograph model made of natural animal bone (imitating ivory), engraved and stained. The surfaces are covered with rich ornamentation, consisting of floral and animal motifs (dragons, horses, fish) and a thread of flames. The egg-shaped body features eight figures of intricately carved dragons, to which eight toads correspond, sitting with open mouths on an octagonal base. The seismograph is topped by a figure of Tao reading the Tao Te Ching. The work is signed on the underside.

The prototype of the model is the world’s first seismometer, constructed in 132 by Chinese scientist Zhang Heng. The device indicated the direction from which an earthquake came, even if the phenomenon took place hundreds of kilometers from Luoyang – the capital of China at the time. The device was about 2.5 meters high and made of bronze. In the mouth of each of the eight dragons was a small iron ball, balancing between the teeth. Inside the body of the device was a metal pendulum, set in motion by the vibrations of the earth. A lever system activated by the pendulum opened the dragon’s mouth, and the falling ball fell into the frog’s mouth. The position of the frog, into which the ball fell, indicated the direction of the earthquake.