First seismograph

The first modern seismographs were developed in 1848, but the earliest form of earthquake-detecting equipment can be traced all the way back to 132 AD and the Han Dynasty in China. The first device was designed by the then Chinese Astronomer Royal, Zhang Heng, who built a 15 cm (6 in) bronze vessel containing a pendulum. Any minor movement in the ground would cause the pendulum to dislodge balls which would fall into the mouths of bronze toads, signalling an earthquake.