Today, seismologists use sensitive equipment to record tectonic movements deep within the earth and analyze this data to predict earthquakes. Although seismometers are becoming more advanced each year, accurately predicting earthquakes is still an inexact science. More than 2,000 years ago, however, an ancient Chinese inventor, Zhang Heng, made the world’s first seismoscope which proved to be incredibly accurate. Called the Houfeng Didong Yi, Zhang Heng’s seismoscope was made in the shape of ajar with eight tubes extended from a circle of dragon heads on the exterior of the jar. When the device detected an earthquake, a small ball fell out of one of the dragon’s mouths and into the mouth of a toad figure affixed to the base of the jar. The toad indicated the direction the seismic wave was traveling.