The "Dragon Jar" was invented by Zhang Heng, an inventer of Han Dynasty more than 1000 years ago. It could measure if an earthquake occurred and in which direction.
If for ancient China, (i am assuming because you said did) it is seismograph
It may have been the Chinese inventor's Zhang Heng's seismoscope .
A seismometer.
Dragon jar
Used to measure earthquake activity with sound waves.
they used a seismograph
If for ancient China, (i am assuming because you said did) it is seismograph
A seismometer is used to measure the strength of earthquakes.
It may have been the Chinese inventor's Zhang Heng's seismoscope .
A seismogragh and/or seismometer.
A seismograph is an instrument used to measure the strength of earthquakes.
Seismograph
A seismometer or seismograph will measure the amplitude and frequency of seismic waves which are produced by earthquakes.
the seismograph
A seismometer.
Dragon jar
Seismometer (or seismograph) and it measure seismic waves