Most people in China refer to themselves ethnically as Han, the largest of several ethnic groups making up the country’s population. The Han Dynasty was the second imperial dynasty of China and flourished, with a brief interruption, from 206 BC to 220 AD. This time span is often referred to as the “Golden Age” for China. The Han Dynasty ushered in a period of renaissance in promoting innovations such as a new method of producing better paper, the wheelbarrow, glazed pottery, hot air balloons, and an early version of a seismograph. Zhang Heng, a court astronomer, had devised the first known seismograph. When an earthquake occurred, the bronze jar would shake open the dragon’s mouth and cause a ball to fall into the toad’s mouth directly beneath it. This device had a limited range in detecting distant earthquakes, but it worked well enough on a local level.
