The destruction and devastation left by the recent Nepal earthquakes is still sweeping through the media, but something many people might not know is that the first seismograph was actually invented in China as early as the Eastern Han dynasty (25-220 AD). Its inventor, Zhang Heng 张衡 was a scholar specializing in astronomy and mathematics from Nanyang 南阳, Henan province. Accounts have described him as a quiet and calm person, who generally kept to himself. He studied diligently and also wrote poetry.
At the time, it was popular belief that earthquakes were an unlucky sign, and that they represented Heaven’s anger. There was deep belief in the ancient Chinese branch of philosophy which centered around the balance between the two forces of Yin and Yang. Earthquakes were seen as a symbol of this balance being upset, often due to poor actions taken by rulers. In fact, a lot of earthquakes that occurred in ancient times have been particularly well documented because historians believed it was important to record such an inauspicious day.
Through his studies in science, Zhang Heng developed a good understanding of processes, such as meteorology and calendar calculations. These led him to believe that earthquakes were in fact a natural phenomenon.
The instrument that Zhang Heng invented looked like this:
Original image courtesy of Baidu
If an earthquake occurred, the initial tremors on the ground would cause the detector to shake, and the ball would fall from the dragons above into the mouth of the toads, making a large clanging sound as it landed. The genius thing was, it could also actually indicate the direction from which the quake was coming, for example if the ball fell from the easternmost pointing dragon, it would imply the earthquake was coming from the west. As well as this, the seismograph is a particularly artistic artifact, as can be seen from its appearance. The use of dragons and toads also played into the philosophical element of the time; dragons represented the Yin and toads the Yang, the relationship between them and the balance between ‘up’ and ‘down’. Even with all his rigorous scientific foundations, Zhang Heng was still incorporating traditional beliefs into his creation.
Unfortunately, as has been the fate of many scientists throughout world history, it was one thing to build his invention out of his discoveries, but another for it to be accepted by his peers. Zhang Heng presented his seismograph to the Emperor Shun Yang Jia 顺帝阳嘉. The reaction at court was first mainly of disbelief. In 138 AD, Zhang Heng’s seismograph detected an earthquake in the Longxi 陇西 area (present day west of Gansu province). It was proved correct when a few days later it was reported there really had been an earthquake there. Even after this, many still did not trust Zhang Heng, and in fact, often feared him. It had been known before for people to take advantage of the superstitious beliefs to cause trouble at court. It is unsurprising, then, that his invention was not too easily accepted.
Image courtesy of www.cultural-china.com
History has been a little kinder, and Zhang Heng is now remembered as a successful mechanical inventor whose ideas were ahead of his time. His other inventions included an armillary sphere, a south-pointing chariot, and a form of calendar. On his tombstone, his friend Cui Yuan 崔瑗 had written: “数术穷天地，制作侔造化” (He had all knowledge of mathematics and art in the world, his inventions matched a great creator), strong praise for the depth and profundity of his knowledge and skills.
The original seismograph has actually been lost. However Chinese and foreign scientists alike have been researching Zhang Heng’s work and reconstructing his invention. Recent testing declared the seismograph able to detect earthquakes with an impressive amount of accuracy even by modern standards. Today, a reconstruction is kept in the Exhibition Hall of the Museum of Chinese History in Beijing. It would not be until 1700 years later that a similar instrument was invented elsewhere. Another scientist whose strong legacy is not necessarily reflective of the skepticism and suspicion he received while alive.
For more cool things you didn’t know were invented in China, try our previous article.
Main image courtesy of Baidu