Houfeng Didong Yi

Nicholas Choi

Blog # 2

China is and was a nation plagued with frequent earthquakes. Being located in one of the most active seismic regions, earthquakes have been occurring throughout their long history. During the late 100 AD an inventor, Zhang Heng, made the world’s first seismoscope. This mechanism was a large urn made of bronze and had a diameter of two meters. Being the first of its kind, Houfeng Didong Yi (the seismoscope) was dependant on a balance system. This ancient seismoscope is an example of Asian innovation. This mechanism utilized a heavy pendulum in its core, which acted as a motion sensor. When the urn is shaken by an earthquake the pendulum has inertia high enough to withstand the movement of the urn thus tilting, this causes it to activate one of the eight sides. When tripped it would activated a lever that opened one of the dragons’ mouth and dropped a metal ball into the mouth of a frog figure. It could accurately tell the direction from which the epicenter of the earthquake was from hundreds of miles away. This instrument was created so that authority could properly respond to earthquakes and send aid quickly to the affected villages. It is recorded that once this seisoscope detected an earthquake somewhere "towards the eat" but none was felt in the city. A couple days later a messenger reported one in the location that the instrument had detected.

At the time the Chinese were unaware that earthquakes were caused by shifting tectonic plates. Instead they believed that they were caused by disturbances and shifting of cosmic yin and yang. Much of Chinese culture and knowledge of the world dictated what and how they designed. Philosophies of yin and yang acted as a foundation for many Chinese inventions, so much so that it has affected and ultimately formed much of what has become the Asian aesthetic. Themes of balance and action/reaction are recognizable in almost every aspect of Chinese ingenuity ranging from their instruments, such as this seismoscope, to their architecture, to even their rituals. Even today Asian design utilizes these philosophies but globalization has drastically changed the style and technology they use. The seismoscope built by Zhang Heng has expanded beyond China and has been the foundation for much of the seismic technology we have today.