The HouFeng Seismograph
In ancient time, people believe earthquakes are punishment from god, so some people are killed or recalled. Earthquakes gradually became the political ploys, and the HouFeng Seismograph also led to the trough of Heng Zhang`s career.The HouFeng Seismograph shows on the picture above is made by Heng Zhang in 132 A.D. There is 8 Chinese dragons scattered on the Seismograph, with a bronze ball in the mouth of each of them. There are also a toad under each of them, with their mouth open. When earthquakes happen, the bronze ball pointing to the earthquake direction will drop into the mouth of toad.
The creator of this HouFeng Seismograph, Heng Zhang, is a great astronomer, geographer, inventor, and Mathematician. Heng Zhang`s achievement produced an enormous influence to developing scientific field at ancient time. For instance, Heng Zhang created the first armillary sphere that uses water as power to rotate the same speed as Earth, because he supports the theory earth is look like an egg. Another instrument he made is South-pointing chariot, which chariot with a statue on top of it always pointing to the south.He also contribute to study of math, such as the first person who calculate the tenth digit of π. However, we are only going to talk about his achievement in earthquakes prediction this time.
An ancient Chinese armillary sphere
The model of the South-pointing chariot mad by Heng Zhang
The HouFeng seismograph was made by bronze, which 2.7m wide looks like an urn.The machinery in it is very complicate, so it cannot be rebuild by scientists until 2005. There is a pendulum on the centre of the seismograph, and when earthquake happen, the primary wave will affects the seismograph and the pendulum will wobbles and triggers the gear the opens the mouth of dragon.
At the beginning, people do not believe this urn like thing could measure earthquake, because people think earthquake is the punishment by gods. However, the reality proved Heng Zhang`s invention. Once, the dragon faces to west direction dropped the bronze ball, but nothing happened in Beijing, so tongues began to wag. Several days later, the messager from LongXi, an area in eastern China, turn to government for help in earthquake, and people start to believe how amazing the seismograph is.
This map shows the distance between BeiJing and LongXi. The red dot is LongXi, and the Blue dot is BeiJing.
The HouFeng Seismograph cannot report the intensity, nor specific position, but it is a starting point in human history to predict earthquakes. Even though it cannot warning people an earthquake, it could help government to rescue victims. This is a great invention, but also led to tragedy of Heng Zhang. Those officials in government of ancient China uses earthquakes as the reason to frame up their opponent, therefore Heng Zhang caused damages to the benefit of aristocrat and put himself into a political conflict and lose to aristocrat.
