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In the year of 132 A.D., a piece of surprising news caused great
sensation in the capital city (Luoyang of Henan). It was said that the Minister in charge
of historical records, Zhang
Heng, invented an apparatus, which could tell the time and
location of earthquakes. Many people doubted this because they didn't think people could
tell what happened far away in other parts of the world.
The apparatus Zhang Heng invented was called the seismograph, which was
the first one in the world history. According to the records in the Later Han Dynasty
History, that apparatus was cast with bronze. The outer appearance of it was like a jar
with an inner diameter of 8 feet. The mechanism was placed inside the apparatus, and 8
dragons were set in 8 directions outside the apparatus. Each dragon had a bronze ball
in its mouth, and the earthquake waves could make the inside mechanism of the
apparatus start to work and hit the pole on the head of the dragon. Then, the ball
would fall from the dragon to the mouth of a corresponding frog in the direction of the
earthquake. Therefore, the observer could get to know what time and
in which direction an
earthquake had happened.
On March 1, 138 A.D., the dragon in the West of the seismograph opened
its mouth and the bronze ball fell into the mouth of the frog. The seismograph
indicated that
there was an earthquake in the west of Luoyang, the capital city. But since people in
Luoyang did not feel the shock, there were many gossips. Some people even said that
the equipment was inaccurate. Days later, the messenger on horse came to report that an
earthquake had happened in the west Gansu, which was more than 500 kilometers away from
Luoyang. Thus, the seismograph made itself convinced both inside and outside the
courthouse.
The first modern seismograph was made in 1880. The tenet it used was
similar to that of Zhang Heng's apparatus, only that it was made many years later.
The first earthquake observation station in China was established in
1930 and was presided by Li Shanbang. Nowadays, China has built several hundreds of
earthquake observation stations, which makes the earthquake forecast of China rank in the
front row of the world.
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