Geography
Compass
Measurement of
Earthquakes
Compass
Compass is one of the four important Chinese inventions. As we all
know, it is the device for showing directions.
Invention of Compass
In the
Period of the Warring States, the Chinese discovered that some stones called
loadstones today had magnetism and could show the directions of north and
south through attracting iron and steel. The chinese shaped these pieces
of loadstone into a spoon and called it
si-nan(¥q«n).
They would put the
si-nan
onto the centre of the "di-pan(¦a½L),
a polished square board with directions marked on it. Then, the handle
of the si-nan would point to the north once it was let free. This
was the ancient type of compass.
Development of Compass
Though the si-nan
could help to distinguish the directions, the loadstones lost their magnetism
quite often and made the invention an imperfection.
When it came to the Song Dynasty, the Chinese learned to make
artificial magnet. They then put fish-shaped thin pieces of 
magnetised
steel onto a bowl of water. Then the fish head would point to the north.
Later on, the great Chinese scientist Shen-kuo(¨H¬A), hang
a magnetic needle balanced on two sides with a piece of thread and wax.
The needle hence would not fall and could rotate freely and show the direction.
This hang-up compass basically set a model for the structure of modern
compasses.
Importation of Compass to other places As navigation and external
trade were developed quickly in the Song Dynasty, the compass was
used in nautical transportation soon after it was invented. According to
the records made in the past, compasses had been commonly used by ship
owners in China since early twelfth century. With the help of the compasses,
the Chinese ships could sail to Korea and Japan in the east, to countries
in South East Asia in the south, and had built close and strong trade bonds
with Persia and Arabian countries.
Later on, the compass was imported to the Europeans through the Arabians.
This not only boosted to world navigation development, but also contributed
much to the Europeans' great voyages of discovery.
Measurement
of Earthquakes
In the Eastern Han Dynasty, the famous scientist Cheung Hang invented
the magnificent earthquake detector, Hou-feng-di-dong-yi(Ô·¦a°Ê»ö).
Invention of Hou-feng-di-dong-yi
This invention was made of copper. It had the outline of a big barrel,
with eight dragons fixed on the wall of it, each facing a compass point.
Below each dragon, there would be a crouching toad with an open mouth.
Once an earthquake happened at a certain direction, the mouth of the dragon
facing that direction would open and the copper ball inside would fall
into the mouth of the toad below. According to a historical record, this
machine had a very high degree of accuracy. It was said that on one day
in 138 A.D., people in Luo-Yang(»Ü¶§) did not
notice any occurrence of earthquake, but the ball in the mouth of the dragon
facing west fell suddenly. Many people suspected in this machine's accuracy.
However, a few days later, an ambassador from Long-Xi(Ã÷¦è),
which was a thousand miles away, came to report that there was an earthquake
in Long-Xi. However, this machine was lost during wars. the model
we see nowadays are just models made by people afterwards.
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