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• Si Nan

Over 2,000 years ago, in the Warring States Period (475-221BC), Chinese ancestors invented the earliest compass -- Si Nan, also known as the South Pointer.

• Different from the compass of today, Si Nan was composed of two parts: a spoon and a tray. The spoon was cut from an intact piece of natural loadstone, with its handle as the South Pole and its round, smooth bottom as the center of gravity. The tray, on the other hand, was made of bronze , and at the center, there was a round, smooth groove. When the spoon was put into the groove, it would rotate. When 
  Pointing-to-the-south fish made by Cheng Yuanliang of the Yuan Dynasty 
  the spoon stopped, its handle would point to the south, and its head to the north. This instrument was the predecessor of the magnetic compass. However, since it was easy for natural loadstone (magnetic iron oxide) to lose its magnetism, Si Nan could not be widely used.
• Pointing-to-the-South Fish

During the Northern Song Dynasty (960-1127), artificial magnetization was discovered, giving rise to the Pointing-to-the-South Fish, which was made from a piece of thin iron sheet cut into the shape of a fish, magnetized in a geomagnetic field, and put into water, floating and lying north-to-south. However, due to its weak magnetic field, Pointing-to-the-South Fish was not of much practical value.

• Marine Compass

Through magnetizing a steel needle by rubbing it on a natural magnet, people invented the earliest artificially magnetic compass, which pointed south when floated on water or suspended. Later it was attached to a bowl with directional points.

The compass was soon employed in navigation. The earliest record on using the compass in navigation was in Zhu Yu's Ping Zhou Ke Tan (written between 1119-1125), which recorded Zhu Yu's experiences in Guangzhou (South China's Guangdong Province ), where navigation was highly developed.

Zhu also wrote about some of the experienced sailors, "The sailors know how to pinpoint the ship's position; they watch the stars at night and the sun in the day, and when it is cloudy, they use the compass." This might be the earliest record on the use of the compass in the world's navigational history. Initiated by the Chinese people, this navigational instrument was a grand innovation in navigation technology.

Soon after, Arabian sea boats also employed the navigation device, and went on to introduce it to the European countries. As Friedrich Engels, a famous Marxist philosopher, pointed out in his book Natural Dialectics, "The magnetic needle arrived in Europe via the Arabs in around 1180." The statement shows the Europeans applied the compass in navigation 80 years after the Chinese.

The famous scientist Shen Kuo (the author of Dream Creek Notes) of the Northern Song Dynasty discovered the existence of magnetic declination (the angular deviation of a compass needle from true north), after performing many scientific experiments. He pointed out correctly that the magnetic poles of the earth were not in uniformity with the geographic poles.

The use of marine compass and the theory of magnetic declination combined played a most important role in the long-distance sea voyages. For the first time in history, humans were able to navigate freely under any kind of weather conditions. Hence many new sea routes were opened to traffic, promoting the exchange of culture and trade among the people of the world. Words fail to describe the compass' importance to navigation.

Joseph Needham, a famous historian, once said to Chinese students: "In the realm of navigation, your ancestors were much more advanced than our ancestors. Far before Europe, the Chinese already harnessed the wind power, with the coordination of fore (front) and aft (rear) sails to navigate in any direction of the wind they encountered. Perhaps for this reason, in the history of navigation, China never used the galleys, which were rowed along by slaves as in ancient Greece or Rome."