What was the name of China's early compass?

Compass, called Sina in ancient times, is mainly composed of magnetic needles installed on the shaft. Under the action of natural geomagnetic field, the magnetic needle can rotate freely and keep in the tangential direction of magnetic meridian. The south pole of the magnetic needle points to the geographical south pole (magnetic north pole), and the direction can be distinguished by using this property.

It is often used in navigation, geodesy, tourism and military affairs. The invention of the compass with physical direction indication has three parts, namely Sina, compass and magnetic needle, all of which belong to the invention of China. According to ancient mine records, it first appeared in the Cishan area during the Warring States Period.

Extended data:

Sina background

The earth is a big magnet, and its poles are close to the geographical south pole and the geographical north pole respectively. When the magnets on the surface of the earth can rotate freely, they will indicate the north and south because of the nature that the magnets repel each other and attract each other-this truth was not understood by the ancients; But this phenomenon has been discovered by the ancients.

The ancients regarded magnets attracting iron as the attraction of loving mothers to their children. And think: "Stone is the mother of iron, but there are two kinds of stones: kind and unkind. Kindness can attract his children, but not kindness. " Before the Han Dynasty, the ancients wrote magnets as "Ci Shi", which was a sign of love for stones. In the Western Han Dynasty, there was an alchemist named Luan Da. He used the characteristics of magnets to make two things like chess pieces. By adjusting the mutual position of the polarities of two pieces, sometimes two pieces attract each other, and sometimes they repel each other. Luan Da called it "playing chess". He dedicated the novel to Emperor Wu of the Han Dynasty and gave a live demonstration. Emperor Wu of the Han Dynasty was pleasantly surprised. He was named "General Five Blessingg".

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