Sina is the earliest magnetic conductor. The name "Sina" began in the Warring States Period (475 BC-22 BC1year) and ended in the Tang Dynasty (665438 AD+08 AD-907 AD). Because Sina's ancient meaning has been constantly evolving, it has forged an indissoluble bond with a series of ancient inventions.

In China's azimuth culture, it has gone through three stages, namely, astronomical positioning, making Sina by magnetic method, and finally evolving from Sina to compass, followed by the continuous progress of azimuth determination technology.

Extended data:

Compass principle

The earth is a big magnet. The poles of the earth 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.

China's magnetic needle and compass spread to the west by land and water successively, which had a great influence on the progress of human civilization. Historians believe that the water compass with a magnetic needle floating in the water comes down in one continuous line with the compass, which was invented by China. 1985 The dry compass held by the figurine "Zhang" unearthed from Zhu Jinan's tomb in Linchuan, Jiangxi Province in the Southern Song Dynasty proves that the invention right of the dry compass also belongs to China.

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