Who invented the compass in Song Dynasty?

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The compass was invented by Sina.

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 north pole of the magnetic needle points to the north pole, so this property can be used to identify the direction.

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.

Compass is the result of China ancient working people's understanding of magnet magnetism in long-term practice. As one of four great inventions of ancient china, its invention has played an inestimable role in the development of human science, technology and civilization. In ancient China, the compass was first used for rituals, etiquette, military affairs and divination, and to determine the orientation when looking at geomantic omen.

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Related theories of compass:

In Lun Heng, it is not pointed out that Sina is a magnetic spoon. And as soon as we realized that the magnet attracts iron, we found that its finger polarity did not conform to the cognitive law. In addition, we should make magnets into magnetic spoons that can guide us and consciously polish them in the north-south direction. Before the invention of the compass in the 11th century, there was no description of the poles of magnets and their finger polarities in ancient literature.

In 1950s, Academician Qian, entrusted by Guo Moruo, tried to make a spoon-shaped Sina with natural magnets, but failed because of the small magnetic distance and large friction at the bottom of the natural magnets. Mr. Wang Zhenduo's recovery is that tungsten steel is magnetized in artificial electromagnetic field, which was impossible more than two thousand years ago. Now Sina's model is no longer on display at the China History Museum in Beijing.