Introduction of compass of four great inventions

The compass is a simple tool to judge the direction. Originally known as Sina. The main component is a magnetic needle that can rotate freely on the shaft. The magnetic needle can be kept in the tangential direction of magnetic meridian under the action of geomagnetic field. The north pole of the magnetic needle points to the geographical north pole, which can be used to identify the direction.

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.

Extended data

Inventors, the crystallization of ancient working people, can't be elegant, but we can find clues from a large number of historical documents. There were guiding tools in the Warring States period. In the Spring and Autumn Period, people can make porcelain from nephrite and jadeite. In the Eastern Han Dynasty, Wang Chong's works were also recorded. Shen Kuo talked about various phenomena caused by friction magnetization in the supplementary talk of Meng Qian's Bi Tan.