Compass is the result of the understanding of the magnetism of objects by the working people of ancient Han nationality 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. 1 1 At the end of the century or at the beginning of the 2nd century, China ships began to use compasses for navigation. Zhou Ping can talk in the Northern Song Dynasty: "The shipowner (helmsman) knows geography, watches the stars at night, watches the sun by day, and watches the compass in the dark."