When did Sina first appear in Cishan, Hebei Province?

Sina first appeared in Cishan, Hebei Province during the Warring States Period.

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. Understand the results of magnet magnetism in 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.

The working people in the pre-Qin period in China have accumulated their understanding of magnetic phenomena. When they are looking for iron ore, they often encounter magnetite, that is, magnetite (the main component is Fe3O4, alias iron oxide black, magnet, magnet, also called magnetic iron oxide).

These findings have long been recorded in several articles in Guanzi: "There is a magnet on the mountain, and there is gold and copper under it." There is a similar record in Shan Hai Jing. The iron-absorbing property of magnets was discovered long ago, and the nine volumes of Lu's Spring and Autumn Annals are proficient in: "Kindly absorb iron, or absorb it." The ancients called "magnetism" kindness.

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".