Examples of traditional inventions in China

The manufacturing technology of compass was first proposed in "Mengxi Bi Tan" by Shen Kuo (1031-1095 AD).

Shen Kuo pointed out that small iron needles ground on magnets have relatively stable magnetism, so he decided to use this artificial magnetic needle instead of natural magnets to make pointing tools. Shen Kuo discussed four methods of magnetic needle devices, and he also discovered magnetic declination in the process of making compasses.

He wrote: The magnetic needle "often points slightly to the east, but not entirely to the south." This is an important discovery in the history of magnetism. With the compass, ocean navigation became possible. So for early navigators, the compass was a priceless treasure.

The discovery of magnetic phenomena

The Chinese working people in the pre-Qin era have accumulated knowledge of magnetic phenomena. When exploring iron ore, they often encountered magnetite, that is, magnetite ( The main component is ferric oxide - chemical formula Fe3O4, also known as iron oxide black, magnet, magnet. It is a magnetic black crystal, so it is also called magnetic iron oxide).

Several chapters of "Guanzi" have already recorded these discoveries: "If there is a magnet on the mountain, there is gold and copper underneath." There are similar records in "Shan Hai Jing". The iron-attracting properties of magnets have been discovered very early. In the nine-volume mastery chapter of "Lu's Spring and Autumn Annals", it is stated: "Charity attracts iron, or attracts it." The ancients called "magnetism" "compassion". The ancients regarded the magnet's attraction to iron as the attraction of a loving mother to her children.

He also believes: "Stone is the mother of iron, but there are two kinds of stones: kind and unkind. A kind stone can attract his children, but an unkind stone cannot attract." Ancient people before the Han Dynasty wrote magnet as "Charming Stone" is the expression of loving-kindness stone

. In the Western Han Dynasty, there was an alchemist named Luan Da. He used the properties of magnets to make two chess pieces. By adjusting the polarity of the two chess pieces, sometimes the two chess pieces attracted each other and sometimes repel each other. Luan Da called it "fighting chess". He presented this novel gadget to Emperor Wu of the Han Dynasty and demonstrated it on the spot. Emperor Wu of the Han Dynasty was so surprised that Long Xin was so happy that he named Luan Da "General of Five Benefits".