From which dynasty did the compass begin to be used?

As early as 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.

Sina is the earliest magnetic conductor. The name "Sina" began in the Warring States Period (475 BC-22 BC1year) and ended in the Tang Dynasty (665438 AD+08 AD-907 AD). Because Sina's ancient meaning has been constantly evolving, it has forged an indissoluble bond with a series of ancient inventions.

The earliest document that recorded Sina was Guiguzi, which wrote: "Zheng people take jade and will take Sina's car because they are not confused." As can be seen from the records in Guiguzi, in order to avoid getting lost, Zheng people must take Sina with them to "get jade".

In the mention of Sina, Chong Wang's account number is the most important. He clearly pointed out: "Sina's shovel, thrown to the ground, is its guide." "Spoon" means spoon. Sina should be a magnetic director with this "guide". However, the "land" here refers to the "ruins" in the ancient mechanical disk. The mechanical disk was invented in Qin and Han dynasties and used for games or divination. There are 24 directions around the site, and the symbol of the Big Dipper is engraved in the center.

The invention of compass should be the result of gradual improvement over a long period of time, and the forms in different periods should appear in different forms. In the Tang Dynasty, the activities of scholars of geomancy were quite active, and they began to emphasize the choice of direction, so it became a top priority to find a more convenient pointing device than a magnetic spoon. So the iron pointer and floating magnetic needle in the shape of iron guide fish or tadpole came into being.

Qiu Yanhan, a geomancer in Shaanxi Province who lived in the Kaiyuan period of the Tang Dynasty (7 13-74 1), was praised by later geomancers as the earliest founder of the three needles (straight needle, sewing needle and middle needle) in geomantic theory. Zhu Quan, Ning Xianwang of Yahao Science and Technology in the Ming Dynasty, said in his Secret Book of Magical Machines: "The method of acupuncture has never been handed down from ancient times." It is Zhang (about 730- about 8 10), a Taoist priest in Jinhua, Zhejiang Province in the Tang Dynasty. His Taoist name is Xuanzhenzi, and he wrote twelve volumes of Xuanzhenzi, with three volumes left. From this remnant, I know that he is quite good at physics, but I can't find any records directly related to compass or needling. But this symbol can't help but remind people that tadpoles are called "mysterious needles" in Jin Cuibao's Notes on Ancient and Modern Times. Its text says: "Squid, tadpole, mysterious needle, abstruse fish, round, with a big tail, feet are born when the tail falls." In the 10th century, there was a similar record in Ma Su's Notes on China in Ancient and Modern Times. This record seems to link the invention and application of the magnetic needle with the compass fish in shape and performance.

The method of making guide fish can be found in The General Theory of Jason Wu compiled by Ceng Gongliang and others in the Northern Song Dynasty. In the fifteenth year of the first volume of Jason Wu, the law said, "Cut it with thin iron leaves, which are two inches long and five points wide, and the head and tail are like fish. Burn to red in charcoal fire. Take the iron pot and the iron pot fish as the initial fire, straighten the tail, dip the basin, and stop it. " This method is to magnetize the iron sheet by using the geomagnetic field. It is known that the fish-shaped iron sheet is slightly inclined downward, which is beneficial to magnetization. In fact, the influence of the so-called magnetic dip angle in modern science has been discovered. When in use, the compass fish floats on the water, which conforms to the principle of water floating magnetic needle.