Its predecessor is Sina, and its 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, and the south pole of the magnetic needle points to the geographical north pole, so people can use this property to identify the direction.
Compass is constantly improved in the process of use, during which there are many creations, such as the discovery of magnets and archaeological use. The predecessor of compass is Sina, one of the four great inventions in ancient China, and its invention is the result of our working people's understanding of the magnetism of objects in long-term practice.
People in ancient China came into contact with magnetite due to productive labor and began to understand its magnetism.
After many experiments and studies, a practical compass was finally invented.
During the period of Emperor Wu of the Han Dynasty, it is well known that Emperor Wu loved rare treasures. If you can find one or two things to please him, you will never enjoy the glory of your life.
At that time, there was an alchemist named Luan Da who made two pieces by using the special properties of magnets. By adjusting the mutual position of two pieces, sometimes the two pieces attract each other and sometimes repel each other.
Luan Da called it "playing chess".
Emperor Wu of the Han Dynasty saw a lot of chess, gold, agate and ivory, and everything was needed in the world.
So as soon as he saw this pair of chess, he immediately lost interest and didn't believe that there was anything unusual in this dark iron knot.
Luan Da didn't explain much, but simply said, "Your Majesty, watch this." Say, take out a few pieces from the bag and gently put them on the chessboard.
A strange thing happened. Suddenly, like alive, small pieces automatically collided and fought on the chessboard until Emperor Wu of the Han Dynasty was dumbfounded. It took him a long time to recover and he couldn't help wondering.
When Luan Da saw that he was happy, he felt smug and hung his hand to one side, waiting for the reward from Emperor Wu of the Han Dynasty.
Emperor Wu of the Han Dynasty was surprised and named Luan "General of Five Benefits".
In fact, it is not surprising that chess pieces attract each other. Luanda only made full use of the iron absorption function of the magnet, and Emperor Wu of the Han Dynasty didn't know it.
There are many such stories.
According to the biography of Ma Long in the Book of Jin, Ma Long led his army westward into Gansu and Shaanxi, and piled up magnets on both sides of the narrow path that the enemy had to pass through.
When enemy soldiers wearing real armor passed by, they were firmly absorbed and could not move.
Malone's soldiers wear rhinoceros armour, and the magnets have no effect on them, so they can move freely.
The enemy thought the magic weapon would retreat without a fight.
China's understanding and utilization of magnetism in ancient times is relatively early in the world, and it is recorded in many ancient books. Ancient people knew magnetism from the discovery that magnetite was magnetic.
The ancients called magnetite "magnet" and "magnet", and also called magnetite subspecies with strong magnetism "Xuan Shi".
According to the Records of Foreign Objects in the Eastern Han Dynasty, there are some reefs and shoals around the South China Sea islands containing magnets, which often attract ships to be "blocked by iron leaves", making it difficult for them to get out.
During the Wei, Jin, Southern and Northern Dynasties, our ancestors already had a lot of knowledge about the properties of magnets.
Even Cao Zhi, a poet at that time, used the phrase "a magnet attracts iron, but gold is not connected" in his poems, which shows that he also understands the essence of a magnet.
Tao Hongjing of Liang Southern and Northern Dynasties put forward the magnetic survey method in Records of Famous Doctors. He pointed out that excellent magnets are produced in the south and have strong magnetism, which can absorb three iron needles and make them hang on the magnets end to end.
Magnets with stronger magnetism can attract more than 10 iron needles, and can even hold devices weighing one or two kilograms.
Tao Hongjing not only pointed out the strength and weakness of magnetism, but also pointed out the measurement method.
This may be the earliest magnetic measurement record in the world.
The ancients' understanding of magnets was embodied in medicine.
In the process of observing and studying magnetic phenomena, ancient ancestors further understood the properties of magnetism and tried to apply these properties more. For example, there are records that magnets have been used to treat diseases in past dynasties.
According to Guanzi and Lv Chunqiu at the end of the Warring States Period, the ancients in China discovered that a stone on the mountain had the magical property of absorbing iron more than two thousand years ago, and they called it a magnet.
Shennong Materia Medica in the Eastern Han Dynasty mentioned that rheumatism, joint pain, fever and deafness were treated with magnets with cool taste.
During the Southern and Northern Dynasties, Tao Hongjing also talked about magnets nourishing kidney, strengthening bones and benefiting qi, dredging joints, eliminating carbuncle and reducing swelling in his medical book "A Bielu of Famous Doctors".
Sun Simiao, a medical scientist in the Tang Dynasty, mentioned in Qian Jin Fang that honey pills made of magnets can improve eyesight if taken frequently.
Wang Huai, a medical scientist in the Northern Song Dynasty, also said that a magnet can cure children from swallowing needles by mistake, that is, a big jujube stone is used to polish the magnet, put on silk thread and put it in the throat, and then suck out the swallowed needles.
In Fang Jisheng, a medical work strictly used and written by doctors in the Southern Song Dynasty, it is also talked about using magnets to treat ear diseases with poor hearing. This is to put a bean-sized magnet in the ear with new cotton, and then put a pig iron in the mouth to improve the hearing of the sick ear.
In Compendium of Materia Medica written by Li Shizhen, a famous pharmacist in Ming Dynasty, the description of medical magnets is rich and summative, and the shape, main therapeutic names, drug preparation methods and various uses of magnets are described in great detail.
For example, the diseases treated by magnets include earache, deafness, kidney deficiency, senile deafness, senile asthenia, blindness and cataract, infantile convulsion, uterine failure, proctoptosis of large intestine, abscess of golden sore, bleeding of golden sore, swallowing needle iron by mistake, toxic heat swelling, and various toxic swelling. Drugs made of magnets include Cizhu Pill, Zi Xue Powder and Erlong Zuo Ci Pill.
Generally speaking, the medical books of various dynasties often recorded that magnets were used to treat many diseases.
The research and utilization of magnets by our ancestors was the initial basis for the invention and development of compasses.
In fact, the invention of the compass is the result of ancient ancestors' observation and research on magnetic phenomena.