As early as 1550, Italian mathematician Jerome Cardin was the first to point out that China's "three great inventions" had an impact on the world: Sina (compass), printing and gunpowder. And think that they are "no invention in ancient times can match them."
1620, the British philosopher bacon also mentioned in his book "New Tools": "The three great inventions of printing, gunpowder and compass have changed the whole face and situation of things all over the world."
Then in 186 1 ~ 1863, Marx and Engels pushed the significance of these inventions to a peak. Marx wrote in the application of machinery, natural forces and science: "gunpowder, compass and printing-these are the three great inventions that predict the arrival of bourgeois society." Gunpowder shattered chivalry, the compass opened the world market and established a colony, while printing became a tool of Protestantism, a means of scientific rejuvenation in general, and the most powerful lever to create the necessary premise of spiritual development. "
Engels clearly pointed out in the German Peasant War: "A series of inventions have more or less important significance, among which gunpowder has glorious historical significance. It has been undoubtedly confirmed that gunpowder was passed from China to Arabs through India, and was introduced to Europe by Arabs and gunpowder weapons through Spain. "
Maddox, a British sinologist, pointed out: "For a long time, the inventive genius of China people has been manifested in many aspects. China's three great inventions (navigation compass (Sina), printing and gunpowder) provided extraordinary impetus for the development of European civilization. " Compass is a simple tool to judge the direction. Originally known as Sina. The 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. The north pole of the magnetic needle points to the geographical south pole, which can be used to identify the direction. It is often used in navigation, geodesy, tourism and military affairs. N of the compass refers to the north, e to the east, w to the west and s to the south.
China is regarded as the country that invented the compass in the world. The invention of the compass is the result of the long-term practice of the working people of Han nationality in China. Due to productive labor, people came into contact with magnetite and began to understand its magnetism. People first discovered the property that magnets attract iron, and later discovered the directivity of magnets. After many experiments and studies, a practical compass was finally invented. The earliest compass was made of natural magnets, which shows that the working people of Han nationality in China discovered the attraction of natural magnets and their iron very early. According to ancient records, as early as the Spring and Autumn Period and the Warring States Period, the productive forces developed greatly, especially agricultural production, which promoted the development of mining and smelting industries. In the long-term production practice, people know magnets from iron ore. The earliest compass was Sina. "China's earliest compass theory is the" induction theory "based on the theory of Yin-Yang and Five Elements." According to Guan Zengjian, Shen Kuo, a great scientist in China in the middle of the1/kloc-0 century, is still puzzled by the compass. His "Meng Xi Notes" introduced the artificial magnetization method of the compass, the discovery of the magnetic declination angle and the erection method of the compass, but he didn't know why the compass was guided-"guided by a magnet" ... it couldn't be justified! Subsequently, scholars put forward various compass theories based on the theory of yin-yang and five elements and people's understanding of the shape of the earth at that time. For example, Guan's Geography refers to Mongolia, which was written in the Song Dynasty at the latest, first put forward the following logic:
"Magnetic needle is made of iron, and iron belongs to gold. According to the five elements, gold is born in water and the north belongs to water, so the water in the north is the son of gold. Iron comes from magnets, which are bred by the spirit of the sun, which belongs to fire and is located in the south, so the south is equivalent to the mother of magnetic needles. In this way, the magnetic needle should not only take care of the mother, but also miss the children, naturally pointing to the north-south direction. "
The compass principle of the Southern Song people still thinks that "the compass refers to the spirit where the sun is located" only revolves around the phenomenon of magnetic declination, and the argument is based on the coordinate system that turns to geographical orientation-the ancients in China thought that the ground was flat and limited in area, so there must be a center on the ground, and the meridian passing through the center is the only north-south direction. Zeng Sanyi, a member of the Southern Song Dynasty, believed that once the geodesy is not on this north-south line, the compass points to nature "less biased". In the Ming Dynasty, it was pointed out that the correct guiding direction was determined by the earth azimuth system, and the deviation angle was determined by the celestial azimuth division system. Guan Zengjian believes that this statement "embodies the embarrassment of traditional compass theory in the face of the contradiction between yin-yang induction theory and magnetic declination".
During the Wanli period of the Ming Dynasty (A.D. 1573 ~ 1620), missionaries came to China, bringing western compass theory, earth theory and related scientific and technological knowledge. Influenced by it, China scholars began to explore the compass theory from a new angle. In this process, the functions of Yin-Yang and Five Elements are gradually weakened, and the analysis from the mechanical point of view is increasing. However, the scientific theory put forward by Gilbert in 1600 is not unified in western academic circles, let alone in the East. Among the missionaries, ferdinand verbiest, a Belgian Jesuit who came to China in 1658, has the most systematic compass theory, but he thinks that the magnetic needle points to the geographical north and south poles of the earth itself, and his theory is still limited to the scope of ancient science, unlike Gilbert who realized that the earth itself has magnets. Ferdinand ferdinand verbiest's theory had a far-reaching influence in China. Until the middle of19th century, some scholars in China still used it to explain the compass problem. At this time, missionaries who came to China in the late Qing Dynasty began to introduce modern western magnetic knowledge to China.
In the pre-Qin period, our ancestors had accumulated a lot of knowledge in this field. When exploring iron ore, they often encountered magnetite, that is, magnetite (mainly composed of ferroferric oxide). These findings have long been recorded. These discoveries were first recorded in several articles in Guanzi: "There are magnets on the mountain and gold and copper under it." There are similar records in other ancient books, such as Shan Hai Jing. The iron-absorbing characteristics of magnets have long been discovered. The main chapter of the nine volumes of Lu's Spring and Autumn Annals is: "Kindly absorb iron, or absorb it." At that time, people called "magnetism" "kindness". They think that magnets attract iron is 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. " It is said that after Qin Shihuang unified the six countries, Epang Palace was built near Xianyang. There is a door made of magnets in the palace. If someone wears armor and hides weapons to assassinate in the palace, they will be attracted by the magnet door. This story tells us that the ancient working people mastered the knowledge of magnetism very early.
When two magnets are put together and close to each other, sometimes they attract each other and sometimes they repel each other. As we all know, a magnet has two poles, one is called N pole and the other is called S pole. Like-sex repulsion, opposites attract. People didn't know this truth at that time, but they could still perceive this phenomenon.
In the Western Han Dynasty, there was an alchemist named Luan Da. He used this characteristic of magnet to make something similar to two chess pieces. By adjusting the mutual position of the polarities of the two pieces, sometimes the two pieces attract each other and sometimes 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". Luan made great use of the properties of magnets to make novel things to deceive Emperor Wu of Han Dynasty.
The ancestor of the compass appeared in the Warring States period. It is made of natural magnets. It looks like a spoon with a round bottom, which can be balanced on a smooth "field" and can rotate freely. When it is at rest, the handle of the spoon will point to the south. The ancients called it "Sina", and in the book Han Feizi at that time, there was: "Wang Li Sina took the time first." "Sooner or later" means square, east. Guiguzi recorded the application of Sina, and Zheng people took Sina with them when picking jade to make sure they didn't get lost.
In the Spring and Autumn Period, nephrite and jadeite with hardness of 5-7 degrees can be polished into various shapes, so natural magnets with hardness of only 5.5-6.5 degrees can also be used to make SiNa. In the book Lun Heng, Wang Chong of the Eastern Han Dynasty made a clear record of the shape and usage of Sina. Sina is made of a whole natural magnet after pondering. The handle of the spoon is guided by the pole, so that the center of gravity of the whole spoon falls right in the middle of the bottom of the spoon. The spoon is placed in a smooth field, surrounded by a four-dimensional stem and branches, which synthesize 24 directions. This design was completed through long-term research after the ancients carefully observed many phenomena related to magnetism in nature and accumulated a lot of knowledge and experience. The appearance of Sina is the practical application of people's understanding of the polarity of magnet fingers. However, Sina also has many defects. Natural magnets are hard to find, and they are easy to lose their magnetism when they are impacted and heated during processing. Therefore, Sina's magnetism is relatively weak, and the contact with the site should be very smooth, otherwise it will be difficult to rotate because of too much friction and resistance, and the expected guiding effect will not be achieved. Moreover, Sina has a certain volume and weight, which is inconvenient to carry, which may be the main reason why Sina has not been widely used for a long time.
Sina consists of a bronze disc and a magnetic spoon made of a natural magnet. The bronze disc is engraved with 24 directions, and the magnetic spoon is placed on the central circular surface of the disc. When it is at rest, the tail of the spoon points to the south.
The magnetic poles at both ends of each magnet are different, one is called S pole and the other is called N pole. The earth where we live is also a huge natural magnet, with different magnetic poles in the north and south. The South Pole near the Earth's North Pole and the North Pole near the Earth's South Pole. It is precisely because the geomagnetic poles do not completely coincide with the geographical level that the geomagnetic declination phenomenon appears. As we know, like magnetic poles repel and opposite magnetic poles attract, so no matter where on the earth's surface, take a magnetic needle that can rotate freely, and its N pole will always point to the north and its S pole will always point to the south.
More than 2,000 years ago, during the Spring and Autumn Period and the Warring States Period, China had already made farm tools out of iron. When working people are looking for iron ore, they find a magnet and know that it can absorb iron.
Meng Qian Bi Tan is a book about ancient science and technology in China written by Shen Kuo (1031-1095), which talks about some problems of magnetism and compass. In "A Supplementary Talk with Meng Xi Bitan", he talked about various phenomena produced by the friction magnetization method: "When a magnet is used to rub, it will be sharp and always oriented. Some people will point to the north and are not afraid of stones ... On the contrary, there should be differences between the north and the south, which has not been thoroughly studied." That is to say, after rubbing the sewing needle with a magnet, it sometimes points to the north in a tit-for-tat manner. Magnets have N and S poles, and the direction of sewing needle is different when magnetized, so the direction after magnetization is also different. But Shen Kuo didn't know this truth. He truly recorded this phenomenon and frankly admitted that he didn't think deeply. I hope future generations can explore further. Regarding the installation method of the magnetic needle, Shen Kuo introduced four methods:
1. floating compass-put some wicks on the magnetic needle and float on the water to indicate the direction.
2. Bowl Lip Rotating Compass-Put the magnetic needle on the edge of the bowl, and the magnetic needle can rotate to indicate the direction.
3. nail rotating compass-put the magnetic needle on the nail. Because the nail surface is smooth, the magnetic needle can rotate freely to indicate the direction.
4. Hang a compass-coat some wax in the middle of the magnetic needle, stick a silk on it, and hang it in a windless place to indicate the direction.
5. Bracket compass-use turtle magnet instead of compass. The head compass and tail compass are not much different from hanging compass.
The guide turtle was a popular new device at that time. Place a natural magnet in the abdomen of the wooden turtle, dig a smooth hole under the abdomen of the wooden turtle, align it, and put it on a sharp bamboo nail, which stands upright on the board, so that the wooden turtle is placed on a fixed fulcrum that can rotate freely. Because the friction at the fulcrum is very small, the wooden turtle can rotate the guide rail freely. It was not used for navigation, but for illusion. But this is the predecessor of the drought compass that appeared later.
The guide turtle was invented no later than 1325. The wooden block is carved into the shape of a turtle, and a magnet is embedded in the center of the turtle's abdomen. The wooden turtle was placed on a column with a pointed tip, pointing to the north and south respectively when it was at rest.
In order to determine the direction, in addition to the compass, it is also necessary to have an azimuth disk to cooperate. When you first use a compass, you may not have a fixed azimuth dial. With the need of azimuth measurement, a compass with integrated magnetic needle and azimuth disk appeared. Compasses include feng shui compass, water compass and drought compass.
Twenty-four directions are carved around the disc, which is filled with water. The magnetic needle passed through the rush and floated on the water.
As we all know, the two magnetic poles of the earth are only close to the geographical North Pole and South Pole, but they do not coincide. The magnetic needle points to the magnetic pole of the earth rather than the geographical north and south poles, so the magnetic needle points slightly away from the direction of due south rather than due north. This angle is called magnetic declination. Because the earth is almost spherical, the magnetic needle will tilt downward when it points to the magnetic pole, and there is an angle with the horizontal direction, which is called the magnetic inclination angle. The magnetic declination and inclination are different at different positions. Wu Yao in the Northern Song Dynasty paid attention to the application of magnetic inclination when discussing how to make a compass by geomagnetic method. Shen Kuo talked about an incomplete compass in Meng Qian Bi Tan, which is often slightly to the east. The existence of magnetic declination is pointed out. The discovery of magnetic declination and magnetic inclination makes the compass point more accurately.
During the Wei, Jin, Southern and Northern Dynasties, China ancestors had a lot of knowledge about the nature of magnets. Even Cao Zhi, a poet at that time, used "a magnet attracts iron, but gold is not connected" in Jiao Zhi's poems. Sentence. It can be seen that he also knows the nature of magnets. 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, which are very magnetic and can attract three or four iron needles, so that several needles can be hung on the magnets end to end. Magnets with stronger magnetism can attract more than ten iron needles, and even hold one or two pounds of knives. 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.
Magnets attract iron because the magnetic poles at both ends of each magnet are different, one is called positive pole and the other is called negative pole. The earth where human beings live is also a huge natural magnet. The north pole and south pole of the earth also have different magnetic poles. The north pole of the earth is negative, and the south pole of the earth is positive. According to the principle that like magnetic poles repel and opposite magnetic poles attract, take a magnetic needle that can rotate freely. No matter where you stand on the earth, its positive pole always points to the north, and its negative pole always guides you.
During the Warring States period, people used the characteristics of magnets to make a tool to indicate the north and south-Sina. However, what Sina looked like in the Warring States period is impossible to verify. Illustration of China History Textbook-"Sina" is based on the "Sina Model of Han Dynasty" of China History Museum. This model was made by later generations according to historical records and the physical objects of Han Dynasty sites unearthed underground. The site is made of bronze, with an inner circle and an outer circle, and the central round surface is polished very smoothly to ensure the accuracy of the direction indicated by the spoon body. On the periphery of the central circle, eight diagrams, heavenly stems, earthly branches and twenty-eight lodges are arranged in turn, counting twenty-four directions. The small spoon in the center of the site was ground with a whole natural magnet. The anode of the magnet was ground into a long handle of Sina, and the bottom of the spoon head was hemispherical and very smooth. When using, first put the site flat, then put Sina in the middle of the site, and move the spoon handle by hand to make it rotate. When Sina stopped, the spoon handle pointed in the direction of the south. This spoon-shaped Sina was used until the eighth century.