The important position of the four great inventions in the history of human civilization is one of the signs that China has become an ancient civilization. In ancient times, our country's science and technology used to be at the forefront of the world in many aspects, but the glorious history of the past does not equal the glory of the present. For more than a thousand years after the 5th century, Europe was in a feudal society. During this long period, our country's science and technology has been developing forward, while Europe's science and technology has stagnated. In the fifteenth and sixteenth centuries, due to the disintegration of the feudal system and the gradual formation of the capitalist system, modern natural science in Europe was born, but it advanced by leaps and bounds, surpassing China and leading the world. Since then, China's scientific development has basically been lagging behind that of Western countries. So in the end, Western powers used the compass and gunpowder invented by China to directly attack China. During the Qing Dynasty, China was forced to cede territory and pay compensation, turning China into a semi-colonial and semi-feudal country.
Chinese people all know the four great inventions, so they talk about them with great enthusiasm. However, thousands of years have passed, do the Chinese have any other great inventions worth boasting about? At the same time, there are countless great inventions that have changed human history all over the world. For example: steam engines, electricity, electric lights, computers, cars, airplanes, the Internet, etc. In particular, there are countless great inventions made by Americans and Europeans that have changed the world. Have you seen them being complacent about their own country's great inventions and happily publicizing them everywhere? Are their great inventions equally few and far between, just these four? It is important to understand the glorious history of one's own country, but clinging to the past will lead to stagnation, complacency and self-paralysis. The Chinese people's great inventions should not only be these four, but should continue to increase with the development of history. Therefore, the correct name of the Four Great Inventions should be the Four Great Ancient Inventions.
[Edit this paragraph] Compass
A compass is a simple instrument used to determine direction. Formerly known as Si Nan. The main component is a magnetic needle mounted on a shaft that can rotate freely. The magnetic needle can be kept in the tangent direction of the magnetic meridian under the action of the earth's magnetic field. The north pole of the magnetic needle points to the geographical south pole, and this property can be used to identify directions. Commonly used in navigation, geodesy, travel and military.
The invention of the compass is the result of our country’s working people’s understanding of the magnetism of objects through long-term practice. Due to production labor, people came into contact with magnetite and began to understand the magnetic properties. People first discovered the properties of magnets and magnets. Later, the directivity of magnets was discovered. After many experiments and research, a practical compass was finally invented.
After being introduced to Europe, the compass played an irreplaceable role in the discovery of navigation. But science historians know that the first person to answer the question "Why does the compass guide?" was not the Chinese, but the British scientist Gilbert. So, what kind of discussion did China have on the compass theory after the invention of the compass? Did Gilbert's theory reach China in time? What impact did the "spread of Western learning eastward" in the late Ming and early Qing dynasties have on the development of compass theory in my country? Guan Zengjian, a professor at the Department of History and Philosophy of Science at Shanghai Jiao Tong University, began researching these largely blank issues in 2003.
"China's earliest compass theory is the 'induction theory' based on the theory of yin and yang and the five elements." Guan Zengjian introduced that in the middle of the 11th century, the great Chinese scientist Shen Kuo was still incredible about the compass. His "Dream" "Xi Bi Tan" introduced the artificial magnetization method of the compass, the discovery of magnetic declination and the installation method of the compass, but had no idea why the compass guides - "The guide of the magnet...cannot be understood!" Later, the literati Starting from the theory of yin and yang and the five elements, and combined with people's understanding of the shape of the earth at that time, scholars proposed various compass theories. For example, "Guan's Geography Guide to Meng", which was last written in the Song Dynasty, first put forward the following logic:
"The magnetic needle is made of polished iron, and iron belongs to gold. According to the theory of the five elements, gold generates water. The north belongs to water, so the water in the north is the son of gold. Iron is produced from magnets, and magnets are produced by the yang energy. The yang energy belongs to fire and is located in the south, so the south is equivalent to the mother of magnetic needles. To care for the mother and to cherish the children, it is natural to point in the north and south directions."
Guan Zengjian said that from the perspective of modern physics, the "Montessori theory" is completely whimsical, but it is explained based on the properties of things. This behavior is a common practice in the history of Eastern and Western science. The theory of yin and yang was prosperous in ancient my country. It is only natural to use the theory of yin and yang to explain the compass guide and the principle of "always slightly to the east". In particular, this theory believes that different end faces of magnets have different properties, which determine the direction of the magnetic needle. This statement can easily inspire people to discover the two poles of the magnet, and further associate them with the relationship between the magnetic poles and the direction of the magnetic needle, thereby providing a correct understanding of this problem. Problems find possible paths.
The compass principle of the Southern Song Dynasty people still believed that "the point of the compass is where the Yang Qi is". It only revolved around the phenomenon of magnetic declination, and the basis for the argument turned more to the coordinate system of geographical orientation - ancient Chinese believed The earth is flat and has limited size, so there must be a center on the earth's surface, and the meridian passing through the center is the only north-south direction. Zeng Sanyi and others from the Southern Song Dynasty believed that once the measurement location is not on this north-south line, the compass will naturally point "less biased".
By the Ming Dynasty, some people relied on the writings of the Southern Tang Dynasty to point out that the compass needle was determined by the earth's position system, while the declination was determined by the celestial body's position division system. Guan Zengjian believes that this statement "embodies the embarrassment of traditional compass theory in the face of the contradiction between the yin and yang induction theory and the existence of magnetic declination."
During the Wanli period of the Ming Dynasty (1573-1620 AD), missionaries came to China and brought Western compass theory, earth theory and related scientific and technological knowledge. Affected by this, Chinese scholars began to explore compass theoretical issues from a new perspective. In the process, the role of yin and yang and the five elements continued to fade, and analysis from a mechanical perspective continued to increase. However, the scientific theory proposed by Gilbert in 1600 was not even unified by Western academic circles. , let alone take over the Eastern Land. Among the missionaries, the Belgian Jesuit Nan Huairen who arrived in China in 1658 had the most systematic compass theory. However, he believed that it was the geographical north and south poles of the earth that determined the direction of the magnetic needle. His theory was still limited to the scope of ancient science, unlike Gilles. Burt recognized the existence of a magnet in the Earth itself. Nan Huairen's theory had a profound influence in China. Until the middle of the 19th century, there were still scholars in my country using it to explain compass issues. At this time, missionaries who came to China in the late Qing Dynasty had begun to introduce modern Western magnetism knowledge to China.
In the pre-Qin era, our ancestors have accumulated a lot of knowledge in this regard. When exploring iron ore, they often encountered magnetite, that is, magnet (the main component is ferric oxide). These discoveries were documented very early on. Several chapters of "Guanzi" first recorded these discoveries: "If there is a magnet on the mountain, there is gold and copper underneath." There are similar records in other ancient books such as "The Classic of Mountains and Seas". 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 said: "Charity attracts iron, or it attracts it." People at that time called "magnetism" "ci" and they attracted the magnets. Iron is regarded as the attraction of a loving mother to her children. He also believed: "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." It is said that after Qin Shihuang unified the six countries, he built Afang near Xianyang. There is a door in the palace made of magnets. If someone wears armor and hides weapons and enters the palace to assassinate, he will be attracted by the magnet door. This story tells us that the ancient working people mastered the knowledge of magnetism very early.
Before the Han Dynasty, people wrote magnets as "loving stones", which means loving stones.
Since magnets can attract iron, can they also attract other metals? Our ancestors made many attempts and found that magnets not only cannot attract gold, silver, copper and other metals, but also cannot attract items such as bricks and tiles. During the Western Han Dynasty, people had realized that magnets could only attract iron, but not other items.
When two magnets are placed close to each other, they sometimes attract each other and sometimes repel each other. Now people all know that a magnet has two poles, one is called the N pole and the other is called the S pole. Same-sex poles repel each other, and opposite-sex poles attract each other. People at that time did not know this truth, but they were still aware of this phenomenon.
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 mutual position of the polarity of the two chess pieces, sometimes the two chess pieces moved toward each other. Attract 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". Luan Da took advantage of the properties of magnets and made novel gadgets to deceive Emperor Wu of the Han Dynasty.
The earth is also a large magnet, with its two poles close to the geographical south pole and the geographical north pole respectively. Therefore, when the magnets on the earth's surface can rotate freely, the properties of like magnets repel each other and opposite magnets attract each other indicate north and south. The ancients did not understand this truth well, but they were very aware of this phenomenon.
The ancestor of the compass appeared around the Warring States Period. It is made of natural magnet. It looks like a spoon with a round bottom. It can be placed on a smooth "land" and maintain balance, and it can rotate freely. When it is at rest, the handle of the spoon will point south. The ancients called it "Sinan", and the book "Han Feizi" at that time said: "The king established Sinan to end the day and night." "Duanzhaoxi" means to make the four directions and determine the direction. "Guiguzi" records the use of Si Nan. The people of Zheng took Si Nan with them when picking jade to ensure that they would not lose their way.
During the Spring and Autumn Period, people were able to carve nephrite and jadeite with a hardness of 5 to 7 degrees into utensils of various shapes. Therefore, natural magnets with a hardness of only 5.5 to 6.5 degrees could also be made into sinan. . Wang Chong of the Eastern Han Dynasty made a clear record of the shape and usage of Sinan in his book "Lunheng". Sinan uses a whole piece of natural magnet to make a spoon shape after polishing. The handle of the spoon refers to the pole, and the center of gravity of the entire spoon falls exactly in the middle of the bottom of the spoon. The spoon is placed on a smooth ground, which is square on the outside and round on the inside. There are four dimensions of stems and branches, forming twenty-four directions. This kind of design was completed after long-term research after the ancients carefully observed many phenomena related to magnetism in nature, accumulated a lot of knowledge and experience. The emergence of Sinan is a practical application of people's understanding of the polarity of magnet fingers. However, Sinan also has many shortcomings. Natural magnets are difficult to find and are prone to loss of magnetism due to impact and heat during processing. Therefore, Sinan's magnetism is relatively weak, and its contact with the ground must be very smooth, otherwise it will be difficult to rotate due to excessive rotational frictional resistance, and the expected guiding effect cannot be achieved.
Moreover, Sinan has a certain size and weight and is very inconvenient to carry. This may be the main reason why Sinan has not been widely used for a long time.
Sinan consists of a bronze plate and a magnetic spoon made of natural magnets. The bronze plate is engraved with twenty-four directions. The magnetic spoon is placed on the central circular surface of the plate. When stationary, the tail of the spoon points south.
A compass is made of magnets. Magnets can attract iron and are often called "iron magnets". In ancient times, they were called "charity stones" because they attract iron as soon as it touches it, just like a kind mother attracts her children. Later, people called it "magnet".
Each magnet has different magnetic poles at both ends, one is called the S pole and the other is called the N pole. The earth we live on is also a large natural magnet. It also has different magnetic poles at the north and south ends. The one closest to the north pole of the earth is the S pole, and the one close to the south pole of the earth is the N pole. We know that same-sex magnetic poles repel each other and opposite-sex magnetic poles attract each other. Therefore, no matter where on the surface of the earth, you take a freely rotating magnetic needle, its N pole will always point to the north and its S pole will always point to the south.
Compasses are made using the properties of magnets. So, which country in the world was the first to discover magnets and their properties?
More than 2,000 years ago, during the Spring and Autumn Period and the Warring States Period, our country had already used iron to make farm tools. Working people discovered magnets when they were looking for iron ore and knew that they could attract iron.
There is such a record in the ancient Chinese book "Guanzi": "Those with loving stones on the top have copper and gold on the bottom." "Copper and gold" is a kind of iron ore. The book "Guanzi" was written in the third century BC, which shows that our country knew that magnets can attract iron as early as the third century BC at the latest.
During the Qin Dynasty, there was an interesting legend. After Qin Shihuang unified China, he built a large Afang Palace in Xianyang, Shaanxi. There was a magnet door in the Afang Palace, which was made entirely of magnets. If someone wants to assassinate someone with an iron weapon, as long as he passes there, the magnet door will attract him.
In addition, according to ancient records, during the time of Emperor Wu of the Han Dynasty, there was a Luan Da in Jiaodong who dedicated a chess game to Emperor Wu of the Han Dynasty. Once these chess pieces are placed on the chessboard, they will collide with each other and start fighting automatically. Emperor Wu of the Han Dynasty was very surprised when he saw it. It turns out that the larger chess pieces are made of magnets, so they are magnetic and can attract and collide with each other. It's just that Emperor Wu of the Han Dynasty didn't understand this principle.
In ancient times, thin iron leaves were often cut into fish shapes. The belly of the fish was slightly concave, like a small boat. After being magnetized and floating on the water, it could guide north. It was used as a game at the time. Cui Bao of the Eastern Jin Dynasty mentioned this "guide fish" in "Annotations to Ancient and Modern Times".
During the Northern Song Dynasty, Zeng Gongliang recorded in the "Wu Jing Zong Yao" the method of making and using guide fish: "Cut it with a thin iron leaf, two inches long, five minutes wide, and the head and tail are sharp like a fish. Place it in a charcoal fire, burn it, wait until the fish is red, put the fish head out of the fire with an iron sword, put the tail directly opposite the sub-position, dip it in the water basin, stop it when the last few points are gone, collect it in a secret container when using, and put the water bowl in the water bowl. When placed flat against the wind, the fish floats on the water surface, and its head always faces the noon. "This is an artificial magnetization method that uses the earth's magnetic field to magnetize the iron sheet. That is, place the red-hot iron piece in the direction of the meridian. The molecules inside the red-hot iron sheet are in a relatively active state, causing the iron molecules to align along the direction of the earth's magnetic field to achieve magnetization. This arrangement can be fixed quickly by dipping it in water, while the slightly downward tilt of the fish tail can increase the degree of magnetization. The invention of the artificial magnetization method played a huge role in the application and development of the compass. It was also a major event in the history of the development of magnetism and geomagnetism. Shen Kuo of the Northern Song Dynasty mentioned another method of artificial magnetization in "Mengxi Bi Tan": "The Fang family rubs the needle with a magnet, and it can guide the needle." According to Shen Kuo, technicians at that time used magnets to rub sewing needles. , you can make the needle magnetic. From the current point of view, this is a method that uses the magnetic field of natural magnets to make the arrangement of the magnetic domains inside the steel needle tend to a certain direction, so that the steel needle shows magnetism. This method is simpler than the geomagnetic method, and the magnetization effect is better than the geomagnetic method. The invention of the friction method is not only the earliest in the world, but also creates conditions for the emergence of magnetic pointing devices with practical value.
"Mengxi Bi Tan" is a work about ancient Chinese science and technology written by Shen Kuo (1031-1095). The book talks about some issues about magnetism and compasses. In the supplementary talk of "Mengxi Bi Tan", he talked about various phenomena that occur when magnetizing by friction: "If you rub the needle with a magnet, the sharp point will always point to the guide, and some will point to the north. I am afraid that the stone will not have the same quality..., North and South are opposites, so there should be differences, but I haven't examined it deeply. "This means that after rubbing a sewing needle with a magnet, the tip of the needle sometimes points to the north, and sometimes it points to the north. From the current point of view, magnets have two poles, N and S. When magnetized, the direction of the sewing needle tip is different, and the direction after magnetization will be different. But Shen Kuo did not know this truth. He truly recorded this phenomenon and frankly admitted that he did not think deeply about it. I hope future generations can further explore this.
Regarding the installation method of the magnetic needle, Shen Kuo introduced four methods:
1. Water floatation method - put a few rushes on the magnetic needle and float it on the water to indicate the direction.
2. Bowl lip rotation method - place the magnetic needle on the edge of the bowl, and the magnetic needle can rotate to indicate the direction.
3. Nail rotation method - place the magnetic needle on the fingernail. Because the nail surface is smooth, the magnetic needle can rotate freely and indicate the direction.
4. Thread hanging method - apply some wax to the middle of the magnetic needle, stick a piece of silk, and hang it in a windless place to indicate the direction.
Shen Kuo also compared the four methods. He pointed out that the biggest shortcoming of the water floatation method is that the water surface easily shakes and affects the measurement results. The bowl lip twisting method and the nail twisting method have low friction and are very flexible in rotation, but they are easy to fall off. Shen Kuo highly praised the thread-suspended method, which he believed to be an ideal and practical method. In fact, the four methods pointed out by Shen Kuo have summarized the two major systems of compass devices so far - water needles and dry needles.
Chen Yuanliang of the Southern Song Dynasty introduced the production method of another type of guide fish and guide turtle in "Shi Lin Guang Ji". This kind of guide fish is different from what is recorded in the book "Wu Jing Zong Yao". It is carved into a fish shape from wood and is as big as a finger. A natural magnet is placed in the belly of the wooden fish. The S pole of the magnet points to the fish head, and it is made of wax. After sealing, insert a needle through the fish's mouth to become a guide fish. Float it on the water with a fish head guide, which is also a type of water needle.
The Guide Turtle was a popular new device at the time. A natural magnet was placed inside the abdomen of a wood-carved turtle, a small smooth hole was dug under the abdomen of the wooden turtle, aligned and placed upright on a wooden board. The top of the wooden turtle is placed on a fixed bamboo nail that can rotate freely. Because there is very little friction at the fulcrum, the wooden turtle can rotate the guide freely. At that time it was not used for navigation, but for illusion. But this was the precursor to the dry compass that would later appear.
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 is placed on a pointed vertical support. When it is at rest, the head and tail point to the north and south.
In addition to the compass, you also need an azimuth disk to determine the direction. When the compass was first used, there may not be a fixed azimuth disk. With the need to measure the direction, a compass with a magnetic needle and an azimuth disk integrated appeared. The compass includes a compass, a water compass, and a dry compass.
The azimuth disk is still 24-way, but the disk shape has evolved from square to circular. In this way, you can determine the direction just by looking at the position of the magnetic needle on the azimuth disk. During the Southern Song Dynasty, Zeng Sanyi recorded relevant literature in this regard in "Yin Hua Lu": "The earth snail may have a Ziwu Zheng needle, or a Ziwu Bingren needle." This is the earliest documented record of the compass disk. The "earth snail" mentioned in the literature is the earth snail, which is also the compass disk. Knowledge of magnetic declination has been applied to compasses in the literature. This kind of compass not only has a meridian needle (the magnetic needle that determines the direction of the north and south poles of the earth's magnetic field), but also a meridian needle (the direction of the geographical north and south poles determined by the shadow of the sun). The angle between these two directions is the magnetic deflection. horn.
Twenty-four directions are carved around the disk, with water inside, and a magnetic needle crossing the lamp grass and floating on the water.
People now know that the two magnetic poles of the earth are close to the geographical north and south poles, but do not coincide with each other. The magnetic needle points to the earth's magnetic poles instead of the geographical north and south poles. In this way, the magnetic needle does not point in the direction of true south or true north but is slightly deviated. This angle is called magnetic declination. And because the earth is approximately spherical, the magnetic needle must tilt downward when it points to the magnetic pole, and there is an angle with the horizontal direction. This angle is called the magnetic inclination angle. Magnetic declination and magnetic inclination are different in different locations. The "Wu Jing Zong Yao" written in the Northern Song Dynasty paid attention to the use of magnetic inclination when talking about using geomagnetic method to make compasses. Shen Kuo said in "Mengxi Bi Tan" that the compass is not a complete guide and often deviates slightly to the east. The existence of magnetic declination is pointed out. The discovery of magnetic declination and magnetic inclination made the compass point more accurate.
Once the compass was invented, it was quickly used in military, production, daily life, topographic survey and other aspects, especially in navigation. The application of compass in navigation has a gradual development process. "Pingzhou Ke Tan", which was written slightly later than "Meng Xi Bi Tan", records: "The boat master knows geography, observes the stars at night, observes the sun during the day, and observes the compass in the dark." This is the earliest in the history of world navigation. Records of using a compass. The article points out that at that time, the compass was only used when the sun, moon and stars could not be seen. It can be seen that when the compass was first used, the user was not yet skilled in using it. More than twenty years later, Xu Jing's "The Illustrated Book of Xuanhe's Envoys to Korea" also had a similar record: "Only look at the stars moving forward, and if it is dark, use a compass needle to guide the north and south." By the Yuan Dynasty, the compass jumped It has become the most important instrument for navigation at sea. No matter it was sunny or cloudy, I used the compass to navigate. It also compiled a diagram of the compass needle positions at different navigation locations using compass navigation, which is called a "needle path." When the ship sails to a certain place, the needle position and direction are clearly marked along the way, which serves as the basis for navigation.
The invention of the compass is the result of ancient ancestors’ observation and research on magnetic phenomena. In the process of observing and studying magnetic phenomena, ancient ancestors further understood the properties of magnetism and tried to apply these properties more. Legend has it that when Qin Shihuang built the Epang Palace, one of the palace doors was made of magnets. If an assassin passes by with a sword, he will be immediately sucked in and captured by the guards on the spot. There are many such stories. "Book of Jin. Biography of Malong" records that Malong led his troops westward into Gansu and Shaanxi areas and piled magnets on both sides of the narrow road that the enemy must pass through. When the enemy soldiers wearing iron armor passed by, they were firmly sucked and unable to move. Malon's soldiers wore rhinoceros armor, so magnets had no effect on them and they could move freely. The enemy thought they were magic weapons and retreated without fighting.
The "Foreign Object Chronicle" of the Eastern Han Dynasty records that there are some reefs and shoals around the South China Sea islands that contain magnets. The magnets often attract ships "enclosed with iron leaves", making it difficult to escape.