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China’s Four Great Inventions

Compass

Before the invention of the compass, human beings often lost their way when sailing in the vast sea, causing unimaginable consequences. It was the Chinese who invented the compass, which gave human beings navigation a direction. . The compass is a simple instrument used to determine direction. One of the four great inventions in ancient China. 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 the long-term understanding of the magnetism of objects by the working people of our country. 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.

The discovery of magnetic phenomena

In the pre-Qin era, our ancestors have accumulated a lot of knowledge in this area. When exploring iron ore, they often encountered magnetite, that is, magnetite (the main component It is ferric oxide). These discoveries were documented very early on. Several chapters of "Guanzi" first record 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 says: "Charity attracts iron, or 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 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."

Before the Han Dynasty, people wrote about magnets. To be a "loving stone" means a loving stone.

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 - Sinan

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.

In the Spring and Autumn Period, people have been 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 can 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. 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 is composed 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.

The invention of the compass

In ancient times, thin iron leaves were often cut into the shape of a fish. The belly of the fish was slightly concave, like a small boat. After being magnetized and floating on the water, it could guide the 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".

In the Northern Song Dynasty, Zeng Gongliang recorded the method of making and using guide fish in "Wu Jing Zong Yao": "Cut it with a thin iron leaf, two inches long, five minutes wide, and the head and tail are sharp like a fish. Put it in the charcoal fire, wait until it is red, put the fish head out of the fire with an iron sword, with the tail facing the subposition, dip it in the water basin, stop it when the last few points are gone, collect it with a tight container, and put the water bowl in the empty bowl. When placed flat in 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 piece. 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.

Shen Kuo also talked about the various phenomena that occur when magnetizing by friction in the supplementary talk of "Mengxi Bi Tan": "If you rub the needle with a magnet, the sharp point will always be a guide, and some will point to the north. The nature of fear of stones is not the same... North and South are opposite, so there should be differences, but I haven't studied 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.

As for how to install 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. Since the nail surface is smooth, the magnetic needle can rotate freely and indicate the direction.

4. Wire 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.

"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.

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 new device that was popular 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.

Compass positioning

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 documents in this aspect in "Yin Hua Lu": "The earth snails may have Ziwu Zhengzhen needles, or use Ziwu Bingrenjian needles." 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.

Now people 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 the 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.

Application of magnetic properties

Once the compass was invented, it was quickly applied to military, production, daily life, topographic survey and other aspects, especially 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 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 were not visible. It can be seen that when the compass was first used, the user was not yet skilled in using it. More than 20 years later, Xu Jing's "Xuanhe Envoy to Korea Illustrated Book" also had a similar record: "Just look at the stars moving forward, and if it is dark, use a compass to guide the north and south.

"In the Yuan Dynasty, the compass suddenly became the most important instrument for navigation at sea. It was used for navigation regardless of day or night. Compass navigation was also compiled to show the connection diagrams of compass needle positions at different navigation locations. It is called the "needle path". When the ship goes somewhere, the direction of the needle is clearly marked along the way.

The invention of the compass is the observation and analysis of magnetic phenomena by ancient ancestors. The results of the research. In the process of observing and studying magnetic phenomena, ancient ancestors further understood the properties of magnetism and tried to apply these properties more. It is said that when Qin Shihuang built the Afang Palace, one of the palace doors was made of magnets. If an assassin passes by with a sword, he will be immediately sucked and captured on the spot by the guards. There are many such stories. "Book of Jin. The Biography of Malong" records that Malong led his troops westward to the Gansu and Shaanxi areas, and the enemy must pass through the narrow area. Magnets were piled on both sides of the road. When the enemy soldiers wearing iron armor passed by, they were firmly sucked and unable to move. Malong's soldiers wore rhinoceros armor, so the magnets had no effect on them and they could move freely. They thought they were magic soldiers and could not fight. And retreat. The "Foreign Objects" 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 by iron leaves", making it difficult to escape.

During the Wei, Jin, Southern and Northern Dynasties, our ancestors had a lot of understanding of the properties of magnets. Even the poet Cao Zhi at that time used the phrase "magnets attract iron, and they are not connected to gold." " sentence. It can be seen that he also understood the properties of magnets. Tao Hongjing of the Liang Dynasty in the Northern and Southern Dynasties proposed the method of magnetic measurement in "Famous Doctors". He pointed out: Excellent magnets are produced in the south. They have strong magnetism and can attract three or four roots. Iron needles are connected end to end on the magnet. A magnet with stronger magnetism can attract more than ten iron needles, and can even absorb one or two pounds of knives. Tao Hongjing not only proposed that there are strong and weak magnets. And pointed out the measurement method. This may be the earliest record of magnetic measurement in the world.

The research and understanding of the properties of magnets by our ancestors is the basis for the invention and development of the compass. >China invented two methods of artificial magnetization during the Northern Song Dynasty: one is the method of rubbing steel needles with natural magnets as mentioned by Shen Kuo, and the other is to use the effect of the earth's magnetic field to magnetize steel.

People pass a magnetized steel needle through a few lamp grasses and put it in a bowl filled with water. It can float on the water and point the direction of the ship. This is the world's earliest instrument used to point the direction - the compass. . And many animals have learned to use the earth's magnetic field to identify directions before us.

Gunpowder

Gunpowder is one of the four great inventions of ancient my country because it uses saltpeter, sulfur and It was made from a mixture of three substances: charcoal. At that time, people used these three things as medicine to treat diseases, so it was named "gunpowder", which means "fire medicine".

Since the Qin and Han Dynasties. The alchemy family used sulfur, saltpeter and other substances to make elixirs. They got inspiration from the phenomenon of accidental explosions, and after many practices, they found the formula of gunpowder. During the Three Kingdoms period, there was a clever technician Ma Jun who made gunpowder by wrapping it in paper. Invented "firecrackers" for entertainment and pioneered the use of gunpowder.

In the late Tang Dynasty, gunpowder began to be used in military applications. Throwing it out to burn the enemy is the most primitive form of artillery. Later, people wrapped the spherical gunpowder near the arrow shaft head, lit the fuse, and then shot the gunpowder out with the bow and arrow to burn the enemy. Some bitumen, tung oil, etc. were pounded together to make poison balls. After being lit, they were shot with bows and arrows to kill the enemy. In the Song Dynasty, people filled the gunpowder in bamboo tubes with small sticks on the back. The "directional rod" ignited the gunpowder on the fire tube, causing the gunpowder in the tube to burn rapidly, generating forward thrust, causing it to fly towards the enemy's position and explode. This was the world's first gunpowder rocket. Later, the musket was invented. Guns and guns, these are primitive tubular firearms made of bamboo tubes, are the ancestors of modern guns.

Papermaking

The invention of papermaking technology is the Chinese nation's innovation. One of the contributions to world civilization.

About 3,500 years ago during the Shang Dynasty, my country had characters carved on tortoise shells and animal bones, called oracle bone inscriptions.

In the Spring and Autumn Period, bamboo and wood chips were used to replace tortoise shells and animal bones, which were called bamboo slips and wooden slips. Oracle bones and slips are both heavy and heavy. During the Warring States Period, when the thinker Hui Shi went out to give lectures, he took five carts of slips with him, so there is an allusion to the saying that he learned to be rich in five carts. In the Western Han Dynasty, the court nobles also used silk or tissue paper to write. Silk is a general term for fine silk and silk fabrics. When writing on silk, silk is easy to write on. Not only can you write more than bamboo slips, but you can also draw on it. However, it is expensive and can only be used by a few royal nobles. Paper already existed in the early Western Han Dynasty in the 2nd century BC.

Inventor

In the first year of Yuanxing (AD 105), Emperor He of the Eastern Han Dynasty, Cai Lun invented the silk fabric made of bark and silk based on the experience of his predecessors. Broken fishing nets, rags, hemp heads, etc. were used as raw materials to make plant fiber paper suitable for writing, making paper a commonly used writing material. It is called "Cai Hou Paper".

Cai Lun only improved papermaking, not the inventor of paper.

Papermaking was introduced to Japan via Korea in the 7th century. It spread to the United Arab Emirates in the mid-8th century. It was not until the 12th century that Europe followed China's example and began to set up factories to make paper.

Place of invention

Luoyang

Printing

Printing is one of the four great inventions in ancient China. It began with block printing in the Sui Dynasty, and was developed and perfected by Bi Sheng during the reign of Emperor Renzong of the Song Dynasty. Movable type printing was produced and spread to Europe by the Mongols, so later generations called Bi Sheng the ancestor of printing. Chinese printing is the forerunner of modern human civilization, creating conditions for the widespread dissemination and exchange of knowledge.

Block printing is to use a knife to carve protruding reverse writing on a piece of wood, and then add ink and print it on the paper. Every time a new book is printed, the board has to be carved from scratch, which is very slow. If there is an error in engraving, you have to start over again, and you can imagine the hard work.

Between 1004 and 1048 AD, Bi Sheng, an engraving worker in the Northern Song Dynasty, used fine and sticky clay to make long square cylinders, and carved single characters written in reverse on them. One character and one seal were placed in an earthen kiln and hardened with fire to form movable type. Then according to the content of the article, the words are arranged in order, placed on iron frames to make printing plates, and then heated and flattened on the fire, and then it can be printed. After printing, remove the movable type so it can be reused next time.

Although this printing method is primitive and simple, it has the same principle as modern typesetting, bringing printing technology into a new era.

Later, Wang Zhen, a famous agriculturist and mechanist in the Yuan Dynasty, invented wooden movable type and created a relatively simple rotary typesetting method suitable for the complex characteristics of Chinese characters. Later, he invented metal movable type, making movable type more popular. Printing has been improved. The engraved seals of the Tang Dynasty were spread to Japan. In the late 8th century, Japan completed the wooden board "Dharani Sutra" and then spread to the Democratic People's Republic of Korea, the United Arab Emirates and Eastern Europe. In the 15th century, the Germans learned to use alloys to cast stars. Since then, Bi Sheng's pioneering movable type printing has spread throughout Europe.