1. The compass is a simple instrument for judging the orientation. Formerly known as Sina. The main component is a magnetic needle which 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 north pole, and this property can be used to distinguish the direction. It is often used in navigation, geodesy, travel and military affairs. N of the compass refers to the north, e to the east, w to the west and s to the south.

2. Papermaking is one of the four great inventions in China and an outstanding invention in the history of human civilization. China is the first country in the world to raise silkworms and weave silk. In ancient China, the working people spun silk from the superior cocoons, and the rest of the evil cocoons and diseased cocoons were made of silk floss by bleaching. After floating, some residual flocs will be left on the mat.

when the number of flossing is increased, the residual flossing on the mat will accumulate into a fiber sheet, which can be peeled off after drying and can be used for writing. The number of by-products of this kind of floe is small, and it is called "Heqi" or "Square Flock" in ancient books. This shows that the origin of China's papermaking is related to silk wadding.

3. Gunpowder

A kind of black or brown explosive, which is made of potassium nitrate, charcoal and sulfur by mechanical mixing, was initially made into powder, and then generally made into granules of different sizes for different purposes. Before smokeless gunpowder was adopted, it was always used as the only military propellant.

gunpowder was invented by an ancient alchemist in China during the Sui and Tang Dynasties, and it has been more than a thousand years since. The study of gunpowder began with the ancient Taoist alchemy. The ancients refined Dan medicine in order to live forever. The purpose and motivation of alchemy were advanced, but its experimental method still had some merits, which finally led to the invention of gunpowder.

4. Printing

(1) Block printing:

At present, the earliest block printing product is a one-page version of the Darani Sutra written in Indian Sanskrit, which was printed on linen paper and published between 65 and 67, and was unearthed in the Tang Dynasty mausoleum near Xi 'an in 1974.

In p>1966, archaeologists discovered a miniature Darani Buddhist Sutra in South Korea, which contained the script of Zetian written by Empress Wu Zetian of the Tang Dynasty (about 69 -75). Scholars concluded that the sutra was not earlier than 74, and was later treasured in a stupa built in 751 in the era of unified Silla.

(2) woodblock printing:

According to the research of historian Deng Guangming, woodblock printing was invented in the Tang Dynasty, which was the most developed golden age in the history of China. Many Taoist priests participated in the research and innovation of printing, and it was widely used in the middle and late Tang Dynasty. ? Although movable type printing was invented in Song Dynasty, block printing was still widely used.

(3) Movable type printing:

Shen Kuo, a scientist, politician and Taoist scholar in the Northern Song Dynasty, once wrote an article in Mengxi Bi Tan, which introduced the whole process of movable type printing in detail, which was easy to understand and very detailed.

In his 188 book "A Talk on Mengxi", he attributed this invention to an unknown craftsman Bi Sheng (99 -151). With the use of sintered clay characters, Shen Kuo described that Bi Sheng made glyphs, arranged the characters, printed them, and disassembled them after printing for later use. Although movable type printing was invented in Song Dynasty, block printing was still widely used.

(4) Wooden movable type:

In Yuan Dynasty, Wang Zhen, a famous Taoist scholar, agronomist and mechanic, invented wooden movable type and created a relatively simple turntable typesetting method suitable for the complex characteristics of Chinese characters; Later, metal movable type was invented, which improved movable type printing. The printed engraving of the Tang Dynasty spread to Japan. In the late 8th century, Japan completed the Darani Classic, and then spread to Korea, the Middle East and Eastern Europe. In the 15th century, Germans learned to cast characters with alloys, and movable type printing, which was first created in Bi Sheng, spread all over Europe.

Extended information:

The Chinese nation has always been proud of the "four great inventions"-papermaking, printing, gunpowder and compass. However, the term "four great inventions" was born during the Anti-Japanese War.

Chinese civilization has many names related to the "Four Classics", such as the Four Books and Five Classics, Four Beautiful Women, Four Calligraphers in the Early Tang Dynasty, Four Outstanding Calligraphers in the Early Tang Dynasty, Yuan Sijia, Four Wonderful Books, Four Classical Novels, etc. Although the "Four Great Inventions" is also one of them, this name is much younger than the above, and even more unexpectedly, it was first put forward by a foreigner.

at first, the "three great inventions" were put forward by Francis Bacon, a British philosopher in the 17th century. Bacon thinks that the three inventions of printing, gunpowder and compass have changed the whole face and situation of things all over the world: the first is in academics, the second is in war, and the third is in navigation.

And it has caused countless changes. No sect, no empire or any star has more influence on human affairs than these mechanical discoveries. ". Bacon's statement was recognized by British sinologist Maddox and revolutionary mentor Marx.

maddox pointed out: "China people's invention talent has been manifested in many aspects for a long time. The three great inventions of China people have provided extraordinary impetus to the development of European civilization. " Marx made such a comment: "gunpowder, compass and printing-these are the three great inventions that predicted the arrival of bourgeois society."

gunpowder blew the chivalry to pieces, 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 for spiritual development. "

The first person to add papermaking to the above three inventions was Yue Se, a missionary and sinologist who came to China. When comparing Japan and China, he pointed out that "we must always remember that they (referring to Japan) have no outstanding inventions like printing, papermaking, compass and gunpowder ..." This list of inventions was later carried forward by Joseph Needham, a famous British historian of science and technology.

In p>1942, War of Resistance against Japanese Aggression was in a stalemate. Although the guerrillas behind the enemy lines led by the * * * production party were flourishing, the Kuomintang army was defeated and demoralized, and Chiang Kai-shek was worried and restless. In the face of the Republic of China, where mountains and rivers are broken and lives are ruined, Chiang Kai-shek felt that it was urgent to use something to cheer up the morale of the army and inspire the people.

At this time, he happened to hear that Joseph Needham, a British scholar, was engaged in the history of science and technology in China, so he immediately sent someone to take Joseph Needham and his assistant, lu gwei-djen, his wife in China, to Chongqing, and let him study the history of science and technology in China. What Chiang Kai-shek talked to Joseph Needham when he met him is unknown to outsiders.

But what we know is that Joseph Needham soon put forward in Chongqing the following year, that is, in 1943, that papermaking, printing, compass and gunpowder were the "four great inventions" in ancient China, and this research result caused a sensation in China and then spread all over the world.

Baidu Encyclopedia-Four Great Inventions in China