The steam engine is a reciprocating power machine, which converts the energy of steam into mechanical work. The appearance of the steam engine caused the industrial revolution in the18th century. Until the beginning of the 20th century, it was still the most important prime mover in the world, and then it gradually gave way to internal combustion engines and steam turbines.
From the end of 16 to the end of 17, the British mining industry, especially coal mines, has developed to a considerable scale, and it is difficult to meet the requirements of pumping groundwater only by manpower and animal power, and there are abundant and cheap coal as fuel on site. The needs of reality have prompted many people in Britain, such as Papan, savery and newcomen, to devote themselves to the exploration and experiment of "lifting water by firepower".
The world's first practical steam pump made in savery won the British patent named "Friends of Miners" on 1698. He first filled an egg-shaped container with steam, then closed the steam inlet valve and sprayed cold water outside the container to condense the steam in the container to form a vacuum. Open the water inlet valve, and the water at the bottom of the mine is sucked into the container through the water inlet pipe under the action of atmospheric pressure; Close the water inlet valve, reopen the steam inlet valve, and use steam pressure to press the water in the container out through the drain valve. When the water in the container is drained and filled with steam, close the steam inlet valve and drain valve, and spray water again to condense the steam. In this way, the two egg-shaped containers work alternately and can continuously drain water.
The pumps in savery rely on vacuum suction to pump water, and the pumping depth cannot exceed six meters. In order to pump water from a mine tens of meters deep, it is necessary to install a water pump in the depth of the mine and use high steam pressure to pump water to the ground, which is undoubtedly difficult and dangerous at that time.
Newcomen and his assistant Cali invented the atmospheric steam engine in 1705 to drive the independent water pump, which is called the newcomen atmospheric steam engine. This kind of steam engine was first popularized in Britain, then in continental Europe, and its modified products were still being manufactured until the beginning of19th century. The thermal efficiency of newcomen atmospheric steam engine is very low, which is mainly due to the fact that after steam enters the cylinder, it condenses on the cylinder wall that has just been cooled by water and loses a lot of heat. It is only promoted in coal-producing areas with low coal prices.
1764, British instrument repairman james watt noticed this shortcoming when repairing newcomen steam engine model for Glasgow University, and invented a steam engine with condenser separated from cylinder wall in 1765, and obtained a British patent in 1769. In the early days, Watt's steam engine still used the balance bar and pull rod mechanism to drive the water pump. In order to remove the condensate and air from the condenser, Watt installed an air pump. He also installed an interlayer on the outer wall of the cylinder and heated the cylinder wall with steam to reduce condensation loss.
1782 or so, Watt further improved the machine and completed two important inventions: in the middle of the active cold working stroke, the steam inlet valve was closed to make the steam expand to do work and improve the thermal efficiency; Make the steam do work on both sides of the piston (double-acting) to improve the output power. At this time, the piston has to pull down the lever and push up the lever, and the fan-shaped balance bar and zipper are no longer applicable, so Watt invented the parallelogram mechanism. Watt also applied crank-connecting rod mechanism to steam engine at the end of 18.
Watt's creative work made the steam engine develop rapidly. He turned the machine that can only carry water into a widely used steam engine, which doubled the thermal efficiency and greatly reduced the coal consumption. Therefore, Watt is a reformer of steam engine.
/kloc-Since the late 8th century, steam engines have been widely used not only in mining, but also in smelting, textile, machinery manufacturing and other industries. It has increased the textile output in Britain by five times (from 1766 to 1789) in more than 20 years, provided a large number of consumer goods for the market, accelerated the accumulation of funds and put forward urgent requirements for the transportation industry.
The experiment of using steam engine as propulsion power on ships began in 1776. After continuous improvement, Fulton, USA made the first practical open-wheel propulsion steam engine ship "clermont". Since then, steam engines have been used as propulsion power on ships for more than one hundred years.
180 1 year, Trevithick of England put forward the concept of movable steam engine. 1803, this kind of movable steam engine using railway tracks first appeared in coal mining area, which is the prototype of locomotive. Stephenson of Britain continuously improved the locomotive, and made the "rocket" steam locomotive in 1829. The locomotive is towing a carriage with 30 passengers at a speed of 46 km/h, which has attracted the attention of all countries and created the railway era.
At the end of 19, with the rise of electric power application, steam engines were once used as the main power machinery of power stations. /kloc-in 0/900, there was a steam engine power station with a single unit power of 5 MW in new york, USA.
The development of steam engines reached its peak in the early 20th century. It has the advantages of constant torque, variable speed, reversibility, reliable operation and convenient manufacture and maintenance, so it was widely used in power stations, factories, locomotives, ships and other fields, especially in warships, and became the only prime Mover at that time.
Steam engines can be divided into single-acting and double-acting types according to the fact that steam works on one or both sides of the piston; According to the arrangement of cylinders, it can be divided into vertical and horizontal; According to whether steam expands in one cylinder or continuously in multiple cylinders, it can be divided into single expansion type and multiple expansion type; According to the flow direction of steam in the cylinder, it can be divided into reflux type and single flow type; According to the exhaust mode and exhaust pressure, it can be divided into condensation type, atmospheric type and back pressure type.
The simple steam engine is mainly composed of cylinder, base, piston, crank-connecting rod mechanism, slide valve steam distribution mechanism, speed regulating mechanism and flywheel. The cylinder and base are static parts. The new steam from the boiler enters the slide valve chamber through the main steam valve and throttle valve, and is controlled by the slide valve to alternately enter the left or right side of the cylinder to push the piston to move.
The development of steam engine is first reflected in the improvement of power and efficiency, which mainly depends on the improvement of steam parameters. At the beginning of the steam engine, the steam pressure was only 0.11~ 0.13mpa, and1reached 0.35 ~ 0.7 MPa at the beginning of the 9th century. 10 MPa in the 1920s. In terms of steam temperature, 19 did not exceed 250℃ at the end of the year, but it was used at 450 ~ 480℃ in the 1930s.
As for the efficiency, the total efficiency of the steam engine running continuously in the initial stage of Watt is less than 3% according to the calorific value of fuel; By 1840, the total efficiency of the best condensing steam engine can reach 8%; By the 20th century, the highest efficiency of steam engines can reach more than 20%.
In terms of rotational speed, at the end of 18, Watt steam engine only had 40 ~ 50 revolutions; At the beginning of the 20th century, the speed reached 100 ~ 300 rpm, and some steam engines once reached 2500 rpm. In terms of power, the power of a single machine was only a few horsepower at first, and the power of a marine steam engine at the beginning of the 20th century could reach 25,000 horsepower.
With the improvement of steam parameters and power, steam can not continue to expand in one cylinder, but must continue to expand in the connected cylinder, so there is a multi-stage expansion steam engine. Due to the limitation of the flash point of lubricating oil, the maximum temperature of steam used in steam engines is generally lower than 400℃, and mobile steam engines such as locomotives and ships are slightly lower, most of which are not higher than 350℃. Considering the possibility of expansion and the economy of the structure, the common pressure is below 2.5 MPa. The limited steam parameters also limit the further improvement of steam engine power.
The appearance and improvement of the steam engine promoted the social and economic development, but at the same time, the economic development in turn put forward higher requirements for the steam engine, such as high power, high efficiency, light weight and small size. Although people have made many improvements to the steam engine, expanding the scope of use and improving the performance, with the development of steam turbines and internal combustion engines, the steam engine has gradually declined because of its insurmountable weaknesses.
The weaknesses of the steam engine are: the boiler is indispensable, and the whole device is bulky; The pressure and temperature of fresh steam should not be too high, and the exhaust pressure should not be too low, so it is difficult to improve the thermal efficiency; It is a reciprocating machine, and the inertia force limits the increase of rotation speed; The working process is discontinuous and the steam flow is limited, which limits the promotion of power.
Therefore, the internal combustion engine, which abandoned the heavy boiler, gradually replaced the steam engine on ships and locomotives with its advantages of light weight, small volume, high thermal efficiency and flexible operation. The steam turbine has the advantages of high thermal efficiency, high single machine power, high rotating speed, light weight per unit power and stable operation, so the steam engine is pushed out of the power station.
Then the motor replaced the application of steam engine in industrial equipment because of its convenient use. The thermal efficiency of low-power steam engines is higher than that of steam turbines, so there is still room for steam engines to play a role in coal-producing areas or areas with only inferior fuels, or in some special occasions.
The steam engine has a great historical role, which has promoted the development of machinery industry and even society. The thermodynamics and mechanism established with its development laid the foundation for the development of steam turbines and internal combustion engines. Steam turbine inherits the characteristics of steam engine using steam as working medium, adopts condenser to reduce exhaust pressure, and abandons the shortcomings of reciprocating motion and intermittent steam intake; The internal combustion engine inherits the basic structure and transmission form of the steam engine, and forms a thermal cycle with much higher thermal efficiency by directly inputting fuel into the cylinder for combustion. At the same time, cylinders, pistons, flywheels, flying hammer governors, valves and seals used in steam engines are the basic components of many modern machines.
hybrid rice
Two rice varieties with certain genetic differences and complementary excellent characters are selected to cross to produce a hybrid with heterosis, that is, hybrid rice.
Heterosis is a common phenomenon in biology, and using heterosis to improve crop yield and quality is one of the main achievements of modern agricultural science.
radium (Ra)
A chemical element. Chemical symbol Ra, atomic number 88, atomic weight 226.0254, belongs to IIA group in the periodic table, is a member of alkaline earth metal and a natural radioactive element. 1898 m. Curie and p. Curie separated radium bromide from the slag after extracting uranium from pitchblende, and 19 10 made metal radium by electrolysis of radium chloride. Its English name comes from the Latin radius, which means "ray". The content of radium in the crust is 1× 10-9%. It has been found that isotopes with mass numbers of 206 ~ 230 are all artificially synthesized except for radium 223, radium 224, radium 226 and radium 228, which are natural radioactive isotopes. Radium exists in all uranium mines, and every 2.8 tons of uranium contains 1 gram of radium.
Radium is a silvery white metal with a melting point of 700℃, a boiling point lower than 1 140℃ and a density of about 5g/cm3. Radium is the most active alkaline earth metal, which reacts rapidly with nitrogen and oxygen in air to form nitrides and oxides, and reacts violently with water to form radium hydroxide and hydrogen. The outermost electron shell of radium has two electrons, and the oxidation state is +2, and only +2 valence compounds are formed. Radium salts and corresponding barium salts are isomorphic compounds with similar chemical properties. Radium chloride, radium bromide and radium nitrate are all soluble in water, while radium sulfate, radium carbonate and radium chromate are insoluble in water. Radium is highly toxic and can be concentrated in bones instead of calcium in human body. Acute poisoning can cause bone marrow damage and serious damage to hematopoietic tissue, while chronic poisoning can cause osteoma and leukemia. Radium is a by-product of uranium production. When leaching uranium from uranium ore with sulfuric acid, radium exists in slag in the form of sulfate, and then it is converted into radium chloride. Pure radium salt can be obtained by fractional crystallization with barium salt as carrier. Metal radium is made from electrolytic radium chloride. Radium and its decay products emit gamma rays, which can destroy malignant tissues in the human body, so radium needles can cure cancer.
Element Name: Radium
Atomic weight of element: [226]
Element type: metal
Discovers: Marie Curie and pierre curie: 1898.
Discovery process:
1898 was discovered by Marie Curie and pierre curie. 19 10, Madame Curie and Debin electrolyzed pure radium chloride solution, used mercury as cathode to obtain radium amalgam, and then distilled off mercury to obtain metal radium.
Element description:
The density is 6.0g/cm3 (20℃). The melting point is 700℃ and the boiling point is about 1 140℃. Silvery white smooth soft metal. It is unstable in air, easy to combine with nitrogen and easy to oxidize in air. It reacts with water to release hydrogen and generate radium hydroxide Ra(OH)2. Soluble in dilute acid. Chemical properties are very similar to barium; All radium salts are isomorphic to the corresponding barium salts. Radium can generate sulfate, carbonate, chromate and iodate which are only slightly soluble in water; Chlorides, bromides and hydroxides of radium are soluble in water. Radium is known to have 13 isotope, and 226Ra has the longest half-life of 1622 years.
Element source:
It exists in many kinds of ores and mineral springs, but its content is extremely rare, and more of it comes from pitchblende. When uranium is extracted from pitchblende, radium is usually recovered and purified together with barium in the form of sulfate in acid-insoluble residue.
Element usage:
Radium can emit alpha and gamma rays and produce radioactive gas radon. Radium can destroy and kill cells and bacteria. Therefore, it is often used to treat cancer. In addition, the mixed preparation of radium salt and beryllium powder can be used as neutron radiation source to detect petroleum resources and rock composition.
Element auxiliary data:
Shortly after the discovery of polonium, the Curies had another amazing result. After they separated bismuth compounds rich in polonium from uranium mines, they also separated barium compounds with strong radioactivity. They believe that this mineral also contains a second unknown radioactive element, which was separated from barium at the same time. Their collaborator Belmont successfully studied this unknown radioactive element. 1898 In February, the Paris Academy of Sciences published a report on their cooperation with Beaumont: "... The above reasons make us believe that this new radioactive substance contains a new element, and we suggest calling it radium. ……"
Radium, the Latin name of radium, comes from the Latin word "radius", and its element symbol is defined as ra.
The content of radium in pitchblende is very small, but it is only one in ten million or three in ten million. To separate it, a lot of pitchblende is needed. From 1898 to 1902, a huge amount (one ton) of slag was painstakingly analyzed in a simple laboratory, and finally 0. 1g of metal radium was extracted from 1902, and its atomic weight was preliminarily determined.
The discovery of radium
After Becker's pioneering observation and research on the radioactivity of uranium, he found that uranium rays, like X rays, can make air and other gases conduct electricity, and thorium compounds were also found to have similar properties.
Starting from 1896, Madame Curie and her husband made a systematic discovery, looking for this effect in various elements and their compounds and natural objects.
Mabya Sklodowska Ya, the famous Madame Curie, was born in a scholarly family in Warsaw, Poland on17. My father is everyone's physics professor and my mother is a pianist. Maria, with her father's wisdom and mother's dexterity, has been interested in scientific experiments since she was a child.
189 1 year, she went to Paris to study. After finishing her studies, she originally planned to return to her motherland, which was ravaged by the czar, to make a modest contribution to the motherland, and to do her daughter's filial piety for her parents.
However, the acquaintance, love and lifelong companionship with French physicist Mr. pierre curie completely changed her original plan, so she had to live in France and gave birth to a lovely daughter on 1897.
Becquerel phenomenon aroused the strong interest of Curie and his wife. Where does the power of ray release come from? What is the nature of this radiation?
Madame Curie devoted herself to the study of uranium salts. She collects and studies all kinds of uranium salts and ores extensively. She was attracted by the magical light of uranium salt ore, and she devoted special love to this special ore.
Madame Curie, who received a strict and systematic higher chemistry education, thought that there was no reason to prove that uranium was the only chemical element that could emit radiation when studying uranium salt ores. She guessed that there must be other elements with the same power, but people just didn't know it yet.
She determined the elements one by one according to Mendeleev's periodic law of elements. As a result, she soon discovered another thorium compound, which also automatically emits rays, similar to uranium rays and close in intensity.
Madame Curie realized that this phenomenon is not just the characteristics of uranium, and it must be given a new name. Madame Curie named it "radioactive", and uranium, thorium and other substances with this special "radiation" function are called "radioactive elements".
Later, with the help of her husband, Mr. Pierre, she measured all the minerals she could collect. She wants to know what other minerals are radioactive.
In the measurement, she made another dramatic discovery. In a pitchblende mine in Czechoslovakia at that time, she found that its radioactive intensity was many times greater than originally thought.
So, where did this abnormal and excessive radioactivity come from? The contents of uranium and needles in these pitchblende can never explain the radioactive intensity she observed.
Therefore, there can only be one explanation. These asphaltene minerals contain a new element that is much more radioactive than uranium and needles, and it is not known to mankind at that time. It must be an unknown element.
Madame Curie's discovery caught Mr Pierre's attention, and the Curie couple went hand in hand and launched a powerful attack on the unknown scientific field.
In the extremely harsh laboratory, through the persistent long-term efforts of the Curie couple,1July, 898, they announced the discovery of this new element, which is 400 times more radioactive than pure uranium.
To commemorate her tortured motherland Poland, the new element was named polonium (meaning Poland).
1898 65438+In February, the Curies announced that they had discovered a second radioactive element, which was more radioactive than polonium. They named this new element.
"Radium".
However, because there were no samples and atomic weights of polonium and radium, almost no one in the scientific community at that time wanted to believe their shocking new discovery.
The Curies are determined to extract samples of polonium and radium at any cost, on the one hand, to confirm their existence, and on the other hand, to make themselves more certain.
Of course, this is a very difficult thing.
Because pitchblende containing polonium and radium is an expensive mineral, it mainly exists in the San Joachimsthal mine in Bohemia. By melting this mineral, people can extract uranium salts to make colored glass.
The Curies are a pair of intellectuals with considerable economic resources, and they are unable to pay the high cost of purchasing pitchblende. But they are not intimidated by this "obstacle" in front of them, and almost all methods have been tried.
After many twists and turns, the Austrian government officially decided to donate a ton of slag to the Curie couple first, and promised that if they needed a lot of slag in the future, they could supply it to them on the most favorable terms.
The curies breathed a long sigh of relief. They borrowed money from their friends and raised a sum of money because they had to buy this raw material and pay the freight to Paris.
They are once again caught in a long wait.
One morning, just as the sun rose, a heavy carriage like a coal truck stopped at the door of the Curie couple's house.
Madame Curie was so happy that the pitchblende she had been waiting for day and night finally came, and her dream radium was hidden here!
She quickly cut the rope with a knife, tore open the coarse cloth pocket, and deeply inserted a pair of slender hands into the brown mineral, from which she had to extract radium.
Madame Curie immediately threw herself into the heavy extraction work. She put more than 20 kilograms of waste residue into a smelting pot for heating and melting, stirred the boiling slag liquid continuously for several hours with a thick iron bar, and then extracted only one millionth of trace substances from it.
From 1898 to 1902, after countless times of extraction, dozens of tons of slag were treated, and finally 0. 1 g radium salt was obtained, and its atomic weight was determined to be 225.
Radium was finally born!
The discovery of radium triggered a real revolution in the scientific community. 1903, the curies both won the nobel prize in physics. Madame Curie's great success is by no means easy. It embodies the sweat and tears of Madame Curie, which is the crystallization of Madame Curie's painstaking efforts.
Aircraft (aircraft, aircraft, aircraft, aircraft),
Translation: Chinese? Korean (language)
plane
A heavier-than-air aircraft with wings and one or more engines can fly in the atmosphere by its own power.
Aircraft has two basic characteristics: first, its density is higher than air, and it is driven by power; The second is that the plane has fixed wings, which provide lift to make the plane soar in the sky. Those who do not have the above characteristics cannot be called airplanes. These two items are indispensable. For example, an aircraft with a density less than air is a balloon or an airship; If there is no power device and you can only glide in the air, it is called a glider; If the wings of an airplane are not fixed, a helicopter or rotorcraft generates lift by rotating the wings. So the precise definition of an airplane is: it is a powered airplane with fixed wings, which is heavier than air.
In order to make readers have a clearer understanding of airplanes, I would like to clarify some confusing terms here. In some newspapers, we can see such terms as "fixed-wing aircraft" and "fixed-wing aircraft", which actually refer to aircraft. But these nouns are not accurate. Because "fixed-wing aircraft" includes aircraft and gliders, and "fixed-wing aircraft" is a repeated title, because "aircraft" already includes the contents of fixed wings. More often, many people will say "helicopter", which is also very inappropriate, because helicopters use rotors to provide lift, which is completely different from airplanes.
Compared with other means of transportation, airplanes have many advantages:
Soon. At present, the speed of a jet airliner is about 900 kilometers per hour.
High liquidity. Aircraft flight is not blocked by mountains, rivers, deserts and oceans, and the number of flights can be increased at any time according to the number of passengers and goods.
Safe and comfortable. According to the statistics of ICAO, the average death toll of civil aviation per 1 100 million passenger kilometers is 0.04, which is 1/10 to 1% of the death toll of ordinary traffic accidents, and ranks as the safest mode of transportation alongside railway transportation.
But the plane as a means of transportation also has its own limitations:
Expensive. The fuel consumed by both the plane itself and the flight is much higher than that of other modes of transportation.
Affected by weather conditions. Although aviation technology has been able to adapt to most meteorological conditions now, severe meteorological conditions such as wind, rain, snow and fog will still affect the take-off and landing safety of aircraft.
There are restrictions on landing sites. The plane must take off and land at the airport. There are at most several airports in a city, and most of them are located in the suburbs due to the surrounding clearance conditions. Because it often takes a long transit process from the airport to the urban area, it provides inter-city transportation market space within 800 kilometers for high-speed trains.
Therefore, the aircraft is only suitable for light weight, urgent time requirements and short voyage transportation.
Danger. Although the death toll of civil airliners per 1 100 million passenger kilometers is much lower than that of other means of transport, critics believe that the journey of the aircraft itself is much longer than that of other means of transport, so this figure is lowered. According to some data, this plane is not particularly safe.
Aircraft is not only widely used in civil transportation and scientific research, but also an important weapon of modern military, so it is divided into civil aircraft and military aircraft.
In addition to passenger planes and transport planes, civil aircraft also include agricultural machines, forest protection machines, aerial survey machines, medical rescue machines, sightseeing machines, business jets, sports machines, experimental research machines, meteorological machines, stunt machines and law enforcement machines.
Aircraft can also be classified according to the shape, quantity and relative position of its components. According to the number of wings, it can be divided into monoplane, biplane and multi-wing aircraft. According to the position of the wing relative to the fuselage, it can be divided into lower monoplane, middle monoplane and upper monoplane. According to the plane shape of the wing, it can be divided into straight wing aircraft, swept wing aircraft, swept wing aircraft and delta wing aircraft. According to the position of the flat tail and whether there is a flat tail, it can be divided into normal layout aircraft (with a flat tail behind the wing), canard aircraft (with a small wing in the front fuselage) and tailless aircraft (without a flat tail); The normal layout of aircraft includes single vertical tail, double vertical tail, multiple vertical tails and V-tail. According to the type of propulsion device, it can be divided into propeller plane and jet plane; According to the engine type, it can be divided into piston aircraft, turboprop aircraft and jet aircraft; According to the number of engines, it can be divided into single-engine aircraft, double-engine aircraft and multi-engine aircraft. According to the type of landing gear, it can be divided into land aircraft, seaplane and amphibious aircraft. It can also be classified according to the flight performance of aircraft: according to the flight speed of aircraft, it can be divided into subsonic aircraft, supersonic aircraft and hypersonic aircraft According to the voyage of the aircraft, it can be divided into short-range aircraft, medium-range aircraft and long-range aircraft.
the four great inventions
compass
Compass is a simple tool to judge the direction. The predecessor of compass is Sina, one of the four great inventions in ancient China. 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.
gunpowder
Gunpowder is one of the four great inventions in ancient China. Because it is a mixture of saltpeter, sulfur and charcoal, and people used these three things as medicines to treat diseases at that time, it was named "gunpowder", which means "gunpowder".
Since the Qin and Han Dynasties, alchemists have used sulfur, saltpeter and other substances to make alchemy, and got inspiration from accidental explosions. After many practices, they found the formula of gunpowder. During the Three Kingdoms period, Ma Jun, a clever technician, wrapped gunpowder in paper, made an "explosion head battle" for entertainment and pioneered the application of gunpowder.
At the end of the Tang Dynasty, gunpowder began to be used in the military. People use trebuchets to ignite gunpowder bags and throw them out to burn the enemy. This is the most primitive artillery. Later, people wrapped spherical powder near the head of the arrow shaft and lit the fuse. Later, they shot gunpowder with bows and arrows and burned the enemy. There are also gunpowder, poison, plus some leaching, tung oil and so on. Mash them together to make poison balls. After lighting, shoot the enemy with a bow and arrow, becoming an "enemy of ten thousand people." In the Song Dynasty, people put gunpowder into bamboo tubes, tied tiny "directional sticks" behind the gunpowder, and ignited the nitrate on the fire tube, so that the gunpowder in the tube burned rapidly, generating forward thrust and making it fly to the enemy line to explode. This is the world's first gunpowder rocket. Later, muskets and guns were invented. These are primitive tubular firearms made of bamboo. They are the ancestors of modern guns.
make paper
The invention of papermaking is one of the contributions of the Chinese nation to world civilization.
About 3,500 years ago, in Shang Dynasty, China had written words carved on tortoise shell bones, called Oracle Bone Inscriptions. In the Spring and Autumn Period, tortoise shells and animal bones were replaced by bamboo chips and sawdust, which were called bamboo slips and wooden slips. Oracle Bone Inscriptions and bamboo slips are very heavy. During the Warring States Period, Hui Shi, a thinker, went out to give lectures and took five books and bamboo slips with him, so there was an allusion to being rich in learning and learning. In the Western Han Dynasty, among the court nobles, they wrote with silk or cotton paper. Silk is the general name of silk. Writing on silk is easy. It is not only much more than bamboo slips, but also can be painted on them, but it is expensive and can only be used by a few royal nobles. Paper appeared in the early Western Han Dynasty in the 2nd century BC.
be printed from type
Printing is one of the four great inventions in ancient China. Woodblock printing, which began in Sui Dynasty, was developed and perfected by Bi Sheng in Song Renzong, resulting in movable type printing, which was spread to Europe by Mongols, so Bi Sheng was later called the ancestor of printing. China's printing is the pioneer of modern human civilization, which has created conditions for the wide spread and exchange of knowledge.
Engraving printing is to carve a protruding reverse writing on a piece of wood with a knife, and then ink it on paper. Every time a new book is printed, the board has to be engraved from scratch, which is very slow. If you make a mistake, you have to engrave it again. You can imagine the hard work.
From A.D. 1004 to 1048, Bi Sheng, an engraver in the Northern Song Dynasty, made a rectangular long column with fine and sticky clay, carved characters on it, and put it into a kiln to make it into movable type. Then, according to the content of the article, put the words in order, put them on the iron frame to make a printing plate, and then put them on the fire to heat and flatten them, and you can print. Take off the movable type after printing and use it next time. This improved printing is called relief printing.
Although this printing method is primitive and simple, it is the same as the principle of modern printing, which makes printing technology enter a new era.
Later, Wang Zhen, a famous agronomist and mechanic in Yuan Dynasty, invented wooden movable type and relatively simple turntable typesetting method suitable for the complex characteristics of Chinese characters, and later invented metal movable type and improved movable type printing. Printed prints of the Tang Dynasty spread to Japan. In the late 8th century, Dalagni Sutra was completed, and then spread to the Democratic People's Republic of Korea, the United Arab Emirates and Eastern Europe. /kloc-In the 5th century, Germans learned to cast buildings with alloys, and movable type printing pioneered by Bi Sheng spread all over Europe.
Shen Kuo, a scientist and politician in the Northern Song Dynasty, once wrote an article entitled "Trapdoor" in "Talk about Meng Xi", which introduced the whole process of trapdoor printing in detail, which was easy to understand and very detailed.