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Alloy | Pewter | Pewter
The term pewter covers a variety of alloys consisting primarily of tin. As a pure metal, tin is much too soft to use for most practical purposes. However, during the Bronze Age, tin was a rare metal in many parts of Europe and the Mediterranean, so it was often valued higher than gold. To make jewellery, cutlery, or other objects from tin, workers usually alloyed it with other metals to increase strength and hardness. These metals were typically lead, antimony, bismuth or copper. These solutes were sometimes added individually in varying amounts, or added together, making a wide variety of objects, ranging from practical items such as dishes, surgical tools, candlesticks or funnels, to decorative items like ear rings and hair clips.
The earliest examples of pewter come from ancient Egypt, around 1450 BC. The use of pewter was widespread across Europe, from France to Norway and Britain (where most of the ancient tin was mined) to the Near East.Hull, Charles (1992) Pewter. Shire Publications. pp. 3–4; The alloy was also used in China and the Far East, arriving in Japan around 800 AD, where it was used for making objects like ceremonial vessels, tea canisters, or chalices used in shinto shrines.Brinkley, Frank (1904) Japan and China: Japan, its history, arts, and literature. Oxford University. p. 317 |
Alloy | Iron | Iron
thumb|Puddling in China, . Opposite to most alloying processes, liquid pig-iron is poured from a blast furnace into a container and stirred to remove carbon, which diffuses into the air forming carbon dioxide, leaving behind a mild steel to wrought iron
The first known smelting of iron began in Anatolia, around 1800 BC. Called the bloomery process, it produced very soft but ductile wrought iron. By 800 BC, iron-making technology had spread to Europe, arriving in Japan around 700 AD. Pig iron, a very hard but brittle alloy of iron and carbon, was being produced in China as early as 1200 BC, but did not arrive in Europe until the Middle Ages. Pig iron has a lower melting point than iron, and was used for making cast-iron. However, these metals found little practical use until the introduction of crucible steel around 300 BC. These steels were of poor quality, and the introduction of pattern welding, around the 1st century AD, sought to balance the extreme properties of the alloys by laminating them, to create a tougher metal. Around 700 AD, the Japanese began folding bloomery-steel and cast-iron in alternating layers to increase the strength of their swords, using clay fluxes to remove slag and impurities. This method of Japanese swordsmithing produced one of the purest steel-alloys of the ancient world.Smith, Cyril (1960) History of metallography. MIT Press. pp. 2–4. .
While the use of iron started to become more widespread around 1200 BC, mainly because of interruptions in the trade routes for tin, the metal was much softer than bronze. However, very small amounts of steel, (an alloy of iron and around 1% carbon), was always a byproduct of the bloomery process. The ability to modify the hardness of steel by heat treatment had been known since 1100 BC, and the rare material was valued for the manufacture of tools and weapons. Because the ancients could not produce temperatures high enough to melt iron fully, the production of steel in decent quantities did not occur until the introduction of blister steel during the Middle Ages. This method introduced carbon by heating wrought iron in charcoal for long periods of time, but the absorption of carbon in this manner is extremely slow thus the penetration was not very deep, so the alloy was not homogeneous. In 1740, Benjamin Huntsman began melting blister steel in a crucible to even out the carbon content, creating the first process for the mass production of tool steel. Huntsman's process was used for manufacturing tool steel until the early 1900s.Roberts, George Adam; Krauss, George; Kennedy, Richard and Kennedy, Richard L. (1998) Tool steels . ASM International. pp. 2–3. .
The introduction of the blast furnace to Europe in the Middle Ages meant that people could produce pig iron in much higher volumes than wrought iron. Because pig iron could be melted, people began to develop processes to reduce carbon in liquid pig iron to create steel. Puddling had been used in China since the first century, and was introduced in Europe during the 1700s, where molten pig iron was stirred while exposed to the air, to remove the carbon by oxidation. In 1858, Henry Bessemer developed a process of steel-making by blowing hot air through liquid pig iron to reduce the carbon content. The Bessemer process led to the first large scale manufacture of steel.
Steel is an alloy of iron and carbon, but the term alloy steel usually only refers to steels that contain other elements— like vanadium, molybdenum, or cobalt—in amounts sufficient to alter the properties of the base steel. Since ancient times, when steel was used primarily for tools and weapons, the methods of producing and working the metal were often closely guarded secrets. Even long after the Age of Enlightenment, the steel industry was very competitive and manufacturers went through great lengths to keep their processes confidential, resisting any attempts to scientifically analyze the material for fear it would reveal their methods. For example, the people of Sheffield, a center of steel production in England, were known to routinely bar visitors and tourists from entering town to deter industrial espionage. Thus, almost no metallurgical information existed about steel until 1860. Because of this lack of understanding, steel was not generally considered an alloy until the decades between 1930 and 1970 (primarily due to the work of scientists like William Chandler Roberts-Austen, Adolf Martens, and Edgar Bain), so "alloy steel" became the popular term for ternary and quaternary steel-alloys.Sheffield Steel and America: A Century of Commercial and Technological Independence By Geoffrey Tweedale – Cambridge University Press 1987 Page 57–62Experimental Techniques in Materials and Mechanics By C. Suryanarayana – CRC Press 2011 p. 202
After Benjamin Huntsman developed his crucible steel in 1740, he began experimenting with the addition of elements like manganese (in the form of a high-manganese pig-iron called spiegeleisen), which helped remove impurities such as phosphorus and oxygen; a process adopted by Bessemer and still used in modern steels (albeit in concentrations low enough to still be considered carbon steel).Tool Steels, 5th Edition By George Adam Roberts, Richard Kennedy, G. Krauss – ASM International 1998 p. 4 Afterward, many people began experimenting with various alloys of steel without much success. However, in 1882, Robert Hadfield, being a pioneer in steel metallurgy, took an interest and produced a steel alloy containing around 12% manganese. Called mangalloy, it exhibited extreme hardness and toughness, becoming the first commercially viable alloy-steel. Afterward, he created silicon steel, launching the search for other possible alloys of steel.Sheffield Steel and America: A Century of Commercial and Technological Independence By Geoffrey Tweedale – Cambridge University Press 1987 pp. 57–62
Robert Forester Mushet found that by adding tungsten to steel it could produce a very hard edge that would resist losing its hardness at high temperatures. "R. Mushet's special steel" (RMS) became the first high-speed steel.Sheffield Steel and America: A Century of Commercial and Technological Independence By Geoffrey Tweedale – Cambridge University Press 1987 pp. 66–68 Mushet's steel was quickly replaced by tungsten carbide steel, developed by Taylor and White in 1900, in which they doubled the tungsten content and added small amounts of chromium and vanadium, producing a superior steel for use in lathes and machining tools. In 1903, the Wright brothers used a chromium-nickel steel to make the crankshaft for their airplane engine, while in 1908 Henry Ford began using vanadium steels for parts like crankshafts and valves in his Model T Ford, due to their higher strength and resistance to high temperatures.Metallurgy for the Non-Metallurgist by Harry Chandler – ASM International 1998 Page 3–5 In 1912, the Krupp Ironworks in Germany developed a rust-resistant steel by adding 21% chromium and 7% nickel, producing the first stainless steel.Sheffield Steel and America: A Century of Commercial and Technological Independence By Geoffrey Tweedale – Cambridge University Press 1987 p. 75 |
Alloy | Others | Others
Due to their high reactivity, most metals were not discovered until the 19th century. A method for extracting aluminium from bauxite was proposed by Humphry Davy in 1807, using an electric arc. Although his attempts were unsuccessful, by 1855 the first sales of pure aluminium reached the market. However, as extractive metallurgy was still in its infancy, most aluminium extraction-processes produced unintended alloys contaminated with other elements found in the ore; the most abundant of which was copper. These aluminium-copper alloys (at the time termed "aluminium bronze") preceded pure aluminium, offering greater strength and hardness over the soft, pure metal, and to a slight degree were found to be heat treatable.Aluminium: Its History, Occurrence, Properties, Metallurgy and Applications by Joseph William Richards – Henry Cairy Baird & Co 1887 Page 25–42 However, due to their softness and limited hardenability these alloys found little practical use, and were more of a novelty, until the Wright brothers used an aluminium alloy to construct the first airplane engine in 1903. During the time between 1865 and 1910, processes for extracting many other metals were discovered, such as chromium, vanadium, tungsten, iridium, cobalt, and molybdenum, and various alloys were developed.Metallurgy: 1863–1963 by W.H. Dennis – Routledge 2017
Prior to 1910, research mainly consisted of private individuals tinkering in their own laboratories. However, as the aircraft and automotive industries began growing, research into alloys became an industrial effort in the years following 1910, as new magnesium alloys were developed for pistons and wheels in cars, and pot metal for levers and knobs, and aluminium alloys developed for airframes and aircraft skins were put into use. The Doehler Die Casting Co. of Toledo, Ohio were known for the production of Brastil, a high tensile corrosion resistant bronze alloy.Woldman’s Engineering Alloys, 9th Edition 1936, American Society for Metals, |
Alloy | See also | See also
Alloy broadening
CALPHAD
Ideal mixture
List of alloys |
Alloy | References | References |
Alloy | Bibliography | Bibliography
|
Alloy | External links | External links
Category:Metallurgy
Category:Chemistry |
Alloy | Table of Content | pp-semi-indef, Characteristics, Theory, Heat treatment, Mechanisms, History and examples, Meteoric iron, Bronze and brass, Amalgams, Precious metals, Pewter, Iron, Others, See also, References, Bibliography, External links |
Artistic revolution | more citations needed | Throughout history, forms of art have gone through periodic abrupt changes called artistic revolutions. Movements have come to an end to be replaced by a new movement markedly different in striking ways. |
Artistic revolution | Scientific and technological | Scientific and technological
1
Not all artistic revolutions were political. Sometimes, science and technological innovations have brought about unforeseen transformations in the works of artists. The stylistic revolution known as Impressionism, by painters eager to more accurately capture the changing colors of light and shadow, is inseparable from discoveries and inventions in the mid-19th century in which the style was born.
Michel Eugène Chevreul, a French chemist hired as director of dyes at a French tapestry works, began to investigate the optical nature of color in order to improve color in fabrics. Chevreul realized It was the eye, and not the dye, that had the greatest influence on color, and from this, he revolutionized color theory by grasping what came to be called the law of simultaneous contrast: that colors mutually influence one another when juxtaposed, each imposing its own complementary color on the other. The French painter Eugène Delacroix, who had been experimenting with what he called broken tones, embraced Chevreul's book, The Law of Contrast of Color (1839) with its explanations of how juxtaposed colors can enhance or diminish each other, and his exploration of all the visible colors of the spectrum. Inspired by Chevreul's 1839 treatise, Delacroix passed his enthusiasm on to the young artists who were inspired by him. It was Chevreul who led the Impressionists to grasp that they should apply separate brushstrokes of pure color to a canvas and allow the viewer's eye to combine them optically.
They were aided greatly in this by innovations in oil paint itself. Since the Renaissance, painters had to grind pigment, add oil and thus create their own paints; these time-consuming paints also quickly dried out, making studio painting a necessity for large works, and limiting painters to mix one or two colors at a time and fill in an entire area using just that one color before it dried out. In 1841, a little-known American painter named John G. Rand invented a simple improvement without which the Impressionist movement could not have occurred: the small, flexible tin tube with removable cap in which oil paints could be stored.http://www.smithsonianmag.com/arts-culture/never-underestimate-the-power-of-a-paint-tube-36637764/?no-ist, May 2013, by Perry Hurt Oil paints kept in such tubes stayed moist, usable, and portable. For the first time since the Renaissance, painters were not trapped by the time frame of how quickly oil paint dried.
Paints in tubes could be easily loaded up and carried out into the real world, to directly observe the play of color and natural light, in shadow and movement, to paint in the moment. Selling the oil paint in tubes also brought about the arrival of dazzling new pigments - chrome yellow, cadmium blue - invented by 19th century industrial chemists. The tubes freed the Impressionists to paint quickly, and across an entire canvas, rather than carefully delineated single-color sections at a time; in short, to sketch directly in oil - racing across the canvas in every color that came to hand and thus inspiring their name of "impressionists" - since such speedy, bold brushwork and dabs of separate colors made contemporary critics think their paintings were mere impressions, not finished paintings, which were to have no visible brush marks at all, seamless under layers of varnish.
Pierre-Auguste Renoir said, “Without colors in tubes, there would be no Cézanne, no Monet, no Pissarro, and no Impressionism.”
Finally, the careful, hyper-realistic techniques of French neo-classicism were seen as stiff and lifeless when compared to the remarkable new vision of the world as seen through the new invention of photography by the mid-1850s. It was not merely that the increasing ability of this new invention, particularly by the French inventor Daguerre, made the realism of the painted image redundant as he deliberately competed in the Paris diorama with large-scale historical paintings."Speculating Daguerre: Art and Enterprise in the Work of L. J. M. Daguerre" by Stephen C. Pinson, Chicago, (2012) p. 1-12 The neo-classical subject matter, limited by Academic tradition to Greek and Roman legends, historical battles and Biblical stories, seemed oppressively clichéd and limited to artists eager to explore the actual world in front of their own eyes revealed by the camera - daily life, candid groupings of everyday people doing simple things, Paris itself, rural landscapes and most particularly the play of captured light - not the imaginary lionizing of unseen past events.Review of "The Lens of Impressionism," at University of Michigan Museum of Art, October- Dec. 2009 by Simon Kelly, Volume 9, Issue 1 Spring 2010, http://www.19thc-artworldwide.org/spring10/the-lens-of-impressionism Early photographs influenced Impressionist style by its use of asymmetry, cropping and most obviously the blurring of motion, as inadvertently captured in the very slow speeds of early photography.
Edgar Degas, Claude Monet, Pierre-Auguste Renoir - in their framing, use of color, light and shadow, subject matter - put these innovations to work to create a new language of visual beauty and meaning. |
Artistic revolution | Faking revolution: the CIA and Abstract Expressionism | Faking revolution: the CIA and Abstract Expressionism
Their initial break with realism into an exploration of light, color and the nature of paint was brought to an ultimate conclusion by the abstract expressionists who broke away from recognizable content of any kind into works of pure shape, color and painterliness which emerged at the end of the Second World War. At first thought of as primitive, inept works - as in "my four year old could do that - these works were misunderstood and neglected until given critical and support by the rise of art journalists and critics who championed their work in the 1940s and 50s, expressing the power of such work in aesthetic terms the artists themselves seldom used, or even understood. Jackson Pollock who pioneered splatter painting, dispensing with a paint brush altogether, soon became lionized as the angry young man in a large spread in Life magazine.
In fact, in a deliberate, secret and successful effort to separate artistic revolutions from political ones, abstract expressionists like Pollock, Robert Motherwell, Willem de Kooning and Mark Rothko, while seemingly difficult, pathbreaking artists, were in fact secretly supported for twenty years by the Central Intelligence Agency (CIA) in a Cold War policy begun in 1947 to prove that the United States could foster more artistic freedom than the Soviet bloc. "It was recognized that Abstract Expressionism was the kind of art that made Socialist Realism look even more stylized and rigid and confined than it was," said former CIA case worker Donald Jameson, who finally broke the silence on this program in 1995. Ironically, the covert CIA support for these radical works was required because an attempt to use government funds for a European tour of these works during the Truman administration led to a public uproar in conservative McCarthy-era America, with Truman famously remarking, "If that's art, I'm a Hottentot." Thus, the program was hidden under the guise of fabricated foundations and the support of wealthy patrons who were actually using CIA funds, not their own, to sponsor traveling exhibitions of American abstract expressionists all over the world, publish books and articles praising them and to purchase and exhibit abstract expressionist works in major American and British museums. Thomas Braden, in charge of these cultural programs for the CIA, in the early years of the Cold War, had formerly been executive secretary of the Museum of Modern Art, America's leading institution for 20th century art and the charges of collusion between the two echoed for many years after this program was revealed, though most of the artists involved had no idea they were being used in this way and were furious when they found out. |
Artistic revolution | See also | See also
Cultural movement |
Artistic revolution | References | References
Category:History of art
Category:Revolutions by type |
Artistic revolution | Table of Content | more citations needed, Scientific and technological, Faking revolution: the CIA and Abstract Expressionism, See also, References |
Agrarianism | Short description | Agrarianism is a social and political philosophy that advocates for rural development, a rural agricultural lifestyle, family farming, widespread property ownership, and political decentralization. Those who adhere to agrarianism tend to value traditional forms of local community over urban modernity. Agrarian political parties sometimes aim to support the rights and sustainability of small farmers and poor peasants against the wealthy, powerful and famous in society. |
Agrarianism | Philosophy | Philosophy
Some scholars suggest that agrarianism espouses the superiority of rural society to urban society and the independent farmer as superior to the paid worker, and sees farming as a way of life that can shape the ideal social values.Thompson, Paul. 2010. "Interview Eighteen" in Sustainability Ethics: 5 Questions Ed. Ryne Raffaelle, Wade Robinson, and Evan Selinger. United States: Automatic Press It stresses the superiority of a simpler rural life in comparison to the complexity of urban life. For example, M. Thomas Inge defines agrarianism by the following basic tenets:M. Thomas Inge, ed. Agrarianism in American Literature (1969), introduction; paraphrased
Farming is the sole occupation that offers total independence and self-sufficiency.
Urban life, fascism, capitalism, and technology destroy independence and dignity and foster vice and weakness.
The agricultural community, with its fellowship of labor and co-operation, is the model society.
The farmer has a solid, stable position in the world order. They have "a sense of identity, a sense of historical and religious tradition, a feeling of belonging to a concrete family, place, and region, which are psychologically and culturally beneficial." The harmony of their life checks the encroachments of a fragmented, alienated modern society.
Cultivation of the soil "has within it a positive spiritual good" and from it the cultivator acquires the virtues of "honor, manliness, self-reliance, courage, moral integrity, and hospitality." They result from a direct contact with nature and, through nature, a closer relationship to God. The agrarian is blessed in that they follow the example of God in creating order out of chaos. |
Agrarianism | History | History
The philosophical roots of agrarianism include European and Chinese philosophers. The Chinese school of Agriculturalism (农家/農家) was a philosophy that advocated peasant utopian communalism and egalitarianism. In societies influenced by Confucianism that had as its foundation that humans are innately good, the farmer was considered an esteemed productive member of society, but merchants who made money were looked down upon. That influenced European intellectuals like François Quesnay, an avid Confucianist and advocate of China's agrarian policies, in forming the French agrarian philosophy of physiocracy.L.A. Maverick, "Chinese Influences upon the Physiocrats," Economic History, 3:54–67 (February 1938), The physiocrats, along with the ideas of John Locke and the Romantic Era, formed the basis of modern European and American agrarianism. |
Agrarianism | Types of agrarianism | Types of agrarianism |
Agrarianism | Physiocracy | Physiocracy |
Agrarianism | Jeffersonian democracy | Jeffersonian democracy
thumb|right|200px|Thomas Jefferson and his supporters idealised farmers as the citizens that the American Republic should be formed around.
The United States president Thomas Jefferson was an agrarian who based his ideas about the budding American democracy around the notion that farmers are "the most valuable citizens" and the truest republicans.Thomas P. Govan, "Agrarian and Agrarianism: A Study in the Use and Abuse of Words," Journal of Southern History, Vol. 30#1 (Feb. 1964), pp. 35–47 Jefferson and his support base were committed to American republicanism, which they saw as being in opposition to monarchy, aristocracy, clericalism and corruption, and which prioritized morality and virtue, exemplified by the "yeoman farmer", "planters", and the "plain folk". In praising the rural farmfolk, the Jeffersonians felt that financiers, bankers and industrialists created "cesspools of corruption" in the cities and should thus be avoided.Elkins and McKitrick. (1995) ch 5; Wallace Hettle, The Peculiar Democracy: Southern Democrats in Peace and Civil War (2001) p. 15
The Jeffersonians sought to align the American economy more with agriculture than industry. Part of their motive to do so was Jefferson's fear that the over-industrialization of America would create a class of wage slaves who relied on their employers for income and sustenance. In turn, these workers would cease to be independent voters as their vote could be manipulated by said employers. To counter this, Jefferson introduced, as scholar Clay Jenkinson noted, "a graduated income tax that would serve as a disincentive to vast accumulations of wealth and would make funds available for some sort of benign redistribution downward" and tariffs on imported articles, which were mainly purchased by the wealthy.Jenkinson, Becoming Jefferson's People, p. 26 In 1811, Jefferson, writing to a friend, explained: "these revenues will be levied entirely on the rich... . the rich alone use imported articles, and on these alone the whole taxes of the general government are levied. the poor man ... pays not a farthing of tax to the general government, but on his salt."
There is general agreement that the substantial United States' federal policy of offering land grants (such as thousands of gifts of land to veterans) had a positive impact on economic development in the 19th century.Whaples, R. (1995). Where is there consensus among American economic historians? The results of a survey on forty propositions. The Journal of Economic History, 55(1), 139–154. |
Agrarianism | Agrarian socialism | Agrarian socialism
Agrarian socialism is a form of agrarianism that is anti-capitalist in nature and seeks to introduce socialist economic systems in their stead. |
Agrarianism | Zapatismo | Zapatismo
right|thumb|Emiliano Zapata fought in the Mexican Revolution in the name of the Mexican peasants and sought to introduce reforms such as land redistribution.
Notable agrarian socialists include Emiliano Zapata who was a leading figure in the Mexican Revolution. As part of the Liberation Army of the South, his group of revolutionaries fought on behalf of the Mexican peasants, whom they saw as exploited by the landowning classes. Zapata published the Plan of Ayala, which called for significant land reforms and land redistribution in Mexico as part of the revolution. Zapata was killed and his forces crushed over the course of the Revolution, but his political ideas lived on in the form of Zapatismo.
Zapatismo would form the basis for neozapatismo, the ideology of the Zapatista Army of National Liberation. Known as Ejército Zapatista de Liberación Nacional or EZLN in Spanish, EZLN is a far-left libertarian socialist political and militant group that emerged in the state of Chiapas in southmost Mexico in 1994. EZLN and Neozapatismo, as explicit in their name, seek to revive the agrarian socialist movement of Zapata, but fuse it with new elements such as a commitment to indigenous rights and community-level decision making.
Subcommander Marcos, a leading member of the movement, argues that the peoples' collective ownership of the land was and is the basis for all subsequent developments the movement sought to create:...When the land became property of the peasants ... when the land passed into the hands of those who work it ... [This was] the starting point for advances in government, health, education, housing, nutrition, women's participation, trade, culture, communication, and information ...[it was] recovering the means of production, in this case, the land, animals, and machines that were in the hands of large property owners."See The Zapatistas' Dignified Rage: Final Public Speeches of Subcommander Marcos. Edited by Nick Henck. Translated by Henry Gales. (Chico: AK Press, 2018), pp. 81–82. |
Agrarianism | Maoism | Maoism
Maoism, the far-left ideology of Mao Zedong and his followers, places a heavy emphasis on the role of peasants in its goals. In contrast to other Marxist schools of thought which normally seek to acquire the support of urban workers, Maoism sees the peasantry as key. Believing that "political power grows out of the barrel of a gun", Maoism saw the Chinese Peasantry as the prime source for a Marxist vanguard because it possessed two qualities: (i) they were poor, and (ii) they were a political blank slate; in Mao's words, "A clean sheet of paper has no blotches, and so the newest and most beautiful words can be written on it".Gregor, A. James; Chang, Maria Hsia (1978). "Maoism and Marxism in Comparative Perspective". The Review of Politics. 40: 3. pp. 307–327. During the Chinese Civil War and the Second Sino-Japanese War, Mao and the Chinese Communist Party made extensive use of peasants and rural bases in their military tactics, often eschewing the cities.
Following the eventual victory of the Communist Party in both wars, the countryside and how it should be run remained a focus for Mao. In 1958, Mao launched the Great Leap Forward, a social and economic campaign which, amongst other things, altered many aspects of rural Chinese life. It introduced mandatory collective farming and forced the peasantry to organize itself into communal living units which were known as people's communes. These communes, which consisted of 5,000 people on average, were expected to meet high production quotas while the peasants who lived on them adapted to this radically new way of life. The communes were run as co-operatives where wages and money were replaced by work points. Peasants who criticised this new system were persecuted as "rightists" and "counter-revolutionaries". Leaving the communes was forbidden and escaping from them was difficult or impossible, and those who attempted it were subjected to party-orchestrated "public struggle sessions," which further jeopardized their survival.Thaxton, Ralph A. Jr (2008). Catastrophe and Contention in Rural China: Mao's Great Leap Forward Famine and the Origins of Righteous Resistance in Da Fo Village . Cambridge University Press. p. 3. . These public criticism sessions were often used to intimidate the peasants into obeying local officials and they often devolved into little more than public beatings.Thaxton 2008, p. 212.
On the communes, experiments were conducted in order to find new methods of planting crops, efforts were made to construct new irrigation systems on a massive scale, and the communes were all encouraged to produce steel backyard furnaces as part of an effort to increase steel production. However, following the Anti-Rightist Campaign, Mao had instilled a mass distrust of intellectuals into China, and thus engineers often were not consulted with regard to the new irrigation systems and the wisdom of asking untrained peasants to produce good quality steel from scrap iron was not publicly questioned. Similarly, the experimentation with the crops did not produce results. In addition to this the Four Pests Campaign was launched, in which the peasants were called upon to destroy sparrows and other wild birds that ate crop seeds, in order to protect fields. Pest birds were shot down or scared away from landing until they dropped from exhaustion. This campaign resulted in an ecological disaster that saw an explosion of the vermin population, especially crop-eating insects, which was consequently not in danger of being killed by predators.
None of these new systems were working, but local leaders did not dare to state this, instead, they falsified reports so as not to be punished for failing to meet the quotas. In many cases they stated that they were greatly exceeding their quotas, and in turn, the Chinese state developed a completely false sense of success with regard to the commune system.
All of this culminated in the Great Chinese Famine, which began in 1959, lasted 3 years, and saw an estimated 15 to 30 million Chinese people die.Holmes, Leslie. Communism: A Very Short Introduction (Oxford University Press 2009). . p. 32 "Most estimates of the number of Chinese people who died range from 15 to 30 million." A combination of bad weather and the new, failed farming techniques that were introduced by the state led to massive shortages of food. By 1962, the Great Leap Forward was declared to be at an end.
In the late 1960s and early 1970s, Mao once again radically altered life in rural China with the launching of the Down to the Countryside Movement. As a response to the Great Chinese Famine, the Chinese President Liu Shaoqi began "sending down" urban youths to rural China in order to recover its population losses and alleviate overcrowding in the cities. However, Mao turned the practice into a political crusade, declaring that the sending down would strip the youth of any bourgeois tendencies by forcing them to learn from the unprivileged rural peasants. In reality, it was the Communist Party's attempt to reign in the Red Guards, who had become uncontrollable during the course of the Cultural Revolution. 10% of the 1970 urban population of China was sent out to remote rural villages, often in Inner Mongolia. The villages, which were still poorly recovering from the effects of the Great Chinese Famine, did not have the excess resources that were needed to support the newcomers. Furthermore, the so-called "sent-down youth" had no agricultural experience and as a result, they were unaccustomed to the harsh lifestyle that existed in the countryside, and their unskilled labor in the villages provided little benefit to the agricultural sector. As a result, many of the sent-down youth died in the countryside. The relocation of the youths was originally intended to be permanent, but by the end of the Cultural Revolution, the Communist Party relented and some of those who had the capacity to return to the cities were allowed to do so.
In imitation of Mao's policies, the Khmer Rouge of Cambodia (who were heavily funded and supported by the People's Republic of China) created their own version of the Great Leap Forward which was known as "Maha Lout Ploh". With the Great Leap Forward as its model, it had similarly disastrous effects, contributing to what is now known as the Cambodian genocide. As a part of the Maha Lout Ploh, the Khmer Rouge sought to create an entirely agrarian socialist society by forcibly relocating 100,000 people to move from Cambodia's cities into newly created communes. The Khmer Rouge leader, Pol Pot sought to "purify" the country by setting it back to "Year Zero", freeing it from "corrupting influences". Besides trying to completely de-urbanize Cambodia, ethnic minorities were slaughtered along with anyone else who was suspected of being a "reactionary" or a member of the "bourgeoisie", to the point that wearing glasses was seen as grounds for execution. The killings were only brought to an end when Cambodia was invaded by the neighboring socialist nation of Vietnam, whose army toppled the Khmer Rouge. However, with Cambodia's entire society and economy in disarray, including its agricultural sector, the country still plunged into renewed famine due to vast food shortages. However, as international journalists began to report on the situation and send images of it out to the world, a massive international response was provoked, leading to one of the most concentrated relief efforts of its time. |
Agrarianism | Notable agrarian parties | Notable agrarian parties
Peasant parties first appeared across Eastern Europe between 1860 and 1910, when commercialized agriculture and world market forces disrupted traditional rural society, and the railway and growing literacy facilitated the work of roving organizers. Agrarian parties advocated land reforms to redistribute land on large estates among those who work it. They also wanted village cooperatives to keep the profit from crop sales in local hands and credit institutions to underwrite needed improvements. Many peasant parties were also nationalist parties because peasants often worked their land for the benefit of landlords of different ethnicity.
Peasant parties rarely had any power before World War I but some became influential in the interwar era, especially in Bulgaria and Czechoslovakia. For a while, in the 1920s and the 1930s, there was a Green International (International Agrarian Bureau) based on the peasant parties in Bulgaria, Czechoslovakia, Poland, and Serbia. It functioned primarily as an information center that spread the ideas of agrarianism and combating socialism on the left and landlords on the right and never launched any significant activities. |
Agrarianism | Europe | Europe |
Agrarianism | Bulgaria | Bulgaria
In Bulgaria, the Bulgarian Agrarian National Union (BZNS) was organized in 1899 to resist taxes and build cooperatives. BZNS came to power in 1919 and introduced many economic, social, and legal reforms. However, conservative forces crushed BZNS in a 1923 coup and assassinated its leader, Aleksandar Stamboliyski (1879–1923). BZNS was made into a communist puppet group until 1989, when it reorganized as a genuine party. |
Agrarianism | Czechoslovakia | Czechoslovakia
In Czechoslovakia, the Republican Party of Agricultural and Smallholder People often shared power in parliament as a partner in the five-party pětka coalition. The party's leader, Antonín Švehla (1873–1933), was prime minister several times. It was consistently the strongest party, forming and dominating coalitions. It moved beyond its original agrarian base to reach middle-class voters. The party was banned by the National Front after the Second World War.Sharon Werning Rivera, "Historical cleavages or transition mode? Influences on the emerging party systems in Poland, Hungary and Czechoslovakia." Party Politics (1996) 2#2 : 177-208. |
Agrarianism | France | France
In France, the Hunting, Fishing, Nature, Tradition party is a moderate conservative, agrarian party, reaching a peak of 4.23% in the 2002 French presidential election. It would later on become affiliated to France's main conservative party, Union for a Popular Movement. More recently, the Resistons! movement of Jean Lassalle espoused agrarianism. |
Agrarianism | Hungary | Hungary
In Hungary, the first major agrarian party, the small-holders party was founded in 1908. The party became part of the government in the 1920s but lost influence in the government. A new party, the Independent Smallholders, Agrarian Workers and Civic Party was established in 1930 with a more radical program representing larger scale land redistribution initiatives. They implemented this program together with the other coalition parties after WWII. However, after 1949 the party was outlawed when a one-party system was introduced. They became part of the government again 1990–1994, and 1998–2002 after which they lost political support. The ruling Fidesz party has an agrarian faction, and promotes agrarian interest since 2010 with the emphasis now placed on supporting larger family farms versus small-holders. |
Agrarianism | Ireland | Ireland
thumb|Land League poster
In the late 19th century, the Irish National Land League aimed to abolish landlordism in Ireland and enable tenant farmers to own the land they worked on. The "Land War" of 1878–1909 led to the Irish Land Acts, ending absentee landlords and ground rent and redistributing land among peasant farmers.
Post-independence, the Farmers' Party operated in the Irish Free State from 1922, folding into the National Centre Party in 1932. It was mostly supported by wealthy farmers in the east of Ireland.
Clann na Talmhan (Family of the Land; also called the National Agricultural Party) was founded in 1938. They focused more on the poor smallholders of the west, supporting land reclamation, afforestation, social democracy and rates reform. They formed part of the governing coalition of the Government of the 13th Dáil and Government of the 15th Dáil. Economic improvement in the 1960s saw farmers vote for other parties and Clann na Talmhan disbanded in 1965. |
Agrarianism | Kazakhstan | Kazakhstan
In Kazakhstan, the Peasants' Union, originally a communist organization, was formed as one of first agrarian parties in independent Kazakhstan and would win four seats in the 1994 legislative election. The Agrarian Party of Kazakhstan, led by Romin Madinov, was founded in 1999, which favored the privatization of agricultural land, developments towards rural infrastructure, as well as changes in the tax system in agrarian economy. The party would go on to win three Mäjilis seats in the 1999 legislative election and eventually unite with the Civic Party of Kazakhstan to form the pro-government Agrarian-Industrial Union of Workers (AIST) bloc that would be chaired by Madinov for the 2004 legislative election, with the AIST bloc winning 11 seats in the Mäjilis. From there, the bloc remained short-lived as it would merge with the ruling Nur Otan party in 2006.
Several other parties in Kazakhstan over the years have embraced agrarian policies in their programs in an effort to appeal towards a large rural Kazakh demographic base, which included Amanat, ADAL, and Respublica.
Since late 2000s, the "Auyl" People's Democratic Patriotic Party remains the largest and most influential agrarian-oriented party in Kazakhstan, as its presidential candidate Jiguli Dairabaev had become the second-place frontrunner in the 2022 presidential election after sweeping 3.4% of the vote. In the 2023 legislative election, the Auyl party for the first time was represented the parliament after winning nine seats in the lower chamber Mäjilis. The party raises rural issues in regard to decaying villages, rural development and the agro-industrial complex, the issues of social security of the rural population, and has consistently opposed the ongoing rural flight in Kazakhstan. |
Agrarianism | Latvia | Latvia
In Latvia, the Union of Greens and Farmers is supportive of traditional small farms and perceives them as more environmentally friendly than large-scale farming: Nature is threatened by development, while small farms are threatened by large industrial-scale farms. |
Agrarianism | Lithuania | Lithuania
In Lithuania, the government led by the Lithuanian Farmers and Greens Union was in power between 2016 and 2020. |
Agrarianism | Nordic countries | Nordic countries
thumb|220px|As well as sharing similar backgrounds and policies, Nordic agrarian parties share the use of a four leaf clover as their primary symbol |
Agrarianism | Poland | Poland
In Poland, the Polish People's Party (Polskie Stronnictwo Ludowe, PSL) traces its tradition to an agrarian party in Austro-Hungarian-controlled Galician Poland. After the fall of the communist regime, PSL's biggest success came in 1993 elections, where it won 132 out of 460 parliamentary seats. Since then, PSL's support has steadily declined, until 2019, when they formed Polish Coalition with an anti-establishment, direct democracy Kukiz'15 party, and managed to get 8.5% of popular vote. Moreover, PSL tends to get much better results in local elections. In 2014 elections they have managed to get 23.88% of votes.
The right-wing Law and Justice party has also become supportive of agrarian policies in recent years and polls show that most of their support comes from rural areas. AGROunia resembles the features of agrarianism. |
Agrarianism | Romania | Romania
In Romania, older party parties from Transylvania, Moldavia, and Wallachia merged to become the National Peasants' Party (PNȚ) in 1926. Iuliu Maniu (1873–1953) was a prime minister with an agrarian cabinet from 1928 to 1930 and briefly in 1932–1933, but the Great Depression made proposed reforms impossible. The communist administration dissolved the party in 1947 (along with other historical parties such as the National Liberal Party), but it reformed in 1989 after they fell from power.
The reformed party, which also incorporated elements of Christian democracy in its ideology, governed Romania as part of the Romanian Democratic Convention (CDR) between 1996 and 2000. |
Agrarianism | Serbia | Serbia
In Serbia, Nikola Pašić (1845–1926) and his People's Radical Party dominated Serbian politics after 1903. The party also monopolized power in Yugoslavia from 1918 to 1929. During the dictatorship of the 1930s, the prime minister was from that party. |
Agrarianism | Ukraine | Ukraine
In Ukraine, the Radical Party of Oleh Lyashko has promised to purify the country of oligarchs "with a pitchfork". The party advocates a number of traditional left-wing positions (a progressive tax structure, a ban on agricultural land sale and eliminating the illegal land market, a tenfold increase in budget spending on health, setting up primary health centres in every village)The Communist Party May Be on Its Last Legs, But Social Populism is Still Alive, The Ukrainian Week (23 October 2014) and mixes them with strong nationalist sentiments. |
Agrarianism | United Kingdom | United Kingdom
In land law the heyday of English, Irish (and thus Welsh) agrarianism was to 1603, led by the Tudor royal advisors, who sought to maintain a broad pool of agricultural commoners from which to draw military men, against the interests of larger landowners who sought enclosure (meaning complete private control of common land, over which by custom and common law lords of the manor always enjoyed minor rights). The heyday was eroded by hundreds of Acts of Parliament to expressly permit enclosure, chiefly from 1650 to the 1810s. Politicians standing strongly as reactionaries to this included the Levellers, those anti-industrialists (Luddites) going beyond opposing new weaving technology and, later, radicals such as William Cobbett.
A high level of net national or local self-sufficiency has a strong base in campaigns and movements. In the 19th century such empowered advocates included Peelites and most Conservatives. The 20th century saw the growth or start of influential non-governmental organisations, such as the National Farmers' Union of England and Wales, Campaign for Rural England, Friends of the Earth (EWNI) and of the England Wales, Scottish and Northern Irish political parties prefixed by and focussed on Green politics. The 21st century has seen decarbonisation already in electricity markets. Following protests and charitable lobbying local food has seen growing market share, sometimes backed by wording in public policy papers and manifestos. The UK has many sustainability-prioritising businesses, green charity campaigns, events and lobby groups ranging from espousing allotment gardens (hobby community farming) through to a clear policy of local food and/or self-sustainability models. |
Agrarianism | Oceania | Oceania |
Agrarianism | Australia | Australia
Historian F.K. Crowley finds that:
The National Party of Australia (formerly called the Country Party), from the 1920s to the 1970s, promulgated its version of agrarianism, which it called "countrymindedness". The goal was to enhance the status of the graziers (operators of big sheep stations) and small farmers and justified subsidies for them.Rae Wear, "Countrymindedness Revisited," (Australian Political Science Association, 1990) online edition |
Agrarianism | New Zealand | New Zealand
The New Zealand Liberal Party aggressively promoted agrarianism in its heyday (1891–1912). The landed gentry and aristocracy ruled Britain at this time. New Zealand never had an aristocracy but its wealthy landowners largely controlled politics before 1891. The Liberal Party set out to change that by a policy it called "populism." Richard Seddon had proclaimed the goal as early as 1884: "It is the rich and the poor; it is the wealthy and the landowners against the middle and labouring classes. That, Sir, shows the real political position of New Zealand." The Liberal strategy was to create a large class of small landowning farmers who supported Liberal ideals. The Liberal government also established the basis of the later welfare state such as old age pensions and developed a system for settling industrial disputes, which was accepted by both employers and trade unions. In 1893, it extended voting rights to women, making New Zealand the first country in the world to do so.
To obtain land for farmers, the Liberal government from 1891 to 1911 purchased of Maori land. The government also purchased from large estate holders for subdivision and closer settlement by small farmers. The Advances to Settlers Act (1894) provided low-interest mortgages, and the agriculture department disseminated information on the best farming methods. The Liberals proclaimed success in forging an egalitarian, anti-monopoly land policy. The policy built up support for the Liberal Party in rural North Island electorates. By 1903, the Liberals were so dominant that there was no longer an organized opposition in Parliament.James Belich, Paradise Reforged: A history of the New Zealanders (2001) pp. 39–46Tom Brooking, "'Busting Up' the Greatest Estate of All: Liberal Maori Land Policy, 1891–1911," New Zealand Journal of History (1992) 26#1 pp. 78–98 online |
Agrarianism | North America | North America
The United States and Canada both saw a rise of Agrarian-oriented parties in the early twentieth century as economic troubles motivated farming communities to become politically active. It has been proposed that different responses to agrarian protest largely determined the course of power generated by these newly energized rural factions. According to Sociologist Barry Eidlin:"In the United States, Democrats adopted a co-optive response to farmer and labor protest, incorporating these constituencies into the New Deal coalition. In Canada, both mainstream parties adopted a coercive response, leaving these constituencies politically excluded and available for an independent left coalition."These reactions may have helped determine the outcome of agrarian power and political associations in the US and Canada. |
Agrarianism | United States of America | United States of America |
Agrarianism | Kansas | Kansas
Economic desperation experienced by farmers across the state of Kansas in the nineteenth century spurred the creation of The People's Party in 1890, and soon-after would gain control of the governor's office in 1892. This party, consisting of a mix of Democrats, Socialists, Populists, and Fusionists, would find itself buckling from internal conflict regarding the unlimited coinage of silver. The Populists permanently lost power in 1898. |
Agrarianism | Oklahoma | Oklahoma
Oklahoma farmers considered their political activity during the early twentieth century due to the outbreak of war, depressed crop prices, and an inhibited sense of progression towards owning their own farms. Tenancy had been reportedly as high as 55% in Oklahoma by 1910. These pressures saw agrarian counties in Oklahoma supporting Socialist policies and politics, with the Socialist platform proposing a deeply agrarian-radical platform:...the platform proposed a "Renters and Farmer's Program" which was strongly agrarian radical in its insistence upon various measures to put land into "The hands of the actual tillers of the soil." Although it did not propose to nationalize privately owned land, it did offer numerous plans to enlarge the state's public domain, from which land would be rented at prevailing share rents to tenants until they had paid rent equal to the land's value. The tenant and his children would have the right of occupancy and use, but the 'title' would remind in the 'commonwealth', an arrangement that might be aptly termed 'Socialist fee simple'. They proposed to exempt from taxation all farm dwellings, animals, and improvements up to the value of $1,000. The State Board of Agriculture would encourage 'co-operative societies' of farmers to make plans f or the purchase of land, seed, tools, and for preparing and selling produce. In order to give farmers essential services at cost, the Socialists called for the creation of state banks and mortgage agencies, crop insurance, elevators, and warehouses.This agrarian-backed Socialist party would win numerous offices, causing a panic within the local Democratic party. This agrarian-Socialist movement would be inhibited by voter suppression laws aimed at reducing the participation of voters of color, as well as national wartime policies intended to disrupt political elements considered subversive. This party would peak in power in 1914. |
Agrarianism | Back-to-the-land movement | Back-to-the-land movement
Agrarianism is similar to but not identical with the back-to-the-land movement. Agrarianism concentrates on the fundamental goods of the earth, on communities of more limited economic and political scale than in modern society, and on simple living, even when the shift involves questioning the "progressive" character of some recent social and economic developments. Thus, agrarianism is not industrial farming, with its specialization on products and industrial scale.Jeffrey Carl Jacob, New Pioneers: The Back-to-the-Land Movement and the Search for a Sustainable Future (Penn State University Press. 1997) |
Agrarianism | See also | See also
Agrarian socialism
Farmer–Labor Party, USA early 20th century
Jeffersonian democracy
Labour-Farmer Party, Japan 1920s
Minnesota Farmer–Labor Party, USA early 20th century
Nordic agrarian parties
Yeoman, English farmers |
Agrarianism | References | References |
Agrarianism | Further reading | Further reading |
Agrarianism | Agrarian values | Agrarian values
Brass, Tom. Peasants, Populism and Postmodernism: The Return of the Agrarian Myth (2000)
Marx, Leo. The Machine in the Garden: Technology and the Pastoral Ideal in America (1964).
Murphy, Paul V. The Rebuke of History: The Southern Agrarians and American Conservative Thought (2000)
Parrington, Vernon. Main Currents in American Thought (1927), 3-vol online
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Agrarianism | Primary sources | Primary sources
Sorokin, Pitirim A. et al., eds. A Systematic Source Book in Rural Sociology (3 vol. 1930) vol 1 pp. 1–146 covers many major thinkers down to 1800 |
Agrarianism | Europe | Europe
Bell, John D. Peasants in Power: Alexander Stamboliski and the Bulgarian Agrarian National Union, 1899–1923(1923)
Donnelly, James S. Captain Rock: The Irish Agrarian Rebellion of 1821–1824 (2009)
Donnelly, James S. Irish Agrarian Rebellion, 1760–1800 (2006)
Gross, Feliks, ed. European Ideologies: A Survey of 20th Century Political Ideas (1948) pp. 391–481 online edition , on Russia and Bulgaria
Kubricht, Andrew Paul. "The Czech Agrarian Party, 1899–1914: a study of national and economic agitation in the Habsburg monarchy" (PhD thesis, Ohio State University Press, 1974)
Oren, Nissan. Revolution Administered: Agrarianism and Communism in Bulgaria (1973), focus is post 1945
Stefanov, Kristian. Between Ideological Loyalty and Political Adaptation: 'The Agrarian Question' in the Development of Bulgarian Social Democracy, 1891–1912, East European Politics, Societies and Cultures, Is. 4, 2023.
Roberts, Henry L. Rumania: Political Problems of an Agrarian State (1951).
North America
Goodwyn, Lawrence. The Populist Moment: A Short History of the Agrarian Revolt in America (1978), 1880s and 1890s in U.S.
Lipset, Seymour Martin. Agrarian socialism: the Coöperative Commonwealth Federation in Saskatchewan (1950), 1930s–1940s
McConnell, Grant. The decline of agrarian democracy(1953), 20th century U.S.
Mark, Irving. Agrarian conflicts in colonial New York, 1711–1775 (1940)
Robison, Dan Merritt. Bob Taylor and the agrarian revolt in Tennessee (1935)
Stine, Harold E. The agrarian revolt in South Carolina;: Ben Tillman and the Farmers' Alliance (1974)
Szatmary, David P. Shays' Rebellion: The Making of an Agrarian Insurrection (1984), 1787 in Massachusetts
Woodward, C. Vann. Tom Watson: Agrarian Rebel (1938) online edition
Global South
Handy, Jim. Revolution in the Countryside: Rural Conflict and Agrarian Reform in Guatemala, 1944–1954 (1994)
Paige, Jeffery M. Agrarian revolution: social movements and export agriculture in the underdeveloped world (1978) 435 pages excerpt and text search
Sanderson, Steven E. Agrarian populism and the Mexican state: the struggle for land in Sonora'' (1981)
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Agrarianism | External links | External links
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Agrarianism | Table of Content | Short description, Philosophy, History, Types of agrarianism, Physiocracy, Jeffersonian democracy, Agrarian socialism, Zapatismo, Maoism, Notable agrarian parties, Europe, Bulgaria, Czechoslovakia, France, Hungary, Ireland, Kazakhstan, Latvia, Lithuania, Nordic countries, Poland, Romania, Serbia, Ukraine, United Kingdom, Oceania, Australia, New Zealand, North America, United States of America, Kansas, Oklahoma, Back-to-the-land movement, See also, References, Further reading, Agrarian values, Primary sources, Europe, External links |
Atomic | wiktionary | Atomic may refer to:
Of or relating to the atom, the smallest particle of a chemical element that retains its chemical properties
Atomic physics, the study of the atom
Atomic Age, also known as the "Atomic Era"
Atomic scale, distances comparable to the dimensions of an atom
Atom (order theory), in mathematics
Atomic (cocktail), a champagne cocktail
Atomic (magazine), an Australian computing and technology magazine
Atomic Skis, an Austrian ski producer |
Atomic | Music | Music
Atomic (band), a Norwegian jazz quintet
Atomic (Lit album), 2001
Atomic (Mogwai album), 2016
Atomic, an album by Rockets, 1982
Atomic (EP), by , 2013
"Atomic" (song), by Blondie, 1979
"Atomic", a song by Tiger Army from Tiger Army III: Ghost Tigers Rise |
Atomic | See also | See also
Atom (disambiguation)
Atomicity (database systems)
Atomism, philosophy about the basic building blocks of reality
Atomic City (disambiguation)
Atomic formula, a formula without subformulas
Atomic number, the number of protons found in the nucleus of an atom
Atomic chess, a chess variant
Atomic coffee machine, a 1950s stovetop coffee machine
Atomic operation, in computer science
Atomic TV, a channel launched in 1997 in Poland
History of atomic theory
Nuclear power
Nuclear weapon
Nuclear (disambiguation) |
Atomic | Table of Content | wiktionary, Music, See also |
Angle | Short description | alt=two line bent at a point|thumb|upright=1.25|A green angle formed by two red rays on the Cartesian coordinate system
In Euclidean geometry, an angle or plane angle is the figure formed by two rays, called the sides of the angle, sharing a common endpoint, called the vertex of the angle.
Two intersecting curves may also define an angle, which is the angle of the rays lying tangent to the respective curves at their point of intersection. Angles are also formed by the intersection of two planes; these are called dihedral angles.
In any case, the resulting angle lies in a plane (spanned by the two rays or perpendicular to the line of plane-plane intersection).
The magnitude of an angle is called an angular measure or simply "angle". This measure, for an ordinary angle, is often visualized or defined using the arc of a circle centered at the vertex and lying between the sides. Two different angles may have the same measure, as in an isosceles triangle. "Angle" also denotes the angular sector, the infinite region of the plane bounded by the sides of an angle.
Angle of rotation is a measure conventionally defined as the ratio of a circular arc length to its radius, and may be a negative number; the arc is centered at the center of the rotation and delimited by any other point and its image after the rotation. |
Angle | History and etymology | History and etymology
The word angle comes from the Latin word , meaning "corner". Cognate words include the Greek () meaning "crooked, curved" and the English word "ankle". Both are connected with the Proto-Indo-European root *ank-, meaning "to bend" or "bow".
Euclid defines a plane angle as the inclination to each other, in a plane, of two lines that meet each other and do not lie straight with respect to each other. According to the Neoplatonic metaphysician Proclus, an angle must be either a quality, a quantity, or a relationship. The first concept, angle as quality, was used by Eudemus of Rhodes, who regarded an angle as a deviation from a straight line; the second, angle as quantity, by Carpus of Antioch, who regarded it as the interval or space between the intersecting lines; Euclid adopted the third: angle as a relationship.; |
Angle | Identifying angles | Identifying angles
In mathematical expressions, it is common to use Greek letters (α, β, γ, θ, φ, . . . ) as variables denoting the size of some angle (the symbol is typically not used for this purpose to avoid confusion with the constant denoted by that symbol). Lower case Roman letters (a, b, c, . . . ) are also used. In contexts where this is not confusing, an angle may be denoted by the upper case Roman letter denoting its vertex. See the figures in this article for examples.
The three defining points may also identify angles in geometric figures. For example, the angle with vertex A formed by the rays AB and AC (that is, the half-lines from point A through points B and C) is denoted or . Where there is no risk of confusion, the angle may sometimes be referred to by a single vertex alone (in this case, "angle A").
In other ways, an angle denoted as, say, might refer to any of four angles: the clockwise angle from B to C about A, the anticlockwise angle from B to C about A, the clockwise angle from C to B about A, or the anticlockwise angle from C to B about A, where the direction in which the angle is measured determines its sign (see ). However, in many geometrical situations, it is evident from the context that the positive angle less than or equal to 180 degrees is meant, and in these cases, no ambiguity arises. Otherwise, to avoid ambiguity, specific conventions may be adopted so that, for instance, always refers to the anticlockwise (positive) angle from B to C about A and the anticlockwise (positive) angle from C to B about A. |
Angle | Types{{anchor | Types |
Angle | Individual angles | Individual angles
There is some common terminology for angles, whose measure is always non-negative (see ):
An angle equal to 0° or not turned is called a zero angle.
An angle smaller than a right angle (less than 90°) is called an acute angle ("acute" meaning "sharp").
An angle equal to turn (90° or radians) is called a right angle. Two lines that form a right angle are said to be normal, orthogonal, or perpendicular.
An angle larger than a right angle and smaller than a straight angle (between 90° and 180°) is called an obtuse angle ("obtuse" meaning "blunt").
An angle equal to turn (180° or radians) is called a straight angle.
An angle larger than a straight angle but less than 1 turn (between 180° and 360°) is called a reflex angle.
An angle equal to 1 turn (360° or 2 radians) is called a full angle, complete angle, round angle or perigon.
An angle that is not a multiple of a right angle is called an oblique angle.
The names, intervals, and measuring units are shown in the table below:
Name zero angle acute angle right angle obtuse angle straight angle reflex angle perigon Unit Interval turn radian degree 0° (0, 90)° 90° (90, 180)° 180° (180, 360)° 360° gon 0g (0, 100)g 100g (100, 200)g 200g (200, 400)g 400g |
Angle | Vertical and {{vanchor | Vertical and angle pairs
thumb|150px|right|Angles A and B are a pair of vertical angles; angles C and D are a pair of vertical angles. Hatch marks are used here to show angle equality.
When two straight lines intersect at a point, four angles are formed. Pairwise, these angles are named according to their location relative to each other.
A transversal is a line that intersects a pair of (often parallel) lines and is associated with exterior angles, interior angles, alternate exterior angles, alternate interior angles, corresponding angles, and consecutive interior angles. |
Angle | Combining angle pairs | Combining angle pairs
The angle addition postulate states that if B is in the interior of angle AOC, then
I.e., the measure of the angle AOC is the sum of the measure of angle AOB and the measure of angle BOC.
Three special angle pairs involve the summation of angles:
thumb|150px|The complementary angles a and b (b is the complement of a, and a is the complement of b.) |
Angle | Polygon-related angles | Polygon-related angles
thumb|300px|right|Internal and external angles
An angle that is part of a simple polygon is called an interior angle if it lies on the inside of that simple polygon. A simple concave polygon has at least one interior angle, that is, a reflex angle. In Euclidean geometry, the measures of the interior angles of a triangle add up to radians, 180°, or turn; the measures of the interior angles of a simple convex quadrilateral add up to 2 radians, 360°, or 1 turn. In general, the measures of the interior angles of a simple convex polygon with n sides add up to (n − 2) radians, or (n − 2)180 degrees, (n − 2)2 right angles, or (n − 2) turn.
The supplement of an interior angle is called an exterior angle; that is, an interior angle and an exterior angle form a linear pair of angles. There are two exterior angles at each vertex of the polygon, each determined by extending one of the two sides of the polygon that meet at the vertex; these two angles are vertical and hence are equal. An exterior angle measures the amount of rotation one must make at a vertex to trace the polygon. If the corresponding interior angle is a reflex angle, the exterior angle should be considered negative. Even in a non-simple polygon, it may be possible to define the exterior angle. Still, one will have to pick an orientation of the plane (or surface) to decide the sign of the exterior angle measure. In Euclidean geometry, the sum of the exterior angles of a simple convex polygon, if only one of the two exterior angles is assumed at each vertex, will be one full turn (360°). The exterior angle here could be called a supplementary exterior angle. Exterior angles are commonly used in Logo Turtle programs when drawing regular polygons.
In a triangle, the bisectors of two exterior angles and the bisector of the other interior angle are concurrent (meet at a single point).Johnson, Roger A. Advanced Euclidean Geometry, Dover Publications, 2007.
In a triangle, three intersection points, each of an external angle bisector with the opposite extended side, are collinear.
In a triangle, three intersection points, two between an interior angle bisector and the opposite side, and the third between the other exterior angle bisector and the opposite side extended are collinear.
Some authors use the name exterior angle of a simple polygon to mean the explement exterior angle (not supplement!) of the interior angle. as cited in This conflicts with the above usage. |
Angle | Plane-related angles | Plane-related angles
The angle between two planes (such as two adjacent faces of a polyhedron) is called a dihedral angle. It may be defined as the acute angle between two lines normal to the planes.
The angle between a plane and an intersecting straight line is complementary to the angle between the intersecting line and the normal to the plane. |
Angle | Measuring angles{{anchor | Measuring angles
The size of a geometric angle is usually characterized by the magnitude of the smallest rotation that maps one of the rays into the other. Angles of the same size are said to be equal congruent or equal in measure.
In some contexts, such as identifying a point on a circle or describing the orientation of an object in two dimensions relative to a reference orientation, angles that differ by an exact multiple of a full turn are effectively equivalent. In other contexts, such as identifying a point on a spiral curve or describing an object's cumulative rotation in two dimensions relative to a reference orientation, angles that differ by a non-zero multiple of a full turn are not equivalent.
right|thumb|The measure of angle is .
To measure an angle θ, a circular arc centered at the vertex of the angle is drawn, e.g., with a pair of compasses. The ratio of the length s of the arc by the radius r of the circle is the number of radians in the angle:
Conventionally, in mathematics and the SI, the radian is treated as being equal to the dimensionless unit 1, thus being normally omitted.
The angle expressed by another angular unit may then be obtained by multiplying the angle by a suitable conversion constant of the form , where k is the measure of a complete turn expressed in the chosen unit (for example, for degrees or 400 grad for gradians):
The value of thus defined is independent of the size of the circle: if the length of the radius is changed, then the arc length changes in the same proportion, so the ratio s/r is unaltered. |
Angle | Units | Units
right|thumb|150 px|Definition of 1 radian
Throughout history, angles have been measured in various units. These are known as angular units, with the most contemporary units being the degree ( ° ), the radian (rad), and the gradian (grad), though many others have been used throughout history. Most units of angular measurement are defined such that one turn (i.e., the angle subtended by the circumference of a circle at its centre) is equal to n units, for some whole number n. Two exceptions are the radian (and its decimal submultiples) and the diameter part.
In the International System of Quantities, an angle is defined as a dimensionless quantity, and in particular, the radian unit is dimensionless. This convention impacts how angles are treated in dimensional analysis.
The following table lists some units used to represent angles.
Name Number in one turnIn degrees Descriptionradian≈57°17′45″The radian is determined by the circumference of a circle that is equal in length to the radius of the circle (n = 2 = 6.283...). It is the angle subtended by an arc of a circle that has the same length as the circle's radius. The symbol for radian is rad. One turn is 2 radians, and one radian is , or about 57.2958 degrees. Often, particularly in mathematical texts, one radian is assumed to equal one, resulting in the unit rad being omitted. The radian is used in virtually all mathematical work beyond simple, practical geometry due, for example, to the pleasing and "natural" properties that the trigonometric functions display when their arguments are in radians. The radian is the (derived) unit of angular measurement in the SI.degree 360 1° The degree, denoted by a small superscript circle (°), is 1/360 of a turn, so one turn is 360°. One advantage of this old sexagesimal subunit is that many angles common in simple geometry are measured as a whole number of degrees. Fractions of a degree may be written in normal decimal notation (e.g., 3.5° for three and a half degrees), but the "minute" and "second" sexagesimal subunits of the "degree–minute–second" system (discussed next) are also in use, especially for geographical coordinates and in astronomy and ballistics (n = 360) arcminute21,600 0°1′ The minute of arc (or MOA, arcminute, or just minute) is of a degree = turn. It is denoted by a single prime ( ′ ). For example, 3° 30′ is equal to 3 × 60 + 30 = 210 minutes or 3 + = 3.5 degrees. A mixed format with decimal fractions is sometimes used, e.g., 3° 5.72′ = 3 + degrees. A nautical mile was historically defined as an arcminute along a great circle of the Earth. (n = 21,600). arcsecond1,296,000 0°0′1″The second of arc (or arcsecond, or just second) is of a minute of arc and of a degree (n = 1,296,000). It is denoted by a double prime ( ″ ). For example, 3° 7′ 30″ is equal to 3 + + degrees, or 3.125 degrees. The arcsecond is the angle used to measure a parsec grad400 0°54′ The grad, also called grade, gradian, or gon. It is a decimal subunit of the quadrant. A right angle is 100 grads. A kilometre was historically defined as a centi-grad of arc along a meridian of the Earth, so the kilometer is the decimal analog to the sexagesimal nautical mile (n = 400). The grad is used mostly in triangulation and continental surveying.turn1360° The turn is the angle subtended by the circumference of a circle at its centre. A turn is equal to 2 or (tau) radians. hour angle 24 15° The astronomical hour angle is turn. As this system is amenable to measuring objects that cycle once per day (such as the relative position of stars), the sexagesimal subunits are called minute of time and second of time. These are distinct from, and 15 times larger than, minutes and seconds of arc. 1 hour = 15° = rad = quad = turn = grad. (compass) point 32 11°15′ The point or wind, used in navigation, is of a turn. 1 point = of a right angle = 11.25° = 12.5 grad. Each point is subdivided into four quarter points, so one turn equals 128. milliradian ≈0.057° The true milliradian is defined as a thousandth of a radian, which means that a rotation of one turn would equal exactly 2000π mrad (or approximately 6283.185 mrad). Almost all scope sights for firearms are calibrated to this definition. In addition, three other related definitions are used for artillery and navigation, often called a 'mil', which are approximately equal to a milliradian. Under these three other definitions, one turn makes up for exactly 6000, 6300, or 6400 mils, spanning the range from 0.05625 to 0.06 degrees (3.375 to 3.6 minutes). In comparison, the milliradian is approximately 0.05729578 degrees (3.43775 minutes). One "NATO mil" is defined as of a turn. Just like with the milliradian, each of the other definitions approximates the milliradian's useful property of subtensions, i.e. that the value of one milliradian approximately equals the angle subtended by a width of 1 meter as seen from 1 km away ( = 0.0009817... ≈ ).binary degree 2561°33′45″ The binary degree, also known as the binary radian or brad or binary angular measurement (BAM). The binary degree is used in computing so that an angle can be efficiently represented in a single byte (albeit to limited precision). Other measures of the angle used in computing may be based on dividing one whole turn into 2n equal parts for other values of n.
It is of a turn. radian2180° The multiples of radians (MUL) unit is implemented in the RPN scientific calculator WP 43S. See also: IEEE 754 recommended operationsquadrant490°One quadrant is a turn and also known as a right angle. The quadrant is the unit in Euclid's Elements. In German, the symbol ∟ has been used to denote a quadrant. 1 quad = 90° = rad = turn = 100 grad.sextant660°The sextant was the unit used by the Babylonians, The degree, minute of arc and second of arc are sexagesimal subunits of the Babylonian unit. It is straightforward to construct with ruler and compasses. It is the angle of the equilateral triangle or is turn. 1 Babylonian unit = 60° = /3 rad ≈ 1.047197551 rad. hexacontade60 6°The hexacontade is a unit used by Eratosthenes. It equals 6°, so a whole turn was divided into 60 hexacontades. pechus 144 to 180 2° to 2°30′ The pechus was a Babylonian unit equal to about 2° or °. diameter part ≈376.991 ≈0.95493° The diameter part (occasionally used in Islamic mathematics) is radian. One "diameter part" is approximately 0.95493°. There are about 376.991 diameter parts per turn. zam 224 ≈1.607° In old Arabia, a turn was subdivided into 32 Akhnam, and each akhnam was subdivided into 7 zam so that a turn is 224 zam. |
Angle | Dimensional analysis | Dimensional analysis |
Angle | Signed angles <span class="anchor" id="Sign"></span><span class="anchor" id="Positive and negative angles"></span> | Signed angles
right|thumb|Measuring from the x-axis, angles on the unit circle count as positive in the counterclockwise direction, and negative in the clockwise direction.
It is frequently helpful to impose a convention that allows positive and negative angular values to represent orientations and/or rotations in opposite directions or "sense" relative to some reference.
In a two-dimensional Cartesian coordinate system, an angle is typically defined by its two sides, with its vertex at the origin. The initial side is on the positive x-axis, while the other side or terminal side is defined by the measure from the initial side in radians, degrees, or turns, with positive angles representing rotations toward the positive y-axis and negative angles representing rotations toward the negative y-axis. When Cartesian coordinates are represented by standard position, defined by the x-axis rightward and the y-axis upward, positive rotations are anticlockwise, and negative cycles are clockwise.
In many contexts, an angle of −θ is effectively equivalent to an angle of "one full turn minus θ". For example, an orientation represented as −45° is effectively equal to an orientation defined as 360° − 45° or 315°. Although the final position is the same, a physical rotation (movement) of −45° is not the same as a rotation of 315° (for example, the rotation of a person holding a broom resting on a dusty floor would leave visually different traces of swept regions on the floor).
In three-dimensional geometry, "clockwise" and "anticlockwise" have no absolute meaning, so the direction of positive and negative angles must be defined in terms of an orientation, which is typically determined by a normal vector passing through the angle's vertex and perpendicular to the plane in which the rays of the angle lie.
In navigation, bearings or azimuth are measured relative to north. By convention, viewed from above, bearing angles are positive clockwise, so a bearing of 45° corresponds to a north-east orientation. Negative bearings are not used in navigation, so a north-west orientation corresponds to a bearing of 315°. |
Angle | Equivalent angles | Equivalent angles
Angles that have the same measure (i.e., the same magnitude) are said to be equal or congruent. An angle is defined by its measure and is not dependent upon the lengths of the sides of the angle (e.g., all right angles are equal in measure).
Two angles that share terminal sides, but differ in size by an integer multiple of a turn, are called coterminal angles.
The reference angle (sometimes called related angle) for any angle θ in standard position is the positive acute angle between the terminal side of θ and the x-axis (positive or negative). Procedurally, the magnitude of the reference angle for a given angle may determined by taking the angle's magnitude modulo turn, 180°, or radians, then stopping if the angle is acute, otherwise taking the supplementary angle, 180° minus the reduced magnitude. For example, an angle of 30 degrees is already a reference angle, and an angle of 150 degrees also has a reference angle of 30 degrees (180° − 150°). Angles of 210° and 510° correspond to a reference angle of 30 degrees as well (210° mod 180° = 30°, 510° mod 180° = 150° whose supplementary angle is 30°). |
Angle | Related quantities | Related quantities
For an angular unit, it is definitional that the angle addition postulate holds. Some quantities related to angles where the angle addition postulate does not hold include:
The slope or gradient is equal to the tangent of the angle; a gradient is often expressed as a percentage. For very small values (less than 5%), the slope of a line is approximately the measure in radians of its angle with the horizontal direction.
The spread between two lines is defined in rational geometry as the square of the sine of the angle between the lines. As the sine of an angle and the sine of its supplementary angle are the same, any angle of rotation that maps one of the lines into the other leads to the same value for the spread between the lines.
Although done rarely, one can report the direct results of trigonometric functions, such as the sine of the angle. |
Angle | Angles between curves | Angles between curves
thumb|right|The angle between the two curves at P is defined as the angle between the tangents A and B at P.
The angle between a line and a curve (mixed angle) or between two intersecting curves (curvilinear angle) is defined to be the angle between the tangents at the point of intersection. Various names (now rarely, if ever, used) have been given to particular cases:—amphicyrtic (Gr. , on both sides, κυρτός, convex) or cissoidal (Gr. κισσός, ivy), biconvex; xystroidal or sistroidal (Gr. ξυστρίς, a tool for scraping), concavo-convex; amphicoelic (Gr. κοίλη, a hollow) or angulus lunularis, biconcave.; |
Angle | Bisecting and trisecting angles | Bisecting and trisecting angles
The ancient Greek mathematicians knew how to bisect an angle (divide it into two angles of equal measure) using only a compass and straightedge but could only trisect certain angles. In 1837, Pierre Wantzel showed that this construction could not be performed for most angles. |
Angle | Dot product and generalisations{{anchor | Dot product and generalisations
In the Euclidean space, the angle θ between two Euclidean vectors u and v is related to their dot product and their lengths by the formula
This formula supplies an easy method to find the angle between two planes (or curved surfaces) from their normal vectors and between skew lines from their vector equations. |
Angle | Inner product | Inner product
To define angles in an abstract real inner product space, we replace the Euclidean dot product ( · ) by the inner product , i.e.
In a complex inner product space, the expression for the cosine above may give non-real values, so it is replaced with
or, more commonly, using the absolute value, with
The latter definition ignores the direction of the vectors. It thus describes the angle between one-dimensional subspaces and spanned by the vectors and correspondingly. |
Angle | Angles between subspaces | Angles between subspaces
The definition of the angle between one-dimensional subspaces and given by
in a Hilbert space can be extended to subspaces of finite dimensions. Given two subspaces , with , this leads to a definition of angles called canonical or principal angles between subspaces. |
Angle | Angles in Riemannian geometry | Angles in Riemannian geometry
In Riemannian geometry, the metric tensor is used to define the angle between two tangents. Where U and V are tangent vectors and gij are the components of the metric tensor G, |
Angle | Hyperbolic angle | Hyperbolic angle
A hyperbolic angle is an argument of a hyperbolic function just as the circular angle is the argument of a circular function. The comparison can be visualized as the size of the openings of a hyperbolic sector and a circular sector since the areas of these sectors correspond to the angle magnitudes in each case.Robert Baldwin Hayward (1892) The Algebra of Coplanar Vectors and Trigonometry, chapter six Unlike the circular angle, the hyperbolic angle is unbounded. When the circular and hyperbolic functions are viewed as infinite series in their angle argument, the circular ones are just alternating series forms of the hyperbolic functions. This comparison of the two series corresponding to functions of angles was described by Leonhard Euler in Introduction to the Analysis of the Infinite (1748). |
Angle | Angles in geography and astronomy | Angles in geography and astronomy
In geography, the location of any point on the Earth can be identified using a geographic coordinate system. This system specifies the latitude and longitude of any location in terms of angles subtended at the center of the Earth, using the equator and (usually) the Greenwich meridian as references.
In astronomy, a given point on the celestial sphere (that is, the apparent position of an astronomical object) can be identified using any of several astronomical coordinate systems, where the references vary according to the particular system. Astronomers measure the angular separation of two stars by imagining two lines through the center of the Earth, each intersecting one of the stars. The angle between those lines and the angular separation between the two stars can be measured.
In both geography and astronomy, a sighting direction can be specified in terms of a vertical angle such as altitude /elevation with respect to the horizon as well as the azimuth with respect to north.
Astronomers also measure objects' apparent size as an angular diameter. For example, the full moon has an angular diameter of approximately 0.5° when viewed from Earth. One could say, "The Moon's diameter subtends an angle of half a degree." The small-angle formula can convert such an angular measurement into a distance/size ratio.
Other astronomical approximations include:
0.5° is the approximate diameter of the Sun and of the Moon as viewed from Earth.
1° is the approximate width of the little finger at arm's length.
10° is the approximate width of a closed fist at arm's length.
20° is the approximate width of a handspan at arm's length.
These measurements depend on the individual subject, and the above should be treated as rough rule of thumb approximations only.
In astronomy, right ascension and declination are usually measured in angular units, expressed in terms of time, based on a 24-hour day.
Unit Symbol Degrees Radians Turns Other Hour h 15° rad turn Minute m 0°15′ rad turn hour Second s 0°0′15″ rad turn minute |
Angle | See also | See also
Angle measuring instrument
Angles between flats
Angular statistics (mean, standard deviation)
Angle bisector
Angular acceleration
Angular diameter
Angular velocity
Argument (complex analysis)
Astrological aspect
Central angle
Clock angle problem
Decimal degrees
Dihedral angle
Exterior angle theorem
Golden angle
Great circle distance
Horn angle
Inscribed angle
Irrational angle
Phase (waves)
Protractor
Solid angle
Spherical angle
Subtended angle
Tangential angle
Transcendent angle
Trisection
Zenith angle |
Angle | Notes | Notes |
Angle | References | References |
Angle | Bibliography | Bibliography
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Angle | External links | External links
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Angle | Table of Content | Short description, History and etymology, Identifying angles, Types{{anchor, Individual angles, Vertical and {{vanchor, Combining angle pairs, Polygon-related angles, Plane-related angles, Measuring angles{{anchor, Units, Dimensional analysis, Signed angles <span class="anchor" id="Sign"></span><span class="anchor" id="Positive and negative angles"></span>, Equivalent angles, Related quantities, Angles between curves, Bisecting and trisecting angles, Dot product and generalisations{{anchor, Inner product, Angles between subspaces, Angles in Riemannian geometry, Hyperbolic angle, Angles in geography and astronomy, See also, Notes, References, Bibliography, External links |
Asa | wiktionary | Asa may refer to: |
Asa | People and fictional characters | People and fictional characters
Asa (given name), a given name, including a list of people and fictional characters so named
Asa people, an ethnic group based in Tanzania
Aṣa, Nigerian-French singer, songwriter, and recording artist Bukola Elemide (born 1982)
Asa (rapper), Finnish rapper Matti Salo (born 1980) |
Asa | Biblical and mythological figures | Biblical and mythological figures
Asa of Judah, third king of the Kingdom of Judah and the fifth king of the House of David
Ása or Æsir, Norse gods |
Asa | Places | Places
Asa, Hardoi Uttar Pradesh, India, a village
Asu, South Khorasan, Iran, also spelled Asa, a village
Asa, Kwara State, Nigeria, a local government area
Asa River (Japan), a tributary of the Tama River in Tokyo, Japan
Asa (Kazakhstan), a river
Asa River (Venezuela), a river in Venezuela |
Asa | Other uses | Other uses
Acrylonitrile styrene acrylate, acrylic styrene acrylonitrile, an amorphous thermoplastic
Asa (album), the sixth studio album by the German Viking metal band Falkenbach
Asa (raga), a peculiar musical raga in Gurmat Sangeet tradition
ASA carriage control characters, simple printing command characters used to control the movement of paper through line printers
Asa language, spoken by the Asa people of Tanzania
Asa Station, a railway station in San'yō-Onoda, Yamaguchi, Japan
Asa (railway station), Jambyl Region, Kazakhstan
Naboot, also called asa, a quarterstaff constructed of palm wood or rattan
Asha, romanized as aṣ̌a, a Zoroastrian concept
"Asa", a song by Kitt Wakeley featuring Starr Parodi from An Adoption Story, 2022
“Asa”, 2024 single by Snazzy the Optimist |
Asa | See also | See also
ASA (disambiguation)
Åsa (disambiguation)
Aasa (disambiguation)
Asia (disambiguation)
Aza (disambiguation) |
Asa | Table of Content | wiktionary, People and fictional characters, Biblical and mythological figures, Places, Other uses, See also |
Acoustics | short description | thumb|alt=Lindsay's Wheel of acoustics|upright=1.75|Lindsay's Wheel of Acoustics, which shows fields within acoustics
Acoustics is a branch of physics that deals with the study of mechanical waves in gases, liquids, and solids including topics such as vibration, sound, ultrasound and infrasound. A scientist who works in the field of acoustics is an acoustician while someone working in the field of acoustics technology may be called an acoustical engineer. The application of acoustics is present in almost all aspects of modern society with the most obvious being the audio and noise control industries.
Hearing is one of the most crucial means of survival in the animal world and speech is one of the most distinctive characteristics of human development and culture. Accordingly, the science of acoustics spreads across many facets of human society—music, medicine, architecture, industrial production, warfare and more. Likewise, animal species such as songbirds and frogs use sound and hearing as a key element of mating rituals or for marking territories. Art, craft, science and technology have provoked one another to advance the whole, as in many other fields of knowledge. Robert Bruce Lindsay's "Wheel of Acoustics" is a well-accepted overview of the various fields in acoustics. |
Acoustics | History | History |
Acoustics | Etymology | Etymology
The word "acoustic" is derived from the Greek word ἀκουστικός (akoustikos), meaning "of or for hearing, ready to hear"Akoustikos Henry George Liddell, Robert Scott, A Greek-English Lexicon, at Perseus and that from ἀκουστός (akoustos), "heard, audible",Akoustos Henry George Liddell, Robert Scott, A Greek-English Lexicon, at Perseus which in turn derives from the verb ἀκούω(akouo), "I hear".Akouo Henry George Liddell, Robert Scott, A Greek-English Lexicon, at Perseus
The Latin synonym is "sonic", after which the term sonics used to be a synonym for acoustics and later a branch of acoustics. Frequencies above and below the audible range are called "ultrasonic" and "infrasonic", respectively. |
Acoustics | Early research in acoustics | Early research in acoustics
thumb|The fundamental and the first 6 overtones of a vibrating string. The earliest records of the study of this phenomenon are attributed to the philosopher Pythagoras in the 6th century BC.
In the 6th century BC, the ancient Greek philosopher Pythagoras wanted to know why some combinations of musical sounds seemed more beautiful than others, and he found answers in terms of numerical ratios representing the harmonic overtone series on a string. He is reputed to have observed that when the lengths of vibrating strings are expressible as ratios of integers (e.g. 2 to 3, 3 to 4), the tones produced will be harmonious, and the smaller the integers the more harmonious the sounds. For example, a string of a certain length would sound particularly harmonious with a string of twice the length (other factors being equal). In modern parlance, if a string sounds the note C when plucked, a string twice as long will sound a C an octave lower. In one system of musical tuning, the tones in between are then given by 16:9 for D, 8:5 for E, 3:2 for F, 4:3 for G, 6:5 for A, and 16:15 for B, in ascending order.C. Boyer and U. Merzbach. A History of Mathematics. Wiley 1991, p. 55.
Aristotle (384–322 BC) understood that sound consisted of compressions and rarefactions of air which "falls upon and strikes the air which is next to it...", (quoting from Aristotle's Treatise on Sound and Hearing) a very good expression of the nature of wave motion. On Things Heard, generally ascribed to Strato of Lampsacus, states that the pitch is related to the frequency of vibrations of the air and to the speed of sound.
In about 20 BC, the Roman architect and engineer Vitruvius wrote a treatise on the acoustic properties of theaters including discussion of interference, echoes, and reverberation—the beginnings of architectural acoustics.ACOUSTICS, Bruce Lindsay, Dowden – Hutchingon Books Publishers, Chapter 3 In Book V of his (The Ten Books of Architecture) Vitruvius describes sound as a wave comparable to a water wave extended to three dimensions, which, when interrupted by obstructions, would flow back and break up following waves. He described the ascending seats in ancient theaters as designed to prevent this deterioration of sound and also recommended bronze vessels (echea) of appropriate sizes be placed in theaters to resonate with the fourth, fifth and so on, up to the double octave, in order to resonate with the more desirable, harmonious notes.Vitruvius Pollio, Vitruvius, the Ten Books on Architecture (1914) Tr. Morris Hickey Morgan BookV, Sec.6–8Vitruvius article @WikiquoteErnst Mach, Introduction to The Science of Mechanics: A Critical and Historical Account of its Development (1893, 1960) Tr. Thomas J. McCormack
During the Islamic golden age, Abū Rayhān al-Bīrūnī (973–1048) is believed to have postulated that the speed of sound was much slower than the speed of light.
thumb|left|Principles of acoustics have been applied since ancient times: a Roman theatre in the city of Amman
The physical understanding of acoustical processes advanced rapidly during and after the Scientific Revolution. Mainly Galileo Galilei (1564–1642) but also Marin Mersenne (1588–1648), independently, discovered the complete laws of vibrating strings (completing what Pythagoras and Pythagoreans had started 2000 years earlier). Galileo wrote "Waves are produced by the vibrations of a sonorous body, which spread through the air, bringing to the tympanum of the ear a stimulus which the mind interprets as sound", a remarkable statement that points to the beginnings of physiological and psychological acoustics. Experimental measurements of the speed of sound in air were carried out successfully between 1630 and 1680 by a number of investigators, prominently Mersenne. Inspired by Mersenne's Harmonie universelle (Universal Harmony) or 1634, the Rome-based Jesuit scholar Athanasius Kircher undertook research in acoustics.P. Findlen, Athanasius Kircher: The Last Man who Knew Everything, Routledge, 2004, p. 8 and p. 23. Kircher published two major books on acoustics: the Musurgia universalis (Universal Music-Making) in 1650Athanasius Kircher, Musurgia universalis sive Ars magna consoni et dissoni, Romae, typis Ludovici Grignani, 1650 and the Phonurgia nova (New Sound-Making) in 1673.Athanasius Kircher, Phonurgia nova, sive conjugium mechanico-physicum artis & natvrae paranympha phonosophia concinnatum, Campidonae: Rudolphum Dreherr, 1673. Meanwhile, Newton (1642–1727) derived the relationship for wave velocity in solids, a cornerstone of physical acoustics (Principia, 1687). |
Acoustics | Age of Enlightenment and onward | Age of Enlightenment and onward
Substantial progress in acoustics, resting on firmer mathematical and physical concepts, was made during the eighteenth century by Euler (1707–1783), Lagrange (1736–1813), and d'Alembert (1717–1783). During this era, continuum physics, or field theory, began to receive a definite mathematical structure. The wave equation emerged in a number of contexts, including the propagation of sound in air.
In the nineteenth century the major figures of mathematical acoustics were Helmholtz in Germany, who consolidated the field of physiological acoustics, and Lord Rayleigh in England, who combined the previous knowledge with his own copious contributions to the field in his monumental work The Theory of Sound (1877). Also in the 19th century, Wheatstone, Ohm, and Henry developed the analogy between electricity and acoustics.
The twentieth century saw a burgeoning of technological applications of the large body of scientific knowledge that was by then in place. The first such application was Sabine's groundbreaking work in architectural acoustics, and many others followed. Underwater acoustics was used for detecting submarines in the first World War. Sound recording and the telephone played important roles in a global transformation of society. Sound measurement and analysis reached new levels of accuracy and sophistication through the use of electronics and computing. The ultrasonic frequency range enabled wholly new kinds of application in medicine and industry. New kinds of transducers (generators and receivers of acoustic energy) were invented and put to use. |