title: Columbian exchange

text: The first manifestation of the Columbian exchange may have been the spread of syphilis from the native people of the Caribbean Sea to Europe. The history of syphilis has been well-studied, but the origin of the disease remains a subject of debate. There are two primary hypotheses: one proposes that syphilis was carried to Europe from the Americas by the crew of Christopher Columbus in the early 1490s, while the other proposes that syphilis previously existed in Europe but went unrecognized. The first written descriptions of the disease in the Old World came in 1493. The first large outbreak of syphilis in Europe occurred in 1494–1495 among the army of Charles VIII during its invasion of Naples. Many of the crew members who had served with Columbus had joined this army. After the victory, Charles's largely mercenary army returned to their respective homes, thereby spreading "the Great Pox" across Europe and killing up to five million people.


title: Columbian exchange

text: The Columbian exchange of diseases in the other direction was by far deadlier. The peoples of the Americas had had no contact to European and African diseases and little or no immunity. An epidemic of swine influenza beginning in 1493 killed many of the Taino people inhabiting Caribbean islands. The pre-contact population of the island of Hispanola was probably at least 500,000, but by 1526, fewer than 500 were still alive. Spanish exploitation was part of the cause of the near-extinction of the native people. In 1518, smallpox was first recorded in the Americas and became the deadliest imported European disease. Forty percent of the 200,000 people living in the Aztec capital of Tenochtitlan, later Mexico City, are estimated to have died of smallpox in 1520 during the war of the Aztecs with conquistador Hernán Cortés. Epidemics, possibly of smallpox and spread from Central America, decimated the population of the Inca Empire a few years before the arrival of the Spanish. The ravages of European diseases and Spanish exploitation reduced the Mexican population from an estimated 20 million to barely more than a million in the 16th century. The indigenous population of Peru decreased from about 9 million in the pre-Columbian era to 600,000 in 1620. Scholars Nunn and Qian estimate that 80–95 percent of the Native American population died in epidemics within the first 100–150 years following 1492. The deadliest Old World diseases in the Americas were smallpox, measles, whooping cough, chicken pox, bubonic plague, typhus, and malaria.


title: Columbian exchange

text: The Atlantic slave trade consisted of the involuntary immigration of 11.7 million Africans, primarily from West Africa, to the Americas between the 16th and 19th centuries, far outnumbering the about 3.4 million Europeans who migrated, most voluntarily, to the New World between 1492 and 1840. The prevalence of African slaves in the New World was related to the demographic decline of New World peoples and the need of European colonists for labor. The Africans had greater immunities to Old World diseases than the New World peoples, and were less likely to die from disease. The journey of African slaves from Africa to America is commonly known as the "middle passage".


title: Columbian exchange

text: Enslaved Africans helped shape an emerging African-American culture in the New World. They participated in both skilled and unskilled labor. Their descendants gradually developed an ethnicity that drew from the numerous African tribes as well as European nationalities. The descendants of African slaves make up a majority of the population in some Caribbean countries, notably Haiti and Jamaica, and a sizeable minority in most American countries.


title: Columbian exchange

text: A movement for the abolition of slavery, known as abolitionism, developed in Europe and the Americas during the 18th century. The efforts of abolitionists eventually led to the abolition of slavery (the British Empire in 1833, the United States in 1865, and Brazil in 1888).


title: Columbian exchange

text: The New World produced 80 percent or more of the world's silver in the 16th and 17th centuries, most of it at Potosí in Bolivia, but also in Mexico. The founding of the city of Manila in the Philippines in 1571 for the purpose of facilitating trade in New World silver with China for silk, porcelain, and other luxury products has been called by scholars the "origin of world trade." China was the world's largest economy and in the 1570s adopted silver (which it did not produce in any quantity) as its medium of exchange. China had little interest in buying foreign products so trade consisted of large quantities of silver coming into China to pay for the Chinese products that foreign countries desired. Silver made it to Manila either through Europe and by ship around the Cape of Good Hope or across the Pacific Ocean in Spanish galleons from the Mexican port of Acapulco. From Manila the silver was transported onward to China on Portuguese and later Dutch ships. Silver was also smuggled from Potosi to Buenos Aires, Argentina to pay slavers for African slaves imported into the New World.


title: Columbian exchange

text: The enormous quantities of silver imported into Spain and China created vast wealth but also caused inflation and the value of silver to decline. In 16th century China, six ounces of silver was equal to the value of one ounce of gold. In 1635, it took 13 ounces of silver to equal in value one ounce of gold. Taxes in both countries were assessed in the weight of silver, not its value. The shortage of revenue due to the decline in the value of silver may have contributed indirectly to the fall of the Ming dynasty in 1644. Likewise, silver from the Americas financed Spain's attempt to conquer other countries in Europe, and the decline in the value of silver left Spain faltering in the maintenance of its world-wide empire and retreating from its aggressive policies in Europe after 1650.


title: Columbian exchange

text: Although large-scale use of wheels did not occur in the Americas prior to European contact, numerous small wheeled artifacts, identified as children's toys, have been found in Mexican archeological sites, some dating to approximately 1500 BCE. Some argue that the primary obstacle to large-scale development of the wheel in the Americas was the absence of domesticated large animals that could be used to pull wheeled carriages. The closest relative of cattle present in Americas in pre-Columbian times, the American bison, is difficult to domesticate and was never domesticated by Native Americans; several horse species existed until about 12,000 years ago, but ultimately became extinct. The only large animal that was domesticated in the Western hemisphere, the llama, a pack animal, was not physically suited to use as a draft animal to pull wheeled vehicles, and use of the llama did not spread far beyond the Andes by the time of the arrival of Europeans.


title: Columbian exchange

text: On the other hand, Mesoamericans never developed the wheelbarrow, the potter's wheel, nor any other practical object with a wheel or wheels. Although present in a number of toys, very similar to those found throughout the world and still made for children today ("pull toys"), the wheel was never put into practical use in Mesoamerica before the 16th century. Possibly the closest New World civilizations came to the utilitarian wheel is the spindle whorl, and some scholars believe that the Mayan toys were originally made with spindle whorls and spindle sticks as "wheels" and "axes".


title: Columbian exchange

text: Because of the new trading resulting from the Columbian exchange, several plants native to the Americas have spread around the world, including potatoes, maize, tomatoes, and tobacco. Before 1500, potatoes were not grown outside of South America. By the 18th century, they were cultivated and consumed widely in Europe and had become important crops in both India and North America. Potatoes eventually became an important staple of the diet in much of Europe, contributing to an estimated 25% of the population growth in Afro-Eurasia between 1700 and 1900. Many European rulers, including Frederick the Great of Prussia and Catherine the Great of Russia, encouraged the cultivation of the potato.


title: Columbian exchange

text: Maize and cassava, introduced by the Portuguese from South America in the 16th century, gradually replaced sorghum and millet as Africa's most important food crops. Spanish colonizers of the 16th-century introduced new staple crops to Asia from the Americas, including maize and sweet potatoes, and thereby contributed to population growth in Asia. On a larger scale, the introduction of potatoes and maize to the Old World "resulted in caloric and nutritional improvements over previously existing staples" throughout the Eurasian landmass, enabling more varied and abundant food production.


title: Columbian exchange

text: Tomatoes, which came to Europe from the New World via Spain, were initially prized in Italy mainly for their ornamental value. But starting in the 19th century, tomato sauces became typical of Neapolitan cuisine and, ultimately, Italian cuisine in general. Coffee (introduced in the Americas circa 1720) from Africa and the Middle East and sugarcane (introduced from the Indian subcontinent) from the Spanish West Indies became the main export commodity crops of extensive Latin American plantations. Introduced to India by the Portuguese, chili and potatoes from South America have become an integral part of their cuisine.


title: Columbian exchange

text: Because crops traveled but often their endemic fungi did not, for a limited time yields were higher in their new lands. Dark & Gent 2001 term this the "". However, as globalization has continued the "Columbian Exchange of pathogens" has continued and crops have declined back toward their endemic yields the honeymoon is ending.


title: Columbian exchange

text: Rice was another crop that became widely cultivated during the Columbian exchange. As the demand in the New World grew, so did the knowledge of how to cultivate it. The two primary species used were "Oryza glaberrima" and "Oryza sativa", originating from West Africa and Southeast Asia, respectively. European planters in the New World relied upon the skills of African slaves to cultivate both species. Georgia, South Carolina, Cuba and Puerto Rico were major centers of rice production during the colonial era. Enslaved Africans brought their knowledge of water control, milling, winnowing, and other agrarian practices to the fields. This widespread knowledge among African slaves eventually led to rice becoming a staple dietary item in the New World.


title: Columbian exchange

text: Citrus fruits and grapes were brought to the Americas from the Mediterranean. At first planters struggled to adapt these crops to the climates in the New World, but by the late 19th century they were cultivated more consistently.


title: Columbian exchange

text: Bananas were introduced into the Americas in the 16th century by Portuguese sailors who came across the fruits in West Africa, while engaged in commercial ventures and the slave trade. Bananas were consumed in minimal amounts in the Americas as late as the 1880s. The U.S. did not see major increases in banana consumption until large plantations were established in the Caribbean.


title: Columbian exchange

text: It took three centuries after their introduction in Europe for tomatoes to become a widely accepted food item. Tobacco, potatoes, chili peppers, tomatillos, and tomatoes are all members of the nightshade family. Similar to some European nightshade varieties, tomatoes and potatoes can be harmful or even lethal if the wrong part of the plant is consumed in excess. Physicians in the 16th century had good reason to suspect that this native Mexican fruit was poisonous; they suspected it of generating "melancholic humours".


title: Columbian exchange

text: In 1544, Pietro Andrea Mattioli, a Tuscan physician and botanist, suggested that tomatoes might be edible, but no record exists of anyone consuming them at this time. However, in 1592 the head gardener at the botanical garden of Aranjuez near Madrid, under the patronage of Philip II of Spain, wrote, "it is said [tomatoes] are good for sauces". In spite of these comments, tomatoes remained exotic plants grown for ornamental purposes, but rarely for culinary use. On October 31, 1548, the tomato was given its first name anywhere in Europe when a house steward of Cosimo I de' Medici, Duke of Florence, wrote to the De' Medici's private secretary that the basket of "pomi d'oro" "had arrived safely". At this time, the label "pomi d'oro" was also used to refer to figs, melons, and citrus fruits in treatises by scientists. In the early years, tomatoes were mainly grown as ornamentals in Italy. For example, the Florentine aristocrat Giovan Vettorio Soderini wrote that they "were to be sought only for their beauty" and were grown only in gardens or flower beds. Tomatoes were grown in elite town and country gardens in the fifty years or so following their arrival in Europe, and were only occasionally depicted in works of art. The practice of using tomato sauce with pasta developed only in the late nineteenth century. Today around of tomatoes are cultivated in Italy.


title: Columbian exchange

text: Initially at least, the Columbian exchange of animals largely went in one direction, from Europe to the New World, as the Eurasian regions had domesticated many more animals. Horses, donkeys, mules, pigs, cattle, sheep, goats, chickens, large dogs, cats, and bees were rapidly adopted by native peoples for transport, food, and other uses. One of the first European exports to the Americas, the horse, changed the lives of many Native American tribes. The mountain tribes shifted to a nomadic lifestyle, based on hunting bison on horseback. They largely gave up settled agriculture. Horse culture was adopted gradually by Great Plains Indians. The existing Plains tribes expanded their territories with horses, and the animals were considered so valuable that horse herds became a measure of wealth. While mesoamerican peoples (Mayas in particular) already practiced apiculture, producing wax and honey from a variety of bees (such as "Melipona" or "Trigona"), European bees ("Apis mellifera")—more productive, delivering a honey with less water content and allowing for an easier extraction from beehives—were introduced in New Spain, becoming an important part of farming production.


title: Columbian exchange

text: The effects of the introduction of European livestock on the environments and peoples of the New World were not always positive. In the Caribbean, the proliferation of European animals consumed native fauna and undergrowth, changing habitat. If free ranging, the animals often damaged "conucos," plots managed by indigenous peoples for subsistence.


title: Columbian exchange

text: The Mapuche of Araucanía were fast to adopt the horse from the Spanish, and improve their military capabilities as they fought the Arauco War against Spanish colonizers. Until the arrival of the Spanish, the Mapuches had largely maintained chilihueques (llamas) as livestock. The Spanish introduction of sheep caused some competition between the two domesticated species. Anecdotal evidence of the mid-17th century show that by then both species coexisted but that the sheep far outnumbered the llamas. The decline of llamas reached a point in the late 18th century when only the Mapuche from Mariquina and Huequén next to Angol raised the animal. In the Chiloé Archipelago the introduction of pigs by the Spanish proved a success. They could feed on the abundant shellfish and algae exposed by the large tides.


title: Columbian exchange

text: In the other direction, the turkey, guinea pig, and Muscovy duck were New World animals that were transferred to Europe.


title: Columbian exchange

text: European exploration of tropical areas was aided by the New World discovery of quinine, the first effective treatment for malaria. Europeans suffered from this disease, but some indigenous populations had developed at least partial resistance to it. In Africa, resistance to malaria has been associated with other genetic changes among sub-Saharan Africans and their descendants, which can cause sickle-cell disease. The resistance of sub-Saharan Africans to malaria in the southern United States and the Caribbean contributed greatly to the specific character of the Africa-sourced slavery in those regions.


title: Columbian exchange

text: Similarly, yellow fever is thought to have been brought to the Americas from Africa via the Atlantic slave trade. Because it was endemic in Africa, many people there had acquired immunity. Europeans suffered higher rates of death than did African-descended persons when exposed to yellow fever in Africa and the Americas, where numerous epidemics swept the colonies beginning in the 17th century and continuing into the late 19th century. The disease caused widespread fatalities in the Caribbean during the heyday of slave-based sugar plantation. The replacement of native forests by sugar plantations and factories facilitated its spread in the tropical area by reducing the number of potential natural mosquito predators.The means of yellow fever transmission was unknown until 1881, when Carlos Finlay suggested that the disease was transmitted through mosquitoes, now known to be female mosquitoes of the species "Aedes aegypti".


title: Columbian exchange

text: One of the results of the movement of people between New and Old Worlds were cultural exchanges. For example, in the article "The Myth of Early Globalization: The Atlantic Economy, 1500–1800", Pieter Emmer makes the point that "from 1500 onward, a 'clash of cultures' had begun in the Atlantic". This clash of culture involved the transfer of European values to indigenous cultures. As an example, the emergence of the concept of private property in regions where property was often viewed as communal, concepts of monogamy (although many indigenous peoples were already monogamous), the role of women and children in the social system, and different concepts of labor, including slavery, although slavery was already a practice among many indigenous peoples and was widely practiced or introduced by Europeans into the Americas. Another example included the European abhorrence of human sacrifice, a religious practice among some indigenous populations.


title: Columbian exchange

text: During the initial stages of European colonization of the Americas, Europeans encountered fence-less lands. They believed that the land was unimproved and available for their taking, as they sought economic opportunity and homesteads. However, when European settlers arrived in Virginia, they encountered a fully established indigenous people, the Powhatan. The Powhatan farmers in Virginia scattered their farm plots within larger cleared areas. These larger cleared areas were a communal place for growing useful plants. As the Europeans viewed fences as hallmarks of civilization, they set about transforming "the land into something more suitable for themselves".


title: Columbian exchange

text: Tobacco was a New World agricultural product, originally a luxury good spread as part of the Columbian exchange. As is discussed in regard to the trans-Atlantic slave trade, the tobacco trade increased demand for free labor and spread tobacco worldwide. In discussing the widespread uses of tobacco, the Spanish physician Nicolas Monardes (1493–1588) noted that "The black people that have gone from these parts to the Indies, have taken up the same manner and use of tobacco that the Indians have". As Europeans traveled to other parts of the world, they took with them the practices related to tobacco. Demand for tobacco grew in the course of these cultural exchanges among peoples.


title: Columbian exchange

text: One of the most clearly notable areas of cultural clash and exchange was that of religion, often the lead point of cultural conversion. In the Spanish and Portuguese dominions, the spread of Catholicism, steeped in a European values system, was a major objective of colonization. Europeans often pursued it via explicit policies of suppression of indigenous languages, cultures and religions. In British America, Protestant missionaries converted many members of indigenous tribes to Protestantism. The French colonies had a more outright religious mandate, as some of the early explorers, such as Jacques Marquette, were also Catholic priests. In time, and given the European technological and immunological superiority which aided and secured their dominance, indigenous religions declined in the centuries following the European settlement of the Americas.


title: Columbian exchange

text: While Mapuche people did adopt the horse, sheep, and wheat, the over-all scant adoption of Spanish technology by Mapuche has been characterized as a means of cultural resistance.


title: Columbian exchange

text: According to Caroline Dodds Pennock, in Atlantic history indigenous people are often seen as static recipients of transatlantic encounters. But thousands of Native Americans crossed the ocean during the sixteenth century, some by choice.


title: Columbian exchange

text: Plants that arrived by land, sea, or air in the times before 1492 are called archaeophytes, and plants introduced to Europe after those times are called neophytes. Invasive species of plants and pathogens also were introduced by chance, including such weeds as tumbleweeds ("Salsola" spp.) and wild oats ("Avena fatua"). Some plants introduced intentionally, such as the kudzu vine introduced in 1894 from Japan to the United States to help control soil erosion, have since been found to be invasive pests in the new environment.


title: Columbian exchange

text: Fungi have also been transported, such as the one responsible for Dutch elm disease, killing American elms in North American forests and cities, where many had been planted as street trees. Some of the invasive species have become serious ecosystem and economic problems after establishing in the New World environments. A beneficial, although probably unintentional, introduction is "Saccharomyces eubayanus", the yeast responsible for lager beer now thought to have originated in Patagonia. Others have crossed the Atlantic to Europe and have changed the course of history. In the 1840s, "Phytophthora infestans" crossed the oceans, damaging the potato crop in several European nations. In Ireland, the potato crop was totally destroyed; the Great Famine of Ireland caused millions to starve to death or emigrate.


title: Columbian exchange

text: In addition to these, many animals were introduced to new habitats on the other side of the world either accidentally or incidentally. These include such animals as brown rats, earthworms (apparently absent from parts of the pre-Columbian New World), and zebra mussels, which arrived on ships. Escaped and feral populations of non-indigenous animals have thrived in both the Old and New Worlds, often negatively impacting or displacing native species. In the New World, populations of feral European cats, pigs, horses, and cattle are common, and the Burmese python and green iguana are considered problematic in Florida. In the Old World, the Eastern gray squirrel has been particularly successful in colonising Great Britain, and populations of raccoons can now be found in some regions of Germany, the Caucasus, and Japan. Fur farm escapees such as coypu and American mink have extensive populations.


title: Jet engine

text: A jet engine is a type of reaction engine discharging a fast-moving jet of heated gas (usually air) that generates thrust by jet propulsion. While this broad definition can include rocket, water jet, and hybrid propulsion, the term typically refers to an internal combustion airbreathing jet engine such as a turbojet, turbofan, ramjet, or pulse jet. In general, jet engines are internal combustion engines.


title: Jet engine

text: Airbreathing jet engines typically feature a rotating air compressor powered by a turbine, with the leftover power providing thrust through the propelling nozzle—this process is known as the Brayton thermodynamic cycle. Jet aircraft use such engines for long-distance travel. Early jet aircraft used turbojet engines that were relatively inefficient for subsonic flight. Most modern subsonic jet aircraft use more complex high-bypass turbofan engines. They give higher speed and greater fuel efficiency than piston and propeller aeroengines over long distances. A few air-breathing engines made for high speed applications (ramjets and scramjets) use the ram effect of the vehicle's speed instead of a mechanical compressor.


title: Jet engine

text: The thrust of a typical jetliner engine went from (de Havilland Ghost turbojet) in the 1950s to (General Electric GE90 turbofan) in the 1990s, and their reliability went from 40 in-flight shutdowns per 100,000 engine flight hours to less than 1 per 100,000 in the late 1990s. This, combined with greatly decreased fuel consumption, permitted routine transatlantic flight by twin-engined airliners by the turn of the century, where previously a similar journey would have required multiple fuel stops.


title: Jet engine

text: The principle of the jet engine is not new; however, the technical advances necessary to make the idea work did not come to fruition until the 20th century.


title: Jet engine

text: A rudimentary demonstration of jet power dates back to the aeolipile, a device described by Hero of Alexandria in 1st-century Egypt. This device directed steam power through two nozzles to cause a sphere to spin rapidly on its axis. It was seen as a curiosity. Meanwhile, practical applications of the turbine can be seen in the water wheel and the windmill.


title: Jet engine

text: Historians have further traced the theoretical origin of the principles of jet engines to traditional Chinese firework and rocket propulsion systems. Such devices' use for flight is documented in the story of Ottoman soldier Lagâri Hasan Çelebi, who reportedly achieved flight using a cone-shaped rocket in 1633.


title: Jet engine

text: The earliest attempts at airbreathing jet engines were hybrid designs in which an external power source first compressed air, which was then mixed with fuel and burned for jet thrust. The Caproni Campini N.1, and the Japanese Tsu-11 engine intended to power Ohka kamikaze planes towards the end of World War II were unsuccessful.


title: Jet engine

text: Even before the start of World War II, engineers were beginning to realize that engines driving propellers were approaching limits due to issues related to propeller efficiency, which declined as blade tips approached the speed of sound. If aircraft performance were to increase beyond such a barrier, a different propulsion mechanism was necessary. This was the motivation behind the development of the gas turbine engine, the most common form of jet engine.


title: Jet engine

text: The key to a practical jet engine was the gas turbine, extracting power from the engine itself to drive the compressor. The gas turbine was not a new idea: the patent for a stationary turbine was granted to John Barber in England in 1791. The first gas turbine to successfully run self-sustaining was built in 1903 by Norwegian engineer Ægidius Elling. Such engines did not reach manufacture due to issues of safety, reliability, weight and, especially, sustained operation.


title: Jet engine

text: The first patent for using a gas turbine to power an aircraft was filed in 1921 by Maxime Guillaume. His engine was an axial-flow turbojet, but was never constructed, as it would have required considerable advances over the state of the art in compressors. Alan Arnold Griffith published "An Aerodynamic Theory of Turbine Design" in 1926 leading to experimental work at the RAE.


title: Jet engine

text: In 1928, RAF College Cranwell cadet Frank Whittle formally submitted his ideas for a turbojet to his superiors. In October 1929, he developed his ideas further. On 16 January 1930, in England, Whittle submitted his first patent (granted in 1932). The patent showed a two-stage axial compressor feeding a single-sided centrifugal compressor. Practical axial compressors were made possible by ideas from A.A.Griffith in a seminal paper in 1926 ("An Aerodynamic Theory of Turbine Design"). Whittle would later concentrate on the simpler centrifugal compressor only. Whittle was unable to interest the government in his invention, and development continued at a slow pace.


title: Jet engine

text: In Spain, pilot and engineer Virgilio Leret Ruiz was granted a patent for a jet engine design in March 1935. Republican president Manuel Azaña arranged for initial construction at the Hispano-Suiza aircraft factory in Madrid in 1936, but Leret was executed months later by Francoist Moroccan troops after unsuccessfully defending his seaplane base on the first days of the Spanish Civil War. His plans, hidden from Francoists, were secretly given to the British embassy in Madrid a few years later by his wife, Carlota O'Neill, upon her release from prison.


title: Jet engine

text: In 1935, Hans von Ohain started work on a similar design to Whittle's in Germany, both compressor and turbine being radial, on opposite sides of the same disc, initially unaware of Whittle's work. Von Ohain's first device was strictly experimental and could run only under external power, but he was able to demonstrate the basic concept. Ohain was then introduced to Ernst Heinkel, one of the larger aircraft industrialists of the day, who immediately saw the promise of the design. Heinkel had recently purchased the Hirth engine company, and Ohain and his master machinist Max Hahn were set up there as a new division of the Hirth company. They had their first HeS 1 centrifugal engine running by September 1937. Unlike Whittle's design, Ohain used hydrogen as fuel, supplied under external pressure. Their subsequent designs culminated in the gasoline-fuelled HeS 3 of , which was fitted to Heinkel's simple and compact He 178 airframe and flown by Erich Warsitz in the early morning of August 27, 1939, from Rostock-Marienehe aerodrome, an impressively short time for development. The He 178 was the world's first jet plane. Heinkel applied for a US patent covering the Aircraft Power Plant by Hans Joachim Pabst von Ohain on May 31, 1939; patent number US2256198, with M Hahn referenced as inventor. Von Ohain´s design, an axial-flow engine, as opposed to Whittle's centrifugal flow engine, was eventually adopted by most manufacturers by the 1950's.


title: Jet engine

text: Austrian Anselm Franz of Junkers' engine division ("Junkers Motoren" or "Jumo") introduced the axial-flow compressor in their jet engine. Jumo was assigned the next engine number in the RLM 109-0xx numbering sequence for gas turbine aircraft powerplants, "004", and the result was the Jumo 004 engine. After many lesser technical difficulties were solved, mass production of this engine started in 1944 as a powerplant for the world's first jet-fighter aircraft, the Messerschmitt Me 262 (and later the world's first jet-bomber aircraft, the Arado Ar 234). A variety of reasons conspired to delay the engine's availability, causing the fighter to arrive too late to improve Germany's position in World War II, however this was the first jet engine to be used in service.


title: Jet engine

text: Meanwhile, in Britain the Gloster E28/39 had its maiden flight on 15 May 1941 and the Gloster Meteor finally entered service with the RAF in July 1944. These were powered by turbojet engines from Power Jets Ltd., set up by Frank Whittle. The first two operational turbojet aircraft, the Messerschmitt Me 262 and then the Gloster Meteor entered service within three months of each other in 1944, the Me 262 in April and the Gloster Meteor in July, so the Meteor only saw around 15 aircraft enter World War II action , while up to 1400 Me 262 were produced, with 300 entering combat, delivering the first ground attacks and air combat victories of jet planes.


title: Jet engine

text: Following the end of the war the German jet aircraft and jet engines were extensively studied by the victorious allies and contributed to work on early Soviet and US jet fighters. The legacy of the axial-flow engine is seen in the fact that practically all jet engines on fixed-wing aircraft have had some inspiration from this design.


title: Jet engine

text: By the 1950s, the jet engine was almost universal in combat aircraft, with the exception of cargo, liaison and other specialty types. By this point, some of the British designs were already cleared for civilian use, and had appeared on early models like the de Havilland Comet and Avro Canada Jetliner. By the 1960s, all large civilian aircraft were also jet powered, leaving the piston engine in low-cost niche roles such as cargo flights.


title: Jet engine

text: The efficiency of turbojet engines was still rather worse than piston engines, but by the 1970s, with the advent of high-bypass turbofan jet engines (an innovation not foreseen by the early commentators such as Edgar Buckingham, at high speeds and high altitudes that seemed absurd to them), fuel efficiency was about the same as the best piston and propeller engines.


title: Jet engine

text: Jet engines power jet aircraft, cruise missiles and unmanned aerial vehicles. In the form of rocket engines they power fireworks, model rocketry, spaceflight, and military missiles.


title: Jet engine

text: Jet engines have propelled high speed cars, particularly drag racers, with the all-time record held by a rocket car. A turbofan powered car, ThrustSSC, currently holds the land speed record.


title: Jet engine

text: Jet engine designs are frequently modified for non-aircraft applications, as industrial gas turbines or marine powerplants. These are used in electrical power generation, for powering water, natural gas, or oil pumps, and providing propulsion for ships and locomotives. Industrial gas turbines can create up to 50,000 shaft horsepower. Many of these engines are derived from older military turbojets such as the Pratt & Whitney J57 and J75 models. There is also a derivative of the P&W JT8D low-bypass turbofan that creates up to 35,000 horsepower (HP)


title: Jet engine

text: Jet engines are also sometimes developed into, or share certain components such as engine cores, with turboshaft and turboprop engines, which are forms of gas turbine engines that are typically used to power helicopters and some propeller-driven aircraft.


title: Jet engine

text: There are a large number of different types of jet engines, all of which achieve forward thrust from the principle of "jet propulsion".


title: Jet engine

text: Commonly aircraft are propelled by airbreathing jet engines. Most airbreathing jet engines that are in use are turbofan jet engines, which give good efficiency at speeds just below the speed of sound.


title: Jet engine

text: Gas turbines are rotary engines that extract energy from a flow of combustion gas. They have an upstream compressor coupled to a downstream turbine with a combustion chamber in-between. In aircraft engines, those three core components are often called the "gas generator". There are many different variations of gas turbines, but they all use a gas generator system of some type.


title: Jet engine

text: A turbojet engine is a gas turbine engine that works by compressing air with an inlet and a compressor (axial, centrifugal, or both), mixing fuel with the compressed air, burning the mixture in the combustor, and then passing the hot, high pressure air through a turbine and a nozzle. The compressor is powered by the turbine, which extracts energy from the expanding gas passing through it. The engine converts internal energy in the fuel to kinetic energy in the exhaust, producing thrust. All the air ingested by the inlet is passed through the compressor, combustor, and turbine, unlike the turbofan engine described below.


title: Jet engine

text: Turbofans differ from turbojets in that they have an additional fan at the front of the engine, which accelerates air in a duct bypassing the core gas turbine engine. Turbofans are the dominant engine type for medium and long-range airliners.


title: Jet engine

text: Turbofans are usually more efficient than turbojets at subsonic speeds, but at high speeds their large frontal area generates more drag. Therefore, in supersonic flight, and in military and other aircraft where other considerations have a higher priority than fuel efficiency, fans tend to be smaller or absent.


title: Jet engine

text: Because of these distinctions, turbofan engine designs are often categorized as low-bypass or high-bypass, depending upon the amount of air which bypasses the core of the engine. Low-bypass turbofans have a bypass ratio of around 2:1 or less.


title: Jet engine

text: Ram compression jet engines are airbreathing engines similar to gas turbine engines and they both follow the Brayton cycle. Gas turbine and ram powered engines differ, however, in how they compress the incoming airflow. Whereas gas turbine engines use axial or centrifugal compressors to compress incoming air, ram engines rely only on air compressed through the inlet or diffuser. A ram engine thus requires a substantial initial forward airspeed before it can function. Ram powered engines are considered the most simple type of air breathing jet engine because they can contain no moving parts.


title: Jet engine

text: Ramjets are ram powered jet engines. They are mechanically simple, and operate less efficiently than turbojets except at very high speeds.


title: Jet engine

text: Scramjets differ mainly in the fact that the air does not slow to subsonic speeds. Rather, they use supersonic combustion. They are efficient at even higher speed. Very few have been built or flown.


title: Jet engine

text: The rocket engine uses the same basic physical principles of thrust as a form of reaction engine, but is distinct from the jet engine in that it does not require atmospheric air to provide oxygen; the rocket carries all components of the reaction mass. However some definitions treat it as a form of jet propulsion.


title: Jet engine

text: This type of engine is used for launching satellites, space exploration and manned access, and permitted landing on the moon in 1969.


title: Jet engine

text: Rocket engines are used for high altitude flights, or anywhere where very high accelerations are needed since rocket engines themselves have a very high thrust-to-weight ratio.


title: Jet engine

text: However, the high exhaust speed and the heavier, oxidizer-rich propellant results in far more propellant use than turbofans. Even so, at extremely high speeds they become energy-efficient.


title: Jet engine

text: Where formula_2 is the net thrust, formula_3 is the specific impulse, formula_4 is a standard gravity, formula_5 is the propellant flow in kg/s, formula_6 is the cross-sectional area at the exit of the exhaust nozzle, and formula_7 is the atmospheric pressure.


title: Jet engine

text: A water jet, or pump-jet, is a marine propulsion system that uses a jet of water. The mechanical arrangement may be a ducted propeller with nozzle, or a centrifugal compressor and nozzle. The pump-jet must be driven by a separate engine such as a Diesel or gas turbine.


title: Jet engine

text: All jet engines are reaction engines that generate thrust by emitting a jet of fluid rearwards at relatively high speed. The forces on the inside of the engine needed to create this jet give a strong thrust on the engine which pushes the craft forwards.


title: Jet engine

text: Jet engines make their jet from propellant stored in tanks that are attached to the engine (as in a 'rocket') as well as in duct engines (those commonly used on aircraft) by ingesting an external fluid (very typically air) and expelling it at higher speed.


title: Jet engine

text: The propelling nozzle is the key component of all jet engines as it creates the exhaust jet. Propelling nozzles turn internal and pressure energy into high velocity kinetic energy. The total pressure and temperature don't change through the nozzle but their static values drop as the gas speeds up.


title: Jet engine

text: The velocity of the air entering the nozzle is low, about Mach 0.4, a prerequisite for minimizing pressure losses in the duct leading to the nozzle. The temperature entering the nozzle may be as low as sea level ambient for a fan nozzle in the cold air at cruise altitudes. It may be as high as the 1000K exhaust gas temperature for a supersonic afterburning engine or 2200K with afterburner lit. The pressure entering the nozzle may vary from 1.5 times the pressure outside the nozzle, for a single stage fan, to 30 times for the fastest manned aircraft at mach 3+.


title: Jet engine

text: Convergent nozzles are only able to accelerate the gas up to local sonic (Mach 1) conditions. To reach high flight speeds, even greater exhaust velocities are required, and so a convergent-divergent nozzle is often used on high-speed aircraft.


title: Jet engine

text: The nozzle thrust is highest if the static pressure of the gas reaches the ambient value as it leaves the nozzle. This only happens if the nozzle exit area is the correct value for the nozzle pressure ratio (npr). Since the npr changes with engine thrust setting and flight speed this is seldom the case. Also at supersonic speeds the divergent area is less than required to give complete internal expansion to ambient pressure as a trade-off with external body drag. Whitford gives the F-16 as an example. Other underexpanded examples were the XB-70 and SR-71.


title: Jet engine

text: The nozzle size, together with the area of the turbine nozzles, determines the operating pressure of the compressor.


title: Jet engine

text: This overview highlights where energy losses occur in complete jet aircraft powerplants or engine installations.


title: Jet engine

text: A jet engine at rest, as on a test stand, sucks in fuel and generates thrust. How well it does this is judged by how much fuel it uses and what force is required to restrain it. This is a measure of its efficiency. If something deteriorates inside the engine (known as performance deterioration) it will be less efficient and this will show when the fuel produces less thrust. If a change is made to an internal part which allows the air/combustion gases to flow more smoothly the engine will be more efficient and use less fuel. A standard definition is used to assess how different things change engine efficiency and also to allow comparisons to be made between different engines. This definition is called specific fuel consumption, or how much fuel is needed to produce one unit of thrust. For example, it will be known for a particular engine design that if some bumps in a bypass duct are smoothed out the air will flow more smoothly giving a pressure loss reduction of x% and y% less fuel will be needed to get the take-off thrust, for example. This understanding comes under the engineering discipline Jet engine performance. How efficiency is affected by forward speed and by supplying energy to aircraft systems is mentioned later.


title: Jet engine

text: The efficiency of the engine is controlled primarily by the operating conditions inside the engine which are the pressure produced by the compressor and the temperature of the combustion gases at the first set of rotating turbine blades. The pressure is the highest air pressure in the engine. The turbine rotor temperature is not the highest in the engine but is the highest at which energy transfer takes place ( higher temperatures occur in the combustor). The above pressure and temperature are shown on a Thermodynamic cycle diagram.


title: Jet engine

text: The efficiency is further modified by how smoothly the air and the combustion gases flow through the engine, how well the flow is aligned (known as incidence angle) with the moving and stationary passages in the compressors and turbines. Non-optimum angles, as well as non-optimum passage and blade shapes can cause thickening and separation of Boundary layers and formation of Shock waves. It is important to slow the flow (lower speed means less pressure losses or Pressure drop) when it travels through ducts connecting the different parts. How well the individual components contribute to turning fuel into thrust is quantified by measures like efficiencies for the compressors, turbines and combustor and pressure losses for the ducts. These are shown as lines on a Thermodynamic cycle diagram.


title: Jet engine

text: The engine efficiency, or thermal efficiency, known as formula_8. is dependent on the Thermodynamic cycle parameters, maximum pressure and temperature, and on component efficiencies, formula_9, formula_10 and formula_11 and duct pressure losses.


title: Jet engine

text: The engine needs compressed air for itself just to run successfully. This air comes from its own compressor and is called secondary air. It does not contribute to making thrust so makes the engine less efficient. It is used to preserve the mechanical integrity of the engine, to stop parts overheating and to prevent oil escaping from bearings for example. Only some of this air taken from the compressors returns to the turbine flow to contribute to thrust production. Any reduction in the amount needed improves the engine efficiency. Again, it will be known for a particular engine design that a reduced requirement for cooling flow of x% will reduce the specific fuel consumption by y%. In other words, less fuel will be required to give take-off thrust, for example. The engine is more efficient.


title: Jet engine

text: All of the above considerations are basic to the engine running on its own and, at the same time, doing nothing useful, i.e. it is not moving an aircraft or supplying energy for the aircraft's electrical, hydraulic and air systems. In the aircraft the engine gives away some of its thrust-producing potential, or fuel, to power these systems. These requirements, which cause installation losses, reduce its efficiency. It is using some fuel that does not contribute to the engine's thrust.


title: Jet engine

text: Finally, when the aircraft is flying the propelling jet itself contains wasted kinetic energy after it has left the engine. This is quantified by the term propulsive, or Froude, efficiency formula_12 and may be reduced by redesigning the engine to give it bypass flow and a lower speed for the propelling jet, for example as a turboprop or turbofan engine. At the same time forward speed increases the formula_8 by increasing the Overall pressure ratio.


title: Jet engine

text: The formula_15 at flight speed depends on how well the intake compresses the air before it is handed over to the engine compressors. The intake compression ratio, which can be as high as 32:1 at Mach 3, adds to that of the engine compressor to give the Overall pressure ratio and formula_8 for the Thermodynamic cycle. How well it does this is defined by its pressure recovery or measure of the losses in the intake. Mach 3 manned flight has provided an interesting illustration of how these losses can increase dramatically in an instant. The North American XB-70 Valkyrie and Lockheed SR-71 Blackbird at Mach 3 each had pressure recoveries of about 0.8, due to relatively low losses during the compression process, i.e. through systems of multiple shocks. During an 'unstart' the efficient shock system would be replaced by a very inefficient single shock beyond the inlet and an intake pressure recovery of about 0.3 and a correspondingly low pressure ratio.


title: Jet engine

text: The propelling nozzle at speeds above about Mach 2 usually has extra internal thrust losses because the exit area is not big enough as a trade-off with external afterbody drag.


title: Jet engine

text: Although a bypass engine improves propulsive efficiency it incurs losses of its own inside the engine itself. Machinery has to be added to transfer energy from the gas generator to a bypass airflow. The low loss from the propelling nozzle of a turbojet is added to with extra losses due to inefficiencies in the added turbine and fan. These may be included in a transmission, or transfer, efficiency formula_17. However, these losses are more than made up by the improvement in propulsive efficiency. There are also extra pressure losses in the bypass duct and an extra propelling nozzle.


title: Jet engine

text: With the advent of turbofans with their loss-making machinery what goes on inside the engine has been separated by Bennett, for example, between gas generator and transfer machinery giving formula_18.


title: Jet engine

text: for all jet engines the "propulsive efficiency" is highest as the exhaust jet velocity gets closer to the vehicle speed as this gives the smallest residual kinetic energy. For an airbreathing engine an exhaust velocity equal to the vehicle velocity, or a formula_12 equal to one, gives zero thrust with no net momentum change. The formula for air-breathing engines moving at speed formula_25 with an exhaust velocity formula_26, and neglecting fuel flow, is:


title: Jet engine

text: In addition to propulsive efficiency, another factor is "cycle efficiency"; a jet engine is a form of heat engine. Heat engine efficiency is determined by the ratio of temperatures reached in the engine to that exhausted at the nozzle. This has improved constantly over time as new materials have been introduced to allow higher maximum cycle temperatures. For example, composite materials, combining metals with ceramics, have been developed for HP turbine blades, which run at the maximum cycle temperature. The efficiency is also limited by the overall pressure ratio that can be achieved. Cycle efficiency is highest in rocket engines (~60+%), as they can achieve extremely high combustion temperatures. Cycle efficiency in turbojet and similar is nearer to 30%, due to much lower peak cycle temperatures.


title: Jet engine

text: is almost 100%. It decreases nonlinearly to 98% at altitude cruise conditions. Air-fuel ratio ranges from 50:1 to 130:1. For any type of combustion chamber there is a "rich" and "weak limit" to the air-fuel ratio, beyond which the flame is extinguished. The range of air-fuel ratio between the rich and weak limits is reduced with an increase of air velocity. If the


title: Jet engine

text: A closely related (but different) concept to energy efficiency is the rate of consumption of propellant mass. Propellant consumption in jet engines is measured by specific fuel consumption, specific impulse, or effective exhaust velocity. They all measure the same thing. Specific impulse and effective exhaust velocity are strictly proportional, whereas specific fuel consumption is inversely proportional to the others.


title: Jet engine

text: For air-breathing engines such as turbojets, energy efficiency and propellant (fuel) efficiency are much the same thing, since the propellant is a fuel and the source of energy. In rocketry, the propellant is also the exhaust, and this means that a high energy propellant gives better propellant efficiency but can in some cases actually give "lower" energy efficiency.


title: Jet engine

text: It can be seen in the table (just below) that the subsonic turbofans such as General Electric's CF6 turbofan use a lot less fuel to generate thrust for a second than did the Concorde's Rolls-Royce/Snecma Olympus 593 turbojet. However, since energy is force times distance and the distance per second was greater for the Concorde, the actual power generated by the engine for the same amount of fuel was higher for the Concorde at Mach 2 than the CF6. Thus, the Concorde's engines were more efficient in terms of energy per mile.


title: Jet engine

text: The thrust-to-weight ratio of jet engines with similar configurations varies with scale, but is mostly a function of engine construction technology. For a given engine, the lighter the engine, the better the thrust-to-weight is, the less fuel is used to compensate for drag due to the lift needed to carry the engine weight, or to accelerate the mass of the engine.


title: Jet engine

text: As can be seen in the following table, rocket engines generally achieve much higher thrust-to-weight ratios than duct engines such as turbojet and turbofan engines. This is primarily because rockets almost universally use dense liquid or solid reaction mass which gives a much smaller volume and hence the pressurization system that supplies the nozzle is much smaller and lighter for the same performance. Duct engines have to deal with air which is two to three orders of magnitude less dense and this gives pressures over much larger areas, which in turn results in more engineering materials being needed to hold the engine together and for the air compressor.


title: Jet engine

text: Propeller engines handle larger air mass flows, and give them smaller acceleration, than jet engines. Since the increase in air speed is small, at high flight speeds the thrust available to propeller-driven aeroplanes is small. However, at low speeds, these engines benefit from relatively high propulsive efficiency.


title: Jet engine

text: On the other hand, turbojets accelerate a much smaller mass flow of intake air and burned fuel, but they then reject it at very high speed. When a de Laval nozzle is used to accelerate a hot engine exhaust, the outlet velocity may be locally supersonic. Turbojets are particularly suitable for aircraft travelling at very high speeds.


title: Jet engine

text: Turbofans have a mixed exhaust consisting of the bypass air and the hot combustion product gas from the core engine. The amount of air that bypasses the core engine compared to the amount flowing into the engine determines what is called a turbofan's bypass ratio (BPR).


title: Jet engine

text: While a turbojet engine uses all of the engine's output to produce thrust in the form of a hot high-velocity exhaust gas jet, a turbofan's cool low-velocity bypass air yields between 30% and 70% of the total thrust produced by a turbofan system.


title: Jet engine

text: Rocket engines have extremely high exhaust velocity and thus are best suited for high speeds (hypersonic) and great altitudes. At any given throttle, the thrust and efficiency of a rocket motor improves slightly with increasing altitude (because the back-pressure falls thus increasing net thrust at the nozzle exit plane), whereas with a turbojet (or turbofan) the falling density of the air entering the intake (and the hot gases leaving the nozzle) causes the net thrust to decrease with increasing altitude. Rocket engines are more efficient than even scramjets above roughly Mach 15.


title: Jet engine

text: With the exception of scramjets, jet engines, deprived of their inlet systems can only accept air at around half the speed of sound. The inlet system's job for transonic and supersonic aircraft is to slow the air and perform some of the compression.


title: Jet engine

text: The limit on maximum altitude for engines is set by flammability – at very high altitudes the air becomes too thin to burn, or after compression, too hot. For turbojet engines altitudes of about 40 km appear to be possible, whereas for ramjet engines 55 km may be achievable. Scramjets may theoretically manage 75 km. Rocket engines of course have no upper limit.


title: Jet engine

text: At more modest altitudes, flying faster compresses the air at the front of the engine, and this greatly heats the air. The upper limit is usually thought to be about Mach 5–8, as above about Mach 5.5, the atmospheric nitrogen tends to react due to the high temperatures at the inlet and this consumes significant energy. The exception to this is scramjets which may be able to achieve about Mach 15 or more, as they avoid slowing the air, and rockets again have no particular speed limit.


title: Jet engine

text: The noise emitted by a jet engine has many sources. These include, in the case of gas turbine engines, the fan, compressor, combustor, turbine and propelling jet/s.


title: Jet engine

text: The propelling jet produces jet noise which is caused by the violent mixing action of the high speed jet with the surrounding air. In the subsonic case the noise is produced by eddies and in the supersonic case by Mach waves. The sound power radiated from a jet varies with the jet velocity raised to the eighth power for velocities up to 2,000 ft/sec and varies with the velocity cubed above 2,000 ft/sec. Thus, the lower speed exhaust jets emitted from engines such as high bypass turbofans are the quietest, whereas the fastest jets, such as rockets, turbojets, and ramjets, are the loudest. For commercial jet aircraft the jet noise has reduced from the turbojet through bypass engines to turbofans as a result of a progressive reduction in propelling jet velocities. For example, the JT8D, a bypass engine, has a jet velocity of 1450 ft/sec whereas the JT9D, a turbofan, has jet velocities of 885 ft/sec (cold) and 1190 ft/sec (hot).


title: Jet engine

text: The advent of the turbofan replaced the very distinctive jet noise with another sound known as "buzz saw" noise. The origin is the shockwaves originating at the supersonic fan blades at takeoff thrust.


title: Jet engine

text: Adequate heat transfer away from the working parts of the jet engine is critical to maintaining strength of engine materials and ensuring long life for the engine.


title: Jet engine

text: After 2016, research is ongoing in the development of transpiration cooling techniques to jet engine components.


title: Jet engine

text: In a jet engine, each major rotating section usually has a separate gauge devoted to monitoring its speed of rotation.


title: Jet engine

text: Depending on the make and model, a jet engine may have an N gauge that monitors the low-pressure compressor section and/or fan speed in turbofan engines. The gas generator section may be monitored by an N gauge, while triple spool engines may have an N gauge as well. Each engine section rotates at many thousands RPM. Their gauges therefore are calibrated in percent of a nominal speed rather than actual RPM, for ease of display and interpretation.


title: Kashyapa

text: Kashyapa (, ) is a revered Vedic sage of Hinduism. He is one of the Saptarishis, the seven ancient sages of the "Rigveda". Kashyapa is the most ancient and venerated rishi, along with the other Saptarishis, listed in the colophon verse in the "Brihadaranyaka Upanishad".


title: Kashyapa

text: Kashyapa is an ancient name, referring to many different personalities in the ancient Hindu and Buddhist texts. The place Kashmir is named after him, as well as numerous other Sanskrit texts and Indian scriptures.


title: Kashyapa

text: Kashyapa means "turtle" in Sanskrit. According to Michael Witzel, it is related to Avestan "kasiiapa", Sogdian "kyšph", New Persian "kašaf", "kaš(a)p" which mean "tortoise", after which Kashaf Rūd or a river in Turkmenistan and Khorasan is named. Other relations include to Tokarian B "kaccāp" ("brainpan"), Tokarian A "kāccap" ("turtle", "tortoise"). Frits Staal agrees that Kaśyapa means tortoise but believes that it is a non-Indo-European word.


title: Kashyapa

text: Kashyapa is credited with composing a few hymns in the Rigveda, mainly in Mandala IX. He and his family of students are mainly composers of hymns for Soma Pavamāna ("self-purifying Soma"), which represents a single moment in the Soma sacrifice.


title: Kashyapa

text: He is mentioned in verse 2.2.4 of the "Brihadaranyaka Upanishad", along with Atri, Vashistha, Vishvamitra, Jamadagni, Bharadwaja and Gotama. Kashyapa is also mentioned as the earliest rishi in colophon verse 6.5.3 of "Brihadaranyaka Upanishad", one of the oldest Upanishadic scriptures of Hinduism.


title: Kashyapa

text: Kashyapa is mentioned in other Vedas and numerous other Vedic texts. For example, in one of several cosmology-related hymns of Atharvaveda (~1000 BCE), Kashyapa is mentioned in the allegory-filled Book XIX:


title: Kashyapa

text: His name appears in Patanjali's ancient bhasya on verse 1.2.64 of Pāṇini. His name is very common in the Epic and Purana literature.


title: Kashyapa

text: In Buddhist Pali canonical texts such as "Digha Nikaya", Tevijja Sutta describes a discussion between the Buddha and Vedic scholars of his time. The Buddha names ten rishis, calls them "early sages" and makers of ancient verses that have been collected and chanted in his era, and among those ten rishi is Kassapa (the Pali spelling of Kashyapa in Sanskrit).


title: Kashyapa

text: Despite its etymological origins being uncertain, Kashmir got its name from Kashyapa Rishi. According to Christopher Snedden, the name Kashmir could have been a shortened form of "Kashyapa Mira", or the "lake of the sage Kashyapa". Alternatively, it may come from a Kashmiri or Sanskrit term that means "to dry up water". It could also have been derived from the term "Kashyapa Meru", which means the sacred mountains of Kashyapa.


title: Kashyapa

text: In ancient texts of Greece, linked to the expedition of Alexander, this land has been called "Kasperia", possibly a contraction of "Kasyapamira". The word "Kaspapyros" appears in Greek geographer Hekataois text, and as "Kaspatyros" in Herodotus who states that Skylax the Karyandian began in Kaspatyros to trace the path of Indus river from the mountains to where it drained in the sea. Kaspatyros may be same as Kaspa-pyrus or Kashyapa-pura (city of Kashyapa) in other texts.


title: Kashyapa

text: Kashyapa is mentioned in numerous Hindu texts such as the "Puranas" and the Hindu Epics. The stories related to Kashyapa in different texts are widely inconsistent, and many are considered allegorical. For example, in the "Ramayana", he is married to the eight daughters of Daksha, while in the "Mahabharata" and "Vishnu Purana" he is described as married to thirteen daughters. Some of the names of the thirteen daughters Kashyapa married in the Hindu text "Vishnu Purana" are different than the list found in "Mahabharata". Some texts describe Kashyapa as the son of Marichi, ancestor of solar dynasty, a contemporary with Uttamapada the second king of Brahmavarta and who married daughters of Daksha Prajapati the son of Brahma, others mention about him marrying daughters of Daksha Prajapati the last king of Brahmavarta, 15 in male descent from Uttamapada. It may be supposed that there have existed several persons named Kashyapa all of whom are usually confounded.


title: Kashyapa

text: In some "Puranas", Kashyapa is said to have drained the Kashmir valley to make it inhabitable. Some interpret this legend to parallel the legend of Buddhist Manjushri draining Nepal and Tibet, wherein the "draining" is an allegory for teaching ideas and doctrines, removing stagnant waters of ignorance and extending learning and civilization into the valley. The Sindh city Multan (now in Pakistan), also called Mulasthana, has been interpreted alternatively as "Kashyapapura" in some stories after Kashyap. Yet another interpretation has been to associate Kashyapa as River Indus in the Sindh region. However, these interpretations and the links of Multan as Kashyapapura to Kashmir have been questioned.


title: Kashyapa

text: According to the ancient legends, Kashyapa reclaimed that land from a vast lake, his school was based there, and the land was named after him.


title: Kashyapa

text: The "Puranas" and the Epics of Indian tradition mention Kashyapa and his genealogy numerous times. In the "Vishnu Purana", Kashyap marries thirteen daughters of Daksha: Aditi, Diti, Kadru, Danu, Arishta, Surasa, Surabhi, Vinata, Tamra, Krodhavasha, Ira, Vishva and Muni, while in the "Mahabharata", the names of these 13 wives are Aditi, Diti, Kala, Danayus, Danu, Simhika, Krodha, Pritha, Visva, Vinata, Kapila, Muni and Kadru. There are various interpretations. Scholar Vettam Mani, after analysing the epics and Puranas, concluded that Kashyapa may have married 21 women (13 of which were Daksha's daughters) — Aditi, Diti, Danu, Arishta, Surasha, Khasha, Surabhi, Vinata, Tamra, Krodhavasha, Ira, Kadru, Muni, Puloma, Kalaka, Nata, Danayus, Simhika, Pradha, Visva and Kapila.


title: Kashyapa

text: Kashyapa, in the "Vishnu Purana" and "Vayu Purana", is attributed to be the father of the Devas, Danavas, Yakshas, Daityas and all living creatures with various daughters of Daksha. He married Aditi, with whom he fathered the Adityas, and in two inconsistent versions Vamana, an "avatar" of Vishnu, is the child of Aditi and Kashyapa. In these religious texts, Kashyapa is the brother-in-law of Dharma and Adharma, both of whom are also described as married to other daughters of Daksha.


title: Kashyapa

text: Sage Kaśyapa also incarnated as Vasudeva, the father of Lord Krishna due to a curse that Lord Brahmā unleashed upon him. Once, the sage performed a Yajña (a Vedic ritual) in his hermitage in order to offer oblations to the Devas for the welfare of the beings in the world. To perform the ritual, Sage Kaśyapa required offerings such as milk, ghee etc., for which he sought the help of Lord Varuṇa. When Lord Varuṇa manifested before him, Sage Kaśyapa requested him for a boon of limitless offerings to perform the Yajña successfully. Lord Varuṇa offered him a holy cow which would provide him with limitless offerings. He then told the sage that the holy cow would be taken back once the Yajña was over. The Yajña went on for several days, and with the presence of the holy cow, the sage never faced any obstacles.


title: Kashyapa

text: Realizing the miraculous power of the cow, he was overcome with greed and desired to own the cow forever. He did not return the cow to Lord Varuṇa even after the Yajña was over. Lord Varuṇa appeared in front of Sage Kaśyapa and told him that the cow was given to him as a boon, only for the Yajña, and now that the Yajña was over, it had to be returned as it belonged to the heaven. Sage Kaśyapa refused to part with the cow and told Lord Varuṇa that whatever is offered to a Brāhmaṇa should never be sought back, and whoever does that would turn out to be a sinner.


title: Kashyapa

text: Hence, Lord Varuṇa sought the help of Lord Brahmā who appeared before the sage and told him to get rid of his greed which is capable of destroying all his virtues. Nevertheless, Sage Kaśyapa remained firm in his resolve, which enraged Lord Brahmā who cursed him, saying that he would be born on earth again as a cowherd. Sage Kaśyapa repented for his mistake and pleaded Lord Brahmā to forgive him. Lord Brahmā also realized that he had cursed him in a haste, and told him that he would still be born as a cowherd in the Yadava clan, and Lord Vishnu would be born as his son. This was how Sage Kaśyapa was born as Vasudeva and became the father of Lord Krishna.


title: Kashyapa

text: Kashyapa is revered in the Hindu tradition, and numerous legends and texts composed in the medieval era are reverentially attributed to him in various Hindu traditions. Some treatises named after him or attributed to him include:


title: One Piece (season 19)

text: The nineteenth season of the "One Piece" anime series was produced by Toei Animation, and directed by Toshinori Fukuzawa. The season began broadcasting in Japan on Fuji Television on April 9, 2017. Like the rest of the series, it follows the adventures of Monkey D. Luffy and his Straw Hat Pirates. It contains two story arcs.


title: One Piece (season 19)

text: The first story arc, called "Whole Cake Island", adapts material from the rest of the 82nd volume to the beginning of the 90th volume of the manga by Eiichiro Oda. It deals with Luffy and his small team rescuing Sanji from his arranged marriage to finalize a political alliance between his own family, the Vinsmokes, and Big Mom's family.


title: One Piece (season 19)

text: The second story arc, called "Reverie", adapts material from the rest of the 90th volume. It deals with the royals from across the globe gathering for the Reverie, a seven day conference to discuss matters that could affect the world.


title: One Piece (season 19)

text: Three pieces of theme music are used for this season. The opening themes are by Kishidan and Hiroshi Kitadani for episodes 783 to 806, "Hope" by Namie Amuro for episodes 807 to 855, and "Super Powers" by V6 for episodes 856 to 891.


title: One Piece (season 19)

text: Writing for Anime News Network, Sam Leach awarded the first two "Reverie" episodes a "B−" and "B" rating; Leach praised the character interactions, but described the lengthy flashback sequences as "disposable" and argued that at times the anime's pacing was not sympathetic to the manga material it adapted.


title: Soha Ali Khan

text: Soha Ali Khan Pataudi Khemu (born 4 October 1978) is an Indian actress who has worked in Hindi, Bengali and English films. She is the daughter of veteran actress Sharmila Tagore and former Indian cricket captain Mansoor Ali Khan Pataudi, and the younger sister of actor Saif Ali Khan. She started her acting career with the romantic comedy film "Dil Maange More" (2004), and is best known for her role in the drama film "Rang De Basanti" (2006), for which she was nominated for the Filmfare Award for Best Supporting Actress.


title: Soha Ali Khan

text: Pataudi was born on 4 October 1978 in New Delhi, India, to the Pataudi family as the Nawab of Pataudis. Hailing from the Pashtun ancestry, she is the youngest daughter of Mansoor Ali Khan Pataudi, the 9th Nawab of Pataudi, and Sharmila Tagore, an Indian actress. Both her father Mansoor Ali Khan Pataudi and paternal grandfather Iftikhar Ali Khan Pataudi were former captains of the Indian cricket team, while her grandmother, Sajida Sultan Pataudi, was the Begum of Bhopal. Her elder brother Saif Ali Khan is a Bollywood actor and her elder sister, Saba Ali Khan, is a jewellery designer and the mutawalli of Auqaf-e-Shahi. The titular Begum of Bhopal, Saleha Sultan, was her aunt, and through her, she is the first cousin of cricketer, Saad Bin Jung. The late major general of Pakistan, Sher Ali Khan Pataudi, is her great-granduncle, and the diplomat Shahryar Khan is her uncle, through her grandaunt Abida Sultan. She is the aunt of Sara Ali Khan and the sister-in-law of Kareena Kapoor Khan.


title: Soha Ali Khan

text: Soha attended The British School, in New Delhi, studied modern history at Balliol College, Oxford and earned a master's degree in International Relations from the London School of Economics and Political Science.


title: Soha Ali Khan

text: Soha made her acting debut with the Bollywood film "Dil Maange More!!!" (2004). She performed in the Bengali film "Antar Mahal" (2005), and was also a part of "Rang De Basanti" (2006). She appeared in "Khoya Khoya Chand" and in the 2009 film, "99". Her next release was "Tum Mile," opposite Emraan Hashmi. Soha hosted the game show "Godrej Khelo Jeeto Jiyo". She also appeared in the film "Mr Joe B. Carvalho". Khan's debut book, "The Perils of Being Moderately Famous", which features a collection of humorous anecdotes about her life as a royal princess, was published in 2017. In 2017, she acted in a short film, "Soundproof", which was directed by Aditya Kelgaonkar. It was screened at various film festivals and won awards at the New York Indian Film Festival, Indian Film Festival of Houston, Ottawa Indian Film Festival Awards, where it won best short film award; International Documentary and Short Film Festival of Kerala, where it won award for best short fiction; and Belgaum International Short Film Festival.


title: Soha Ali Khan

text: Pataudi got engaged to actor Kunal Khemu in July 2014 in Paris and married him in Mumbai on 25 January 2015. She gave birth to their daughter, Inaaya Naumi Khemu on 29 September 2017.


title: Prostaglandin

text: The prostaglandins (PG) are a group of physiologically active lipid compounds called eicosanoids having diverse hormone-like effects in animals. Prostaglandins have been found in almost every tissue in humans and other animals. They are derived enzymatically from the fatty acid arachidonic acid. Every prostaglandin contains 20 carbon atoms, including a 5-carbon ring. They are a subclass of eicosanoids and of the prostanoid class of fatty acid derivatives.


title: Prostaglandin

text: The structural differences between prostaglandins account for their different biological activities. A given prostaglandin may have different and even opposite effects in different tissues in some cases. The ability of the same prostaglandin to stimulate a reaction in one tissue and inhibit the same reaction in another tissue is determined by the type of receptor to which the prostaglandin binds. They act as autocrine or paracrine factors with their target cells present in the immediate vicinity of the site of their secretion. Prostaglandins differ from endocrine hormones in that they are not produced at a specific site but in many places throughout the human body.


title: Prostaglandin

text: Prostaglandins are powerful, locally-acting vasodilators and inhibit the aggregation of blood platelets. Through their role in vasodilation, prostaglandins are also involved in inflammation. They are synthesized in the walls of blood vessels and serve the physiological function of preventing needless clot formation, as well as regulating the contraction of smooth muscle tissue. Conversely, thromboxanes (produced by platelet cells) are vasoconstrictors and facilitate platelet aggregation. Their name comes from their role in clot formation (thrombosis).


title: Prostaglandin

text: Specific prostaglandins are named with a letter (which indicates the type of ring structure) followed by a number (which indicates the number of double bonds in the hydrocarbon structure). For example, prostaglandin E1 is abbreviated PGE, and prostaglandin I2 is abbreviated PGI.


title: Prostaglandin

text: Systematic studies of prostaglandins began in 1930, when Kurzrock and Lieb found that human seminal fluid caused either stimulation or relaxation of strips of isolated human uterus. They noted the curious finding that uteri from patients who had gone through successful pregnancies responded to the fluid with relaxation, while uteri from sterile women responded with contraction upon addition of this seminal fluid. The name "prostaglandin" derives from the prostate gland, chosen when prostaglandin was first isolated from seminal fluid in 1935 by the Swedish physiologist Ulf von Euler, and independently by the Irish-English physiologist Maurice Walter Goldblatt (1895–1967). Prostaglandins were believed to be part of the prostatic secretions, and eventually were discovered to be produced by the seminal vesicles. Later, it was shown that many other tissues secrete prostaglandins and that they perform a variety of functions. The first total syntheses of prostaglandin F and prostaglandin E were reported by E. J. Corey in 1969, an achievement for which he was awarded the Japan Prize in 1989.


title: Prostaglandin

text: In 1971, it was determined that aspirin-like drugs could inhibit the synthesis of prostaglandins. The biochemists Sune K. Bergström, Bengt I. Samuelsson and John R. Vane jointly received the 1982 Nobel Prize in Physiology or Medicine for their research on prostaglandins.


title: Prostaglandin

text: Prostaglandins are found in most tissues and organs. They are produced by almost all nucleated cells. They are autocrine and paracrine lipid mediators that act upon platelets, endothelium, uterine and mast cells. They are synthesized in the cell from the fatty acid arachidonic acid.


title: Prostaglandin

text: Arachidonic acid is created from diacylglycerol via phospholipase-A, then brought to either the cyclooxygenase pathway or the lipoxygenase pathway. The cyclooxygenase pathway produces thromboxane, prostacyclin and prostaglandin D, E and F. Alternatively, the lipoxygenase enzyme pathway is active in leukocytes and in macrophages and synthesizes leukotrienes.


title: Prostaglandin

text: Prostaglandins were originally believed to leave the cells via passive diffusion because of their high lipophilicity. The discovery of the prostaglandin transporter (PGT, SLCO2A1), which mediates the cellular uptake of prostaglandin, demonstrated that diffusion alone cannot explain the penetration of prostaglandin through the cellular membrane. The release of prostaglandin has now also been shown to be mediated by a specific transporter, namely the multidrug resistance protein 4 (MRP4, ABCC4), a member of the ATP-binding cassette transporter superfamily. Whether MRP4 is the only transporter releasing prostaglandins from the cells is still unclear.


title: Prostaglandin

text: Prostaglandins are produced following the sequential oxygenation of arachidonic acid, DGLA or EPA by cyclooxygenases (COX-1 and COX-2) and terminal prostaglandin synthases. The classic dogma is as follows:


title: Prostaglandin

text: However, while COX-1 and COX-2 are both located in the blood vessels, stomach and the kidneys, prostaglandin levels are increased by COX-2 in scenarios of inflammation and growth.


title: Prostaglandin

text: Prostaglandin E (PGE) — the most abundant prostaglandin — is generated from the action of prostaglandin E synthases on prostaglandin H (prostaglandin H2, PGH). Several prostaglandin E synthases have been identified. To date, microsomal prostaglandin E synthase-1 emerges as a key enzyme in the formation of PGE.


title: Prostaglandin

text: Terminal prostaglandin synthases have been identified that are responsible for the formation of other prostaglandins. For example, hematopoietic and lipocalin prostaglandin D synthases (hPGDS and lPGDS) are responsible for the formation of PGD from PGH. Similarly, prostacyclin (PGI) synthase (PGIS) converts PGH into PGI. A thromboxane synthase (TxAS) has also been identified.


title: Prostaglandin

text: Prostaglandin-F synthase (PGFS) catalyzes the formation of 9α,11β-PGF from PGD and PGF from PGH in the presence of NADPH. This enzyme has recently been crystallized in complex with PGD and bimatoprost (a synthetic analogue of PGF).


title: Prostaglandin

text: There are currently ten known prostaglandin receptors on various cell types. Prostaglandins ligate a sub-family of cell surface seven-transmembrane receptors, G-protein-coupled receptors. These receptors are termed DP1-2, EP1-4, FP, IP1-2, and TP, corresponding to the receptor that ligates the corresponding prostaglandin (e.g., DP1-2 receptors bind to PGD2).


title: Prostaglandin

text: The diversity of receptors means that prostaglandins act on an array of cells and have a wide variety of effects such as:


title: Prostaglandin

text: The following is a comparison of different types of prostaglandin, including prostaglandin I (prostacyclin; PGI), prostaglandin D (PGD), prostaglandin E (PGE), and prostaglandin F (PGF).


title: Prostaglandin

text: The original synthesis of prostaglandins F2α and E2 is shown below. It involves a Diels–Alder reaction which establishes the relative stereochemistry of three contiguous stereocenters on the prostaglandin cyclopentane core.


title: Dies irae

text: "" (; "the Day of Wrath") is a Latin sequence attributed to either Thomas of Celano of the Franciscans (1200–1265) or to Latino Malabranca Orsini (d. 1294), lector at the Dominican at Santa Sabina, the forerunner of the Pontifical University of Saint Thomas Aquinas (the ) in Rome. The sequence dates from the 13th century at the latest, though it is possible that it is much older, with some sources ascribing its origin to St. Gregory the Great (d. 604), Bernard of Clairvaux (1090–1153), or Bonaventure (1221–1274).


title: Dies irae

text: It is a medieval Latin poem characterized by its accentual stress and rhymed lines. The metre is trochaic. The poem describes the Last Judgment, the trumpet summoning souls before the throne of God, where the saved will be delivered and the unsaved cast into eternal flames.


title: Dies irae

text: It is best known from its use in the Roman Rite Requiem (Mass for the Dead or Funeral Mass). An English version is found in various Anglican Communion service books.


title: Dies irae

text: The first melody set to these words, a Gregorian chant, is one of the most quoted in musical literature, appearing in the works of many composers. The final couplet, , has been often reused as an independent song.


title: Dies irae

text: The "" has been used in the Extraordinary Form of the Roman Rite liturgy as the sequence for the Requiem Mass for centuries, as made evident by the important place it holds in musical settings such as those by Mozart and Verdi. It appears in the Roman Missal of 1962, the last edition before the implementation of the revisions that occurred after the Second Vatican Council. As such, it is still heard in churches where the Tridentine Latin liturgy is celebrated. It also formed part of the pre-conciliar liturgy of All Souls' Day.


title: Dies irae

text: In the reforms to the Catholic Church’s Latin liturgical rites ordered by the Second Vatican Council, the "Consilium for the Implementation of the Constitution on the Liturgy", the Vatican body charged with drafting and implementing the reforms (1969–70), eliminated the sequence as such from funerals and other Masses for the Dead. A leading figure in the post-conciliar liturgical reforms, Archbishop Annibale Bugnini, explains the rationale of the Consilium:


title: Dies irae

text: "" remains as a hymn "ad libitum" in the Liturgy of the Hours during the last week before Advent, divided into three parts for the Office of Readings, Lauds and Vespers.


title: Dies irae

text: The Latin text below is taken from the Requiem Mass in the 1962 Roman Missal. The first English version below, translated by William Josiah Irons in 1849, albeit from a slightly different Latin text, replicates the rhyme and metre of the original. This translation, edited for more conformance to the official Latin, is approved by the Catholic Church for use as the funeral Mass sequence in the liturgy of the Anglican ordinariate. The second English version is a more formal equivalence translation.


title: Dies irae

text: Because the last two stanzas differ markedly in structure from the preceding stanzas, some scholars consider them to be an addition made in order to suit the great poem for liturgical use. The penultimate stanza, , discards the consistent scheme of rhyming triplets in favour of a pair of rhyming couplets. The last stanza, , abandons rhyme for assonance, and, moreover, its lines are catalectic.


title: Dies irae

text: In the liturgical reforms of 1969–71, stanza 19 was deleted and the poem divided into three sections: 1–6 (for Office of Readings), 7–12 (for Lauds) and 13–18 (for Vespers). In addition, in stanza 13 was replaced by so that that line would now mean, "You who absolved the sinful woman". This was because modern scholarship denies the common mediæval identification of the woman taken in adultery with Mary Magdalene, so Mary could no longer be named in this verse. In addition, a doxology is given after stanzas 6, 12 and 18:


title: Dies irae

text: The text of the sequence is found, with slight verbal variations, in a 13th-century manuscript in the Biblioteca Nazionale Vittorio Emanuele III at Naples. It is a Franciscan calendar missal that must date between 1253 and 1255 for it does not contain the name of Clare of Assisi, who was canonized in 1255, and whose name would have been inserted if the manuscript were of later date.


title: Dies irae

text: A major inspiration of the hymn seems to have come from the Vulgate translation of Zephaniah 1:15–16:


title: Dies irae

text: Other images come from the Book of Revelation, such as (the book from which the world will be judged), (sheep and goats, right hand, contrast between the blessed and the accursed doomed to flames), (trumpet), (heaven and earth burnt by fire), and ("men fainting with fear... they will see the Son of Man coming").


title: Dies irae

text: From the Jewish liturgy, the prayer Unetanneh Tokef appears to be related: "We shall ascribe holiness to this day, For it is awesome and terrible"; "the great trumpet is sounded", etc.


title: Dies irae

text: A number of English translations of the poem have been written and proposed for liturgical use. A very loose Protestant version was made by John Newton; it opens:


title: Dies irae

text: Jan Kasprowicz, a Polish poet, wrote a hymn entitled which describes the Judgment day. The first six lines (two stanzas) follow the original hymn's metre and rhyme structure, and the first stanza translates to "The trumpet will cast a wondrous sound".


title: Dies irae

text: The American writer Ambrose Bierce published a satiric version of the poem in his 1903 book "Shapes of Clay", preserving the original metre but using humorous and sardonic language; for example, the second verse is rendered:


title: Dies irae

text: The Rev. Bernard Callan (1750–1804), an Irish priest and poet, translated it into Gaelic around 1800. His version is included in a Gaelic prayer book, "The Spiritual Rose".


title: Dies irae

text: The words of "" have often been set to music as part of the Requiem service. In some settings, it is broken up into several movements; in such cases, "" refers only to the first of these movements, the others being titled according to their respective incipits.


title: Dies irae

text: The original setting was a sombre plainchant (or Gregorian chant). It is in the Dorian mode. In four-line neumatic notation, it begins:


title: Dies irae

text: The earliest surviving polyphonic setting of the Requiem by Johannes Ockeghem does not include "". The first polyphonic settings to include the "" are by Engarandus Juvenis (1490) and Antoine Brumel (1516) to be followed by many composers of the renaissance. Later, many notable choral and orchestral settings of the Requiem including the sequence were made by composers such as Mozart, Berlioz, Verdi, and Stravinsky. Giovanni Battista Martini ended his set of (mostly humorous) 303 canons with a set of 20 on extracts of the sequence poem.


title: Dies irae

text: The traditional Gregorian melody has been used as a theme or musical quotation in many classical compositions, including:


title: Emperor

text: An emperor (from , via ) is a monarch, and usually the sovereign ruler of an empire or another type of imperial realm. Empress, the female equivalent, may indicate an emperor's wife (empress consort), mother (empress dowager), or a woman who rules in her own right and name (empress regnant). Emperors are generally recognized to be of the highest monarchic honor and rank, surpassing kings. In Europe, the title of Emperor has been used since the Middle Ages, considered in those times equal or almost equal in dignity to that of Pope due to the latter's position as visible head of the Church and spiritual leader of the Catholic part of Western Europe. The Emperor of Japan is the only currently reigning monarch whose title is translated into English as "Emperor".


title: Emperor

text: Both emperors and kings are monarchs or sovereigns, but both emperor and empress are considered the higher monarchical titles. In as much as there is a strict definition of emperor, it is that an emperor has no relations implying the superiority of any other ruler and typically rules over more than one nation. Therefore, a king might be obliged to pay tribute to another ruler, or be restrained in his actions in some unequal fashion, but an emperor should in theory be completely free of such restraints. However, monarchs heading empires have not always used the title in all contexts—the British sovereign did not assume the title Empress of the British Empire even during the incorporation of India, though she was declared Empress of India.


title: Emperor

text: In Western Europe, the title of Emperor was used exclusively by the Holy Roman Emperor, whose imperial authority was derived from the concept of , i.e. they claimed succession to the authority of the Western Roman Emperors, thus linking themselves to Roman institutions and traditions as part of state ideology. Although initially ruling much of Central Europe and northern Italy, by the 19th century the Emperor exercised little power beyond the German-speaking states.


title: Emperor

text: Although technically an elective title, by the late 16th century the imperial title had in practice come to be inherited by the Habsburg Archdukes of Austria and following the Thirty Years' War their control over the states (outside the Habsburg monarchy, i.e. Austria, Bohemia and various territories outside the empire) had become nearly non-existent. However, Napoleon Bonaparte was crowned Emperor of the French in 1804 and was shortly followed by Francis II, Holy Roman Emperor, who declared himself Emperor of Austria in the same year. The position of Holy Roman Emperor nonetheless continued until Francis II abdicated that position in 1806. In Eastern Europe, the monarchs of Russia also used to wield imperial authority as successors to the Eastern Roman Empire. Their status was officially recognized by the Holy Roman Emperor in 1514, although not officially used by the Russian monarchs until 1547. However, the Russian emperors are better known by their Russian-language title of Tsar even after Peter the Great adopted the title of Emperor of All Russia in 1721.


title: Emperor

text: Historians have liberally used emperor and empire anachronistically and out of its Roman and European context to describe any large state from the past or the present. Such Pre-Roman titles as Great King or King of Kings, used by the Kings of Persia and others, are often considered as the equivalent. Sometimes this reference has even extended to non-monarchically ruled states and their spheres of influence such as the Athenian Empire of the late 5th century BC, the Angevin Empire of the Plantagenets and the Soviet and American "empires" of the Cold War era. However, such "empires" did not need to be headed by an "emperor". Empire became identified instead with vast territorial holdings rather than the title of its ruler by the mid-18th century.


title: Emperor

text: For purposes of protocol, emperors were once given precedence over kings in international diplomatic relations, but currently precedence among heads of state who are sovereigns—whether they be kings, queens, emperors, empresses, princes, princesses and, to a lesser degree, presidents—is determined by the duration of time that each one has been continuously in office. Outside the European context, emperor was the translation given to holders of titles who were accorded the same precedence as European emperors in diplomatic terms. In reciprocity, these rulers might accredit equal titles in their native languages to their European peers. Through centuries of international convention, this has become the dominant rule to identifying an emperor in the modern era.


title: Emperor

text: When Republican Rome turned into a "de facto" monarchy in the second half of the 1st century BC, at first there was no name for the title of the new type of monarch. Ancient Romans abhorred the name Rex ("king"), and it was critical to the political order to maintain the forms and pretenses of republican rule. Julius Caesar had been Dictator, an acknowledged and traditional office in Republican Rome. Caesar was not the first to hold it, but following his assassination the term was abhorred in Rome.


title: Emperor

text: Augustus, considered the first Roman emperor, established his hegemony by collecting on himself offices, titles, and honours of Republican Rome that had traditionally been distributed to different people, concentrating what had been distributed power in one man. One of these offices was "princeps senatus", ("first man of the Senate") and became changed into Augustus' chief honorific, "princeps civitatis" ("first citizen") from which the modern English word and title prince is descended. The first period of the Roman Empire, from 27 BC – AD 284, is called the "principate" for this reason. However, it was the informal descriptive of "Imperator" ("commander") that became the title increasingly favored by his successors. Previously bestowed on high officials and military commanders who had "imperium", Augustus reserved it exclusively to himself as the ultimate holder of all "imperium". ("Imperium" is Latin for the authority to command, one of a various types of authority delineated in Roman political thought.)


title: Emperor

text: Beginning with Augustus, "Imperator" appeared in the title of all Roman monarchs through the extinction of the Empire in 1453. After the reign of Augustus' immediate successor Tiberius, being proclaimed "imperator" was transformed into the act of accession to the head of state. Other honorifics used by the Roman Emperors have also come to be synonyms for Emperor:


title: Emperor

text: After the turbulent Year of the four emperors in 69, the Flavian Dynasty reigned for three decades. The succeeding Nervan-Antonian Dynasty, ruling for most of the 2nd century, stabilised the Empire. This epoch became known as the era of the "Five Good Emperors", and was followed by the short-lived Severan Dynasty.


title: Emperor

text: During the Crisis of the 3rd century, Barracks Emperors succeeded one another at short intervals. Three short lived secessionist attempts had their own emperors: the Gallic Empire, the Britannic Empire, and the Palmyrene Empire though the latter used "rex" more regularly.


title: Emperor

text: The Principate (27 BC – 284 AD) period was succeeded by what is known as the Dominate (284 AD – 527 AD), during which Emperor Diocletian tried to put the Empire on a more formal footing. Diocletian sought to address the challenges of the Empire's now vast geography and the instability caused by the informality of succession by the creation of co-emperors and junior emperors. At one point, there were as many as five sharers of the "imperium" (see: Tetrarchy). In 325 AD Constantine I defeated his rivals and restored single emperor rule, but following his death the empire was divided among his sons. For a time the concept was of one empire ruled by multiple emperors with varying territory under their control, however following the death of Theodosius I the rule was divided between his two sons and increasingly became separate entities. The areas administered from Rome are referred to by historians the Western Roman Empire and those under the immediate authority of Constantinople called the Eastern Roman Empire or (after the Battle of Yarmouk in 636 AD) the Later Roman or Byzantine Empire. The subdivisions and co-emperor system were formally abolished by Emperor Zeno in 480 AD following the death of Julius Nepos last Western Emperor and the ascension of Odoacer as the "de facto" King of Italy in 476 AD.


title: Emperor

text: Historians generally refer to the continuing Roman Empire in the east as the Byzantine Empire after Byzantium, the original name of the town that Constantine I would elevate to the Imperial capital as New Rome in AD 330. (The city is more commonly called Constantinople and is today named Istanbul). Although the empire was again subdivided and a co-emperor sent to Italy at the end of the fourth century, the office became unitary again only 95 years later at the request of the Roman Senate and following the death of Julius Nepos, last Western Emperor. This change was a recognition of the reality that little remained of Imperial authority in the areas that had been the Western Empire, with even Rome and Italy itself now ruled by the essentially autonomous Odoacer.


title: Emperor

text: These Later Roman "Byzantine" Emperors completed the transition from the idea of the Emperor as a semi-republican official to the Emperor as an absolute monarch. Of particular note was the translation of the Latin "Imperator" into the Greek "Basileus", after Emperor Heraclius changed the official language of the empire from Latin to Greek in AD 620. Basileus, a title which had long been used for Alexander the Great was already in common usage as the Greek word for the Roman emperor, but its definition and sense was "King" in Greek, essentially equivalent with the Latin "Rex". Byzantine period emperors also used the Greek word "autokrator", meaning "one who rules himself", or "monarch", which was traditionally used by Greek writers to translate the Latin "dictator". Essentially, the Greek language did not incorporate the nuances of the Ancient Roman concepts that distinguished "imperium" from other forms of political power.


title: Emperor

text: In general usage, the Byzantine imperial title evolved from simply "emperor" ("basileus"), to "emperor of the Romans" ("basileus tōn Rōmaiōn") in the 9th century, to "emperor and autocrat of the Romans" ("basileus kai autokratōr tōn Rōmaiōn") in the 10th. In fact, none of these (and other) additional epithets and titles had ever been completely discarded.


title: Emperor

text: One important distinction between the post Constantine I (reigned AD 306–337) emperors and their pagan predecessors was cesaropapism, the assertion that the Emperor (or other head of state) is also the head of the Church. Although this principle was held by all emperors after Constantine, it met with increasing resistance and ultimately rejection by bishops in the west after the effective end of Imperial power there. This concept became a key element of the meaning of "emperor" in the Byzantine and Orthodox east, but went out of favor in the west with the rise of Roman Catholicism.


title: Emperor

text: The Byzantine Empire also produced three women who effectively governed the state: the Empress Irene and the Empresses Zoe and Theodora.


title: Emperor

text: In 1204 Constantinople fell to the Venetians and the Franks in the Fourth Crusade. Following the tragedy of the horrific sacking of the city, the conquerors declared a new "Empire of Romania", known to historians as the Latin Empire of Constantinople, installing Baldwin IX, Count of Flanders, as Emperor. However, Byzantine resistance to the new empire meant that it was in constant struggle to establish itself. Byzantine Emperor Michael VIII Palaiologos succeeded in recapturing Constantinople in 1261. The Principality of Achaea, a vassal state the empire had created in Morea (Greece) intermittently continued to recognize the authority of the crusader emperors for another half century. Pretenders to the title continued among the European nobility until circa 1383.