The focal length of an optical system is a measure of how the system converges or diverges light. For an optical system in air, it is the distance over which collimated rays are brought to a focus. A system with a shorter focal length has greater optical power than one with a long focal length. In most photography and all telescopy, where the subject is infinitely far away, longer focal length leads to higher magnification and a narrower angle of view. On the other hand, in applications such as microscopy in which magnification is achieved by bringing the object close to the lens, a shorter focal length leads to higher magnification because the subject can be brought closer to the center of projection. For a thin lens in air, the focal length is the distance from the center of the lens to the principal foci of the lens. For a converging lens, the focal length is positive, is the distance at which a beam of collimated light will be focused to a single spot. For a diverging lens, the focal length is negative, is the distance to the point from which a collimated beam appears to be diverging after passing through the lens.
When a lens is used to form an image of some object, the distance from the object to the lens u, the distance from the lens to the image v, the focal length f are related by 1 f = 1 u + 1 v. The focal length of a thin lens can be measured by using it to form an image of a distant light source on a screen; the lens is moved. In this case 1/u is negligible, the focal length is given by f ≈ v. For a thick lens, or an imaging system consisting of several lenses or mirrors, the focal length is called the effective focal length, to distinguish it from other used parameters: Front focal length or front focal distance is the distance from the front focal point of the system to the vertex of the first optical surface. Back focal length or back focal distance is the distance from the vertex of the last optical surface of the system to the rear focal point. For an optical system in air, the effective focal length gives the distance from the front and rear principal planes to the corresponding focal points.
If the surrounding medium is not air the distance is multiplied by the refractive index of the medium. Some authors call these distances the front/rear focal lengths, distinguishing them from the front/rear focal distances, defined above. In general, the focal length or EFL is the value that describes the ability of the optical system to focus light, is the value used to calculate the magnification of the system; the other parameters are used in determining where an image will be formed for a given object position. For the case of a lens of thickness d in air, surfaces with radii of curvature R1 and R2, the effective focal length f is given by the Lensmaker's equation: 1 f =, where n is the refractive index of the lens medium; the quantity 1/f is known as the optical power of the lens. The corresponding front focal distance is: FFD = f, the back focal distance: BFD = f. In the sign convention used here, the value of R1 will be positive if the first lens surface is convex, negative if it is concave.
The value of R2 is negative if the second surface is convex, positive if concave. Note that sign conventions vary between different authors, which results in different forms of these equations depending on the convention used. For a spherically curved mirror in air, the magnitude of the focal length is equal to the radius of curvature of the mirror divided by two; the focal length is positive for a concave mi
Athanasius Kircher, S. J. was a German Jesuit scholar and polymath who published around 40 major works, most notably in the fields of comparative religion and medicine. Kircher has been compared to fellow Jesuit Roger Boscovich and to Leonardo da Vinci for his enormous range of interests, has been honored with the title "Master of a Hundred Arts", he taught for more than forty years at the Roman College. A resurgence of interest in Kircher has occurred within the scholarly community in recent decades. Kircher claimed to have deciphered the hieroglyphic writing of the ancient Egyptian language, but most of his assumptions and translations in this field were found to be incorrect, he did, however establish the link between the ancient Egyptian and the Coptic languages, some commentators regard him as the founder of Egyptology. Kircher was fascinated with Sinology and wrote an encyclopedia of China, in which he noted the early presence there of Nestorian Christians while attempting to establish links with Egypt and Christianity.
Kircher's work in geology included studies of fossils. One of the first people to observe microbes through a microscope, Kircher was ahead of his time in proposing that the plague was caused by an infectious microorganism and in suggesting effective measures to prevent the spread of the disease. Kircher displayed a keen interest in technology and mechanical inventions; the invention of the magic lantern is misattributed to Kircher, although he did conduct a study of the principles involved in his Ars Magna Lucis et Umbrae. A scientific star in his day, towards the end of his life he was eclipsed by the rationalism of René Descartes and others. In the late 20th century, the aesthetic qualities of his work again began to be appreciated. One modern scholar, Alan Cutler, described Kircher as "a giant among seventeenth-century scholars", "one of the last thinkers who could rightfully claim all knowledge as his domain". Another scholar, Edward W. Schmidt, referred to Kircher as "the last Renaissance man".
In A Man of Misconceptions, his 2012 book about Kircher, John Glassie writes that while "many of Kircher's actual ideas today seem wildly off-base, if not bizarre," he was "a champion of wonder, a man of awe-inspiring erudition and inventiveness," whose work was read "by the smartest minds of the time." Kircher was born on 2 May in either 1601 or 1602 in Geisa, near Fulda Hesse, Germany. From his birthplace he took the epithets Bucho and Fuldensis which he sometimes added to his name, he attended the Jesuit College in Fulda from 1614 to 1618, when he entered the novitiate of the Society. The youngest of nine children, Kircher studied volcanoes owing to his passion for rocks and eruptions, he was taught Hebrew by a rabbi in addition to his studies at school. He studied philosophy and theology at Paderborn, but fled to Cologne in 1622 to escape advancing Protestant forces. On the journey, he narrowly escaped death after falling through the ice crossing the frozen Rhine — one of several occasions on which his life was endangered.
Traveling to Heiligenstadt, he was caught and nearly hanged by a party of Protestant soldiers. From 1622 to 1624 Kircher was sent to begin his regency period in Koblenz as a teacher; this was followed by his assignment to Heiligenstadt, where he taught mathematics and Syriac, produced a show of fireworks and moving scenery for the visiting Elector Archbishop of Mainz, showing early evidence of his interest in mechanical devices. He was ordained to the priesthood in 1628 and became professor of ethics and mathematics at the University of Würzburg, where he taught Hebrew and Syriac. Beginning in 1628, he began to show an interest in Egyptian hieroglyphs. In 1631, while still at Würzburg, Kircher had a prophetic vision of bright light and armed men with horses in the city. Wurzburg was shortly afterwards attacked and captured, leading to Kircher being accorded respect for predicting the disaster via astrology, though Kircher himself insisted that he had not relied on that art; this was the year that Kircher published his first book, but having been caught up in the Thirty Years' War he was driven to the papal University of Avignon in France.
In 1633 he was called to Vienna by the emperor to succeed Kepler as Mathematician to the Habsburg court. On the intervention of Nicolas-Claude Fabri de Peiresc, the order was rescinded, he was sent instead to Rome to continue with his scholarly work, but he had embarked for Vienna. On the way, his ship was blown off course and he arrived in Rome before he knew of the changed decision, he based himself in the city for the rest of his life, from 1634 he taught mathematics and Oriental languages at the Collegio Romano for several years before being released to devote himself to research. He studied malaria and the plague, amassing a collection of antiquities, which he exhibited along with devices of his own creation in the Museum Kircherianum. In 1661, Kircher discovered the ruins of a church said to have been constructed by Constantine on the site of Saint Eustace's vision of Jesus Christ in a stag's horns, he raised money to pay for the church's reconstruction as the Santuario della Mentorella, his heart was buried in the church on his death.
Kircher published a large number of substantial books on a wide variety of subjects, such as Egyptology and music th
France the French Republic, is a country whose territory consists of metropolitan France in Western Europe and several overseas regions and territories. The metropolitan area of France extends from the Mediterranean Sea to the English Channel and the North Sea, from the Rhine to the Atlantic Ocean, it is bordered by Belgium and Germany to the northeast and Italy to the east, Andorra and Spain to the south. The overseas territories include French Guiana in South America and several islands in the Atlantic and Indian oceans; the country's 18 integral regions span a combined area of 643,801 square kilometres and a total population of 67.3 million. France, a sovereign state, is a unitary semi-presidential republic with its capital in Paris, the country's largest city and main cultural and commercial centre. Other major urban areas include Lyon, Toulouse, Bordeaux and Nice. During the Iron Age, what is now metropolitan France was inhabited by a Celtic people. Rome annexed the area in 51 BC, holding it until the arrival of Germanic Franks in 476, who formed the Kingdom of Francia.
The Treaty of Verdun of 843 partitioned Francia into Middle Francia and West Francia. West Francia which became the Kingdom of France in 987 emerged as a major European power in the Late Middle Ages following its victory in the Hundred Years' War. During the Renaissance, French culture flourished and a global colonial empire was established, which by the 20th century would become the second largest in the world; the 16th century was dominated by religious civil wars between Protestants. France became Europe's dominant cultural and military power in the 17th century under Louis XIV. In the late 18th century, the French Revolution overthrew the absolute monarchy, established one of modern history's earliest republics, saw the drafting of the Declaration of the Rights of Man and of the Citizen, which expresses the nation's ideals to this day. In the 19th century, Napoleon established the First French Empire, his subsequent Napoleonic Wars shaped the course of continental Europe. Following the collapse of the Empire, France endured a tumultuous succession of governments culminating with the establishment of the French Third Republic in 1870.
France was a major participant in World War I, from which it emerged victorious, was one of the Allies in World War II, but came under occupation by the Axis powers in 1940. Following liberation in 1944, a Fourth Republic was established and dissolved in the course of the Algerian War; the Fifth Republic, led by Charles de Gaulle, remains today. Algeria and nearly all the other colonies became independent in the 1960s and retained close economic and military connections with France. France has long been a global centre of art and philosophy, it hosts the world's fourth-largest number of UNESCO World Heritage Sites and is the leading tourist destination, receiving around 83 million foreign visitors annually. France is a developed country with the world's sixth-largest economy by nominal GDP, tenth-largest by purchasing power parity. In terms of aggregate household wealth, it ranks fourth in the world. France performs well in international rankings of education, health care, life expectancy, human development.
France is considered a great power in global affairs, being one of the five permanent members of the United Nations Security Council with the power to veto and an official nuclear-weapon state. It is a leading member state of the European Union and the Eurozone, a member of the Group of 7, North Atlantic Treaty Organization, Organisation for Economic Co-operation and Development, the World Trade Organization, La Francophonie. Applied to the whole Frankish Empire, the name "France" comes from the Latin "Francia", or "country of the Franks". Modern France is still named today "Francia" in Italian and Spanish, "Frankreich" in German and "Frankrijk" in Dutch, all of which have more or less the same historical meaning. There are various theories as to the origin of the name Frank. Following the precedents of Edward Gibbon and Jacob Grimm, the name of the Franks has been linked with the word frank in English, it has been suggested that the meaning of "free" was adopted because, after the conquest of Gaul, only Franks were free of taxation.
Another theory is that it is derived from the Proto-Germanic word frankon, which translates as javelin or lance as the throwing axe of the Franks was known as a francisca. However, it has been determined that these weapons were named because of their use by the Franks, not the other way around; the oldest traces of human life in what is now France date from 1.8 million years ago. Over the ensuing millennia, Humans were confronted by a harsh and variable climate, marked by several glacial eras. Early hominids led a nomadic hunter-gatherer life. France has a large number of decorated caves from the upper Palaeolithic era, including one of the most famous and best preserved, Lascaux. At the end of the last glacial period, the climate became milder. After strong demographic and agricultural development between the 4th and 3rd millennia, metallurgy appeared at the end of the 3rd millennium working gold and bronze, iron. France has numerous megalithic sites from the Neolithic period, including the exceptiona
An observatory is a location used for observing terrestrial or celestial events. Astronomy, climatology/meteorology, geophysical and volcanology are examples of disciplines for which observatories have been constructed. Observatories were as simple as containing an astronomical sextant or Stonehenge. Astronomical observatories are divided into four categories: space-based, ground-based, underground-based. Ground-based observatories, located on the surface of Earth, are used to make observations in the radio and visible light portions of the electromagnetic spectrum. Most optical telescopes are housed within a dome or similar structure, to protect the delicate instruments from the elements. Telescope domes have a slit or other opening in the roof that can be opened during observing, closed when the telescope is not in use. In most cases, the entire upper portion of the telescope dome can be rotated to allow the instrument to observe different sections of the night sky. Radio telescopes do not have domes.
For optical telescopes, most ground-based observatories are located far from major centers of population, to avoid the effects of light pollution. The ideal locations for modern observatories are sites that have dark skies, a large percentage of clear nights per year, dry air, are at high elevations. At high elevations, the Earth's atmosphere is thinner, thereby minimizing the effects of atmospheric turbulence and resulting in better astronomical "seeing". Sites that meet the above criteria for modern observatories include the southwestern United States, Canary Islands, the Andes, high mountains in Mexico such as Sierra Negra. A newly emerging site which should be added to this list is Mount Gargash. With an elevation of 3600 m above sea level, it is the home to the Iranian National Observatory and its 3.4m INO340 telescope. Major optical observatories include Mauna Kea Observatory and Kitt Peak National Observatory in the US, Roque de los Muchachos Observatory and Calar Alto Observatory in Spain, Paranal Observatory in Chile.
Specific research study performed in 2009 shows that the best possible location for ground-based observatory on Earth is Ridge A — a place in the central part of Eastern Antarctica. This location provides the least atmospheric disturbances and best visibility. Beginning in 1930s, radio telescopes have been built for use in the field of radio astronomy to observe the Universe in the radio portion of the electromagnetic spectrum; such an instrument, or collection of instruments, with supporting facilities such as control centres, visitor housing, data reduction centers, and/or maintenance facilities are called radio observatories. Radio observatories are located far from major population centers to avoid electromagnetic interference from radio, TV, other EMI emitting devices, but unlike optical observatories, radio observatories can be placed in valleys for further EMI shielding; some of the world's major radio observatories include the Socorro, in New Mexico, United States, Jodrell Bank in the UK, Arecibo in Puerto Rico, Parkes in New South Wales and Chajnantor in Chile.
Since the mid-20th century, a number of astronomical observatories have been constructed at high altitudes, above 4,000–5,000 m. The largest and most notable of these is the Mauna Kea Observatory, located near the summit of a 4,205 m volcano in Hawaiʻi; the Chacaltaya Astrophysical Observatory in Bolivia, at 5,230 m, was the world's highest permanent astronomical observatory from the time of its construction during the 1940s until 2009. It has now been surpassed by the new University of Tokyo Atacama Observatory, an optical-infrared telescope on a remote 5,640 m mountaintop in the Atacama Desert of Chile; the oldest proto-observatories, in the sense of a private observation post, Wurdi Youang, Australia Zorats Karer, Armenia Loughcrew, Ireland Newgrange, Ireland Stonehenge, Great Britain Quito Astronomical Observatory, located 12 minutes south of the Equator in Quito, Ecuador. Chankillo, Peru El Caracol, Mexico Abu Simbel, Egypt Kokino, Republic of Macedonia Observatory at Rhodes, Greece Goseck circle, Germany Ujjain, India Arkaim, Russia Cheomseongdae, South Korea Angkor Wat, CambodiaThe oldest true observatories, in the sense of a specialized research institute, include: 825 AD: Al-Shammisiyyah observatory, Iraq 869: Mahodayapuram Observatory, India 1259: Maragheh observatory, Iran 1276: Gaocheng Astronomical Observatory, China 1420: Ulugh Beg Observatory, Uzbekistan 1442: Beijing Ancient Observatory, China 1577: Constantinople Observatory of Taqi ad-Din, Turkey 1580: Uraniborg, Denmark 1581: Stjerneborg, Denmark 1642: Panzano Observatory, Italy 1642: Round Tower, Denmark 1633: Leiden Observatory, Netherlands 1667: Paris Observatory, France 1675: Royal Greenwich Observatory, England 1695: Sukharev Tower, Russia 1711: Berlin Observatory, Germany 1724: Jantar Mantar, India 1753: Stockholm Observatory, Sweden 1753: Vilnius University Observatory, Lithuania 1753: Navy Royal Institute and Observatory, Spain 1759: Trieste Observatory, Italy 1757: Macfarlane Observatory, Scotland 1759: Turin Observatory, Italy 1764: Brera Astronomical Observatory, Italy 1765: Mohr Observatory, Indonesia 1774: Vatican Observatory, Vatican 1785: Dunsink Observatory, Ireland 1786: Madras Observatory, India 1789: Armagh Observatory, Northern Ireland 1790: Real Observatorio de Madrid, Spain, 1803: National Astronomical Observatory, Bogotá, Colombia.
1811: Tartu Old Observatory, Estonia 1812: Astronomical Observatory of Capodimonte, Italy 1830/1842: Depot of Charts & Instruments
A quadrant is an instrument, used to measure angles up to 90°. Different versions of this instrument could be used to calculate various readings, such as longitude and time of day, it was proposed by Ptolemy as a better kind of astrolabe. Several different variations of the instrument were produced by medieval Muslim astronomers; the term “quadrant”, meaning one fourth, refers to the fact that early versions of the instrument were derived from astrolabes. The quadrant condensed the workings of the astrolabe into an area one fourth the size of the astrolabe face. One of the earliest accounts of a quadrant comes from Ptolemy's Almagest around AD 150, he described a “plinth” that could measure the altitude of the noon sun by projecting the shadow of a peg on a graduated arc of 90 degrees. This quadrant was unlike versions of the instrument. Ptolemy's version was a derivative of the astrolabe and the purpose of this rudimentary device was to measure the meridian angle of the sun. Islamic astronomers in the Middle Ages improved upon these ideas and constructed quadrants throughout the Middle East, in observatories such as Marageh and Samarkand.
At first these quadrants were very large and stationary, could be rotated to any bearing to give both the altitude and azimuth for any celestial body. As Islamic astronomers made advancements in astronomical theory and observational accuracy they are credited with developing four different types of quadrants during the Middle Ages and beyond; the first of these, the sine quadrant, was invented by Muhammad ibn Musa al-Khwarizmi in the 9th century at the House of Wisdom in Baghdad. The other types were the horary quadrant and the astrolabe quadrant. During the Middle Ages the knowledge of these instruments spread to Europe. In the 13th century Jewish astronomer Jacob ben Machir ibn Tibbon was crucial in further developing the quadrant, he was a skilled astronomer and wrote several volumes on the topic, including an influential book detailing how to build and use an improved version of the quadrant. The quadrant that he invented came to be known as new quadrant; this device was revolutionary because it was the first quadrant to be built that did not involve several moving parts and thus could be much smaller and more portable.
Tibbon's Hebrew manuscripts were translated into Latin and improved upon by French scholar Peter Nightingale several years later. Because of the translation, Tibbon, or Prophatius Judaeus as he was known in Latin, became an influential name in astronomy, his new quadrant was based upon the idea that the stereographic projection that defines a planispheric astrolabe can still work if the astrolabe parts are folded into a single quadrant. The result was a device, far cheaper, easier to use and more portable than a standard astrolabe. Tibbon's work influenced Copernicus, Christopher Clavius and Erasmus Reinhold; as the quadrant became smaller and thus more portable, its value for navigation was soon realized. The first documented use of the quadrant to navigate at sea is by Diogo Gomes. Sailors began by measuring the height of Polaris to ascertain their latitude; this application of quadrants is attributed to Arab sailors who traded along the east coast of Africa and travelled out of sight of land.
It soon became more common to take the height of the sun at a given time due to the fact that Polaris disappears south of the equator. In 1618 English Mathematician Edmund Gunter further adapted the quadrant with an invention that came to be known as the Gunter quadrant; this pocket sized quadrant was revolutionary because it was inscribed with projections of the tropics, the equator, the horizon and the ecliptic. With the correct tables one could use the quadrant to find the time, the date, the length of the day or night, the time of sunrise and sunset and the meridian; the Gunter quadrant was useful but it had its drawbacks. There are several types of quadrants: Mural quadrants, used for determining the time by measuring the altitudes of altitudes of astronomical objects. Tycho Brahe created one of the largest mural quadrants. In order to tell time he would place two clocks next to the quadrant so that he could identify the minutes and seconds in relation to the measurements on the side of the instrument.
Large frame-based instruments used for measuring angular distances between astronomical objects. Geometric quadrant used by navigators. Davis quadrant a compact, framed instrument used by navigators for measuring the altitude of an astronomical object, they can be classified as: Altitude – The plain quadrant with plumb line, used to take the altitude of an object. Gunner's – A type of clinometer used by an artillerist to measure the elevation or depression angle of a gun barrel of a cannon or mortar, both to verify proper firing elevation, to verify the correct alignment of the weapon-mounted fire control devices. Gunter's – A quadrant used for time determination as well as the length of day, when the sun had risen and set, the date, the meridian using scales and curves of the quadrant along with related tables, it was invented by Edmund Gunter in 1623. Gunter's quadrant was simple which allowed for its widespread and long-lasting use in the 17th and 18th centuries. Gunter expanded the basic features of other quadrants to create a convenient and comprehensive instrument.
Its distinguishable feature included projections of the tropics, equator and the horizon. Islamic – King identifi
Brewing is the production of beer by steeping a starch source in water and fermenting the resulting sweet liquid with yeast. It may be done in a brewery by a commercial brewer, at home by a homebrewer, or by a variety of traditional methods such as communally by the indigenous peoples in Brazil when making cauim. Brewing has taken place since around the 6th millennium BC, archaeological evidence suggests that emerging civilizations including ancient Egypt and Mesopotamia brewed beer. Since the nineteenth century the brewing industry has been part of most western economies; the basic ingredients of beer are a fermentable starch source such as malted barley. Most beer is flavoured with hops. Less used starch sources include millet and cassava. Secondary sources, such as maize, rice, or sugar, may be used, sometimes to reduce cost, or to add a feature, such as adding wheat to aid in retaining the foamy head of the beer; the proportion of each starch source in a beer recipe is collectively called the grain bill.
Steps in the brewing process include malting, mashing, boiling, conditioning and packaging. There are three main fermentation methods, warm and spontaneous. Fermentation may take place in an closed fermenting vessel. There are several additional brewing methods, such as barrel aging, double dropping, Yorkshire Square. Brewing has taken place since around the 6th millennium BC, archaeological evidence suggests emerging civilizations including ancient Egypt and Mesopotamia brewed beer. Descriptions of various beer recipes can be found in cuneiform from ancient Mesopotamia. In Mesopotamia the brewer's craft was the only profession which derived social sanction and divine protection from female deities/goddesses, specifically: Ninkasi, who covered the production of beer, used in a metonymic way to refer to beer, Siduri, who covered the enjoyment of beer. In pre-industrial times, in developing countries, women are the main brewers; as any cereal containing certain sugars can undergo spontaneous fermentation due to wild yeasts in the air, it is possible that beer-like beverages were independently developed throughout the world soon after a tribe or culture had domesticated cereal.
Chemical tests of ancient pottery jars reveal that beer was produced as far back as about 7,000 years ago in what is today Iran. This discovery reveals one of the earliest known uses of fermentation and is the earliest evidence of brewing to date. In Mesopotamia, the oldest evidence of beer is believed to be a 6,000-year-old Sumerian tablet depicting people drinking a beverage through reed straws from a communal bowl. A 3900-year-old Sumerian poem honouring Ninkasi, the patron goddess of brewing, contains the oldest surviving beer recipe, describing the production of beer from barley via bread; the invention of bread and beer has been argued to be responsible for humanity's ability to develop technology and build civilization. The earliest chemically confirmed barley beer to date was discovered at Godin Tepe in the central Zagros Mountains of Iran, where fragments of a jug, at least 5,000 years old was found to be coated with beerstone, a by-product of the brewing process. Beer may have been known in Neolithic Europe as far back as 5,000 years ago, was brewed on a domestic scale.
Ale produced before the Industrial Revolution continued to be made and sold on a domestic scale, although by the 7th century AD beer was being produced and sold by European monasteries. During the Industrial Revolution, the production of beer moved from artisanal manufacture to industrial manufacture, domestic manufacture ceased to be significant by the end of the 19th century; the development of hydrometers and thermometers changed brewing by allowing the brewer more control of the process, greater knowledge of the results. Today, the brewing industry is a global business, consisting of several dominant multinational companies and many thousands of smaller producers ranging from brewpubs to regional breweries. More than 133 billion litres are sold per year—producing total global revenues of $294.5 billion in 2006. The basic ingredients of beer are water. A mixture of starch sources may be used, with a secondary saccharide, such as maize, rice, or sugar being termed an adjunct when used as a lower-cost substitute for malted barley.
Less used starch sources include millet and cassava root in Africa, potato in Brazil, agave in Mexico, among others. The amount of each starch source in a beer recipe is collectively called the grain bill. WaterBeer is composed of water. Regions have water with different mineral components. For example, Dublin has hard water well suited to making stout, such as Guinness; the waters of Burton in England contain gypsum, which benefits making pale ale to such a degree that brewers of pale ales will add gypsum to the local water in a process known as Burtonisation. Starch source The starch source in a beer provides the fermentable material and is a key determinant of the strength and flavour of the beer; the most common starch source used in bee
England is a country, part of the United Kingdom. It shares land borders with Wales to Scotland to the north-northwest; the Irish Sea lies west of England and the Celtic Sea lies to the southwest. England is separated from continental Europe by the North Sea to the east and the English Channel to the south; the country covers five-eighths of the island of Great Britain, which lies in the North Atlantic, includes over 100 smaller islands, such as the Isles of Scilly and the Isle of Wight. The area now called England was first inhabited by modern humans during the Upper Palaeolithic period, but takes its name from the Angles, a Germanic tribe deriving its name from the Anglia peninsula, who settled during the 5th and 6th centuries. England became a unified state in the 10th century, since the Age of Discovery, which began during the 15th century, has had a significant cultural and legal impact on the wider world; the English language, the Anglican Church, English law – the basis for the common law legal systems of many other countries around the world – developed in England, the country's parliamentary system of government has been adopted by other nations.
The Industrial Revolution began in 18th-century England, transforming its society into the world's first industrialised nation. England's terrain is chiefly low hills and plains in central and southern England. However, there is upland and mountainous terrain in the west; the capital is London, which has the largest metropolitan area in both the United Kingdom and the European Union. England's population of over 55 million comprises 84% of the population of the United Kingdom concentrated around London, the South East, conurbations in the Midlands, the North West, the North East, Yorkshire, which each developed as major industrial regions during the 19th century; the Kingdom of England – which after 1535 included Wales – ceased being a separate sovereign state on 1 May 1707, when the Acts of Union put into effect the terms agreed in the Treaty of Union the previous year, resulting in a political union with the Kingdom of Scotland to create the Kingdom of Great Britain. In 1801, Great Britain was united with the Kingdom of Ireland to become the United Kingdom of Great Britain and Ireland.
In 1922 the Irish Free State seceded from the United Kingdom, leading to the latter being renamed the United Kingdom of Great Britain and Northern Ireland. The name "England" is derived from the Old English name Englaland, which means "land of the Angles"; the Angles were one of the Germanic tribes that settled in Great Britain during the Early Middle Ages. The Angles came from the Anglia peninsula in the Bay of Kiel area of the Baltic Sea; the earliest recorded use of the term, as "Engla londe", is in the late-ninth-century translation into Old English of Bede's Ecclesiastical History of the English People. The term was used in a different sense to the modern one, meaning "the land inhabited by the English", it included English people in what is now south-east Scotland but was part of the English kingdom of Northumbria; the Anglo-Saxon Chronicle recorded that the Domesday Book of 1086 covered the whole of England, meaning the English kingdom, but a few years the Chronicle stated that King Malcolm III went "out of Scotlande into Lothian in Englaland", thus using it in the more ancient sense.
According to the Oxford English Dictionary, its modern spelling was first used in 1538. The earliest attested reference to the Angles occurs in the 1st-century work by Tacitus, Germania, in which the Latin word Anglii is used; the etymology of the tribal name itself is disputed by scholars. How and why a term derived from the name of a tribe, less significant than others, such as the Saxons, came to be used for the entire country and its people is not known, but it seems this is related to the custom of calling the Germanic people in Britain Angli Saxones or English Saxons to distinguish them from continental Saxons of Old Saxony between the Weser and Eider rivers in Northern Germany. In Scottish Gaelic, another language which developed on the island of Great Britain, the Saxon tribe gave their name to the word for England. An alternative name for England is Albion; the name Albion referred to the entire island of Great Britain. The nominally earliest record of the name appears in the Aristotelian Corpus the 4th-century BC De Mundo: "Beyond the Pillars of Hercules is the ocean that flows round the earth.
In it are two large islands called Britannia. But modern scholarly consensus ascribes De Mundo not to Aristotle but to Pseudo-Aristotle, i.e. it was written in the Graeco-Roman period or afterwards. The word Albion or insula Albionum has two possible origins, it either derives from a cognate of the Latin albus meaning white, a reference to the white cliffs of Dover or from the phrase the "island of the Albiones" in the now lost Massaliote Periplus, attested through Avienus' Ora Maritima to which the former served as a source. Albion is now applied to England in a more poetic capacity. Another romantic name for England is Loegria, related to the Welsh word for England and made popular by its use in Arthurian legend; the earliest known evidence of human presence in the area now known as England was that of Homo antecessor, dating to approximate