1.
Ordnance Survey
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Ordnance Survey is a non-ministerial government department which acts as the national mapping agency for Great Britain and is one of the worlds largest producers of maps. Since 1 April 2015 it has operated as Ordnance Survey Ltd, the Ordnance Survey Board remain accountable to the Secretary of State for Business, Energy and Industrial Strategy. It is also a member of the Public Data Group, the agencys name indicates its original military purpose, mapping Scotland in the wake of the Jacobite rebellion in 1745. There was also a general and nationwide need in light of the potential threat of invasion during the Napoleonic Wars. Ordnance Survey mapping is usually classified as either large-scale or small-scale, the Surveys large-scale mapping comprises maps at six inches to the mile or more and was available as sheets until the 1980s, when it was digitised. Small-scale mapping comprises maps at less than six inches to the mile, such as the one inch to the mile leisure maps. These are still available in sheet form. Ordnance Survey maps remain in copyright for fifty years after their publication, some of the Copyright Libraries hold complete or near-complete collections of pre-digital OS mapping. The origins of the Ordnance Survey lie in the aftermath of the last Jacobite rising which was defeated by forces loyal to the government at the Battle of Culloden in 1746. In 1747, Lieutenant-colonel David Watson proposed the compilation of a map of the Highlands to facilitate the subjugation of clans, in response, King George II charged Watson with making a military survey of the Highlands under the command of the Duke of Cumberland. Among Watsons assistants were William Roy, Paul Sandby and John Manson, the survey was produced at a scale of 1 inch to 1000 yards and included the Duke of Cumberlands Map now held in the British Library. This work was the point of the Principal Triangulation of Great Britain. Roys technical skills and leadership set the standard for which Ordnance Survey became known. Work was begun in earnest in 1790 under Roys supervision, when the Board of Ordnance began a military survey starting with the south coast of England. A set of stamps, featuring maps of the Kentish village of Hamstreet, was issued in 1991 to mark the bicentenary. In 1801, the first one-inch-to-the-mile map was published, detailing the county of Kent, during the next twenty years, roughly a third of England and Wales was mapped at the same scale under the direction of William Mudge, as other military matters took precedence. It took until 1823 to re-establish a relationship with the French survey made by Roy in 1787, by 1810, one inch to the mile maps of most of the south of England were completed, but were withdrawn from sale between 1811 and 1816 because of security fears. It was gruelling work, major Thomas Colby, later the longest serving director general of Ordnance Survey, in 1824, Colby and most of his staff moved to Ireland to work on a six-inches-to-the-mile valuation survey
2.
Surveying
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Surveying or land surveying is the technique, profession, and science of determining the terrestrial or three-dimensional position of points and the distances and angles between them. A land surveying professional is called a land surveyor, Surveyors work with elements of geometry, trigonometry, regression analysis, physics, engineering, metrology, programming languages and the law. Surveying has been an element in the development of the environment since the beginning of recorded history. The planning and execution of most forms of construction require it and it is also used in transport, communications, mapping, and the definition of legal boundaries for land ownership. It is an important tool for research in other scientific disciplines. Basic surveyance has occurred since humans built the first large structures, the prehistoric monument at Stonehenge was set out by prehistoric surveyors using peg and rope geometry. In ancient Egypt, a rope stretcher would use simple geometry to re-establish boundaries after the floods of the Nile River. The almost perfect squareness and north-south orientation of the Great Pyramid of Giza, built c.2700 BC, the Groma instrument originated in Mesopotamia. The mathematician Liu Hui described ways of measuring distant objects in his work Haidao Suanjing or The Sea Island Mathematical Manual, the Romans recognized land surveyors as a profession. They established the basic measurements under which the Roman Empire was divided, Roman surveyors were known as Gromatici. In medieval Europe, beating the bounds maintained the boundaries of a village or parish and this was the practice of gathering a group of residents and walking around the parish or village to establish a communal memory of the boundaries. Young boys were included to ensure the memory lasted as long as possible, in England, William the Conqueror commissioned the Domesday Book in 1086. It recorded the names of all the owners, the area of land they owned, the quality of the land. It did not include maps showing exact locations, abel Foullon described a plane table in 1551, but it is thought that the instrument was in use earlier as his description is of a developed instrument. Gunters chain was introduced in 1620 by English mathematician Edmund Gunter and it enabled plots of land to be accurately surveyed and plotted for legal and commercial purposes. Leonard Digges described a Theodolite that measured horizontal angles in his book A geometric practice named Pantometria, joshua Habermel created a theodolite with a compass and tripod in 1576. Johnathon Sission was the first to incorporate a telescope on a theodolite in 1725, in the 18th century, modern techniques and instruments for surveying began to be used. Jesse Ramsden introduced the first precision theodolite in 1787 and it was an instrument for measuring angles in the horizontal and vertical planes
3.
Level staff
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It cannot be used without a leveling instrument. Levelling rods can be one piece, but many are sectional and can be shortened for storage, there are many types of rods, with names that identify the form of the graduations and other characteristics. Markings can be in imperial or metric units, some rods are graduated on one side only while others are marked on both sides. If marked on both sides, the markings can be identical or can have imperial units on one side, in the photograph on the right, both a metric and imperial levelling rod are seen. This is an aluminum rod, coated white with markings in contrasting colours. The imperial side has a yellow background. The metric rod has major numbered graduations in meters and tenths of meters, between the major marks are either a pattern of squares and spaces in different colours or an E shape with horizontal components and spaces between of equal size. In both parts of the pattern, the squares, lines or spaces are precisely one centimetre high. When viewed through a telescope, the observer can easily visually interpolate a 1 cm mark to a quarter of its height. Usually readings are interpolated to mm, on this side of the rod, the colours of the markings alternate between red and black with each meter of length. The imperial graduations are in feet, tenths of a foot, the tenths of a foot point is indicated by the top of the long mark with the upward sloped end. The point halfway between tenths of a foot marks is indicated by the bottom of a medium length black mark with a sloped end. Each mark or space is approximately 3mm, yielding roughly the same accuracy as the metric rod, rods come in two classes, Self-reading rods. Self-reading rods are rods that are read by the person viewing the rod through the telescope of the instrument, the graduations are sufficiently clear to read with good accuracy. Target rods, on the hand, are equipped with a target. The target is a round or oval plate marked in quarters in contrasting colours such as red, a hole in the centre allows the instrument user to see the rods scale. The target is adjusted by the according to the instructions from the instrument man. When the target is set to align with the crosshairs of the instrument, the target may have a vernier to allow fractional increments of the graduation to be read
4.
Broad arrow
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A broad arrow is a type of arrow with a typically flat barbed head. It is a symbol used traditionally in heraldry, most notably in England, the broad arrow as a heraldic device has two tapering blades, known as barbs. When these barbs are engrailed on the inside, it is called a pheon, parkers A Glossary of Terms Used in Heraldry states, A broad arrow differs somewhat. And resembles a pheon, except in the omission of the edge on the inside of the barbs. The pheon, the broad arrow, occurs in heraldry in the arms of the Sidney and Coates families. The colleges newsletter for alumni is also called Pheon, the Pheon also appears in the arms of Hampden-Sydney College. The Office of Ordnance was created by Henry VIII in 1544 and it became the Board of Ordnance in 1597, its principal duties being to supply guns, ammunition, stores and equipment to the Kings Navy. The Office and Board used the arrow to signify at first objects purchased from the monarchs money. The introduction of this symbol is attributed to Sir Philip Sidney, Joint Master of the Ordnance in 1585/6, the broad arrow marks were also used by Commonwealth countries on their ordnance. With the demise of the Board in 1855, the War Department, similarly to hallmarks, it is currently a criminal offence in the United Kingdom to reproduce the broad arrow without authority. Section 4 of the Public Stores Act 1875 makes it illegal to use the arrow on any goods without permission. The broad arrow was used by the British to mark trees intended for ship building use in North America during colonial times, three axe strikes, resembling an arrowhead and shaft, were marked on large mast-grade trees. We. forbid all persons whatsoever from felling, cutting or destroying any such trees without the license from us. Initially England imported its mast trees from the Baltic states, but it was an expensive, lengthy, much of British naval policy at the time revolved around keeping the trade route to the Baltics open. With Baltic timber becoming less appealing to use, the Admiraltys eye turned towards the Colonies, colonists paid little attention to the Charters Mast Preservation Clause, and tree harvesting increased with disregard for broad arrow protected trees. However, as Baltic imports decreased, the British timber trade increasingly depended on North American trees and this process was open to abuse, and the British monopoly was very unpopular with colonists. Part of the reason was that many protected trees were on either town-owned or privately owned lands, colonists could only sell mast trees to the British, but were substantially underpaid for the lumber. Even though it was illegal for the colonists to sell to enemies of the crown, acts of Parliament in 1711,1722 and 1772 extended protection finally to 12-inch-diameter trees and resulted in the Pine Tree Riot that same year
5.
Height
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Height is the measure of vertical distance, either how tall something is, or how high up it is. For example The height of the building is 50 m or The height of the airplane is 10,000 m, when used to describe how high something like an airplane or mountain peak is from sea level, height is more often called altitude. Height is measured along the axis between a specified point and another. English high is derived from Old English hēah, ultimately from Proto-Germanic *xauxa-z, the derived noun height, also the obsolete forms heighth and highth, is from Old English híehþo, later héahþu, as it were from Proto-Germanic *xaux-iþa. In elementary models of space, height may indicate the third dimension, height is normal to the plane formed by the length and width. Height is also used as a name for more abstract definitions. Although height is relative to a plane of reference, most measurements of height in the world are based upon a zero surface. Both altitude and elevation, two synonyms for height, are defined as the position of a point above the mean sea level. One can extend the surface under the continents, naively. In practice, the sea level under a continent has to be computed from gravity measurements, instead of using the sea level, geodesists often prefer to define height from the surface of a reference ellipsoid, see Geodetic system, vertical datum. Defining the height of geographic landmarks becomes a question of reference, in aviation terminology, the terms height, altitude, and elevation are not synonyms. Usually, the altitude of an aircraft is measured from sea level, Elevation is also measured from sea level, but is most often regarded as a property of the ground. Thus, elevation plus height can equal altitude, but the term altitude has several meanings in aviation, Human height is one of the areas of study within anthropometry. While height variations within a population are largely genetic, height variations between populations are mostly environmental, the United Nations uses height to monitor changes in the nutrition of developing nations. In human populations, average height can distill down complex data about the birth, upbringing, social class, diet. Acrophobia Centimetre–gram–second system of units Chinese units of measurement Elevation Human height Imperial units International System of Units United States customary units
6.
Sea level
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Mean sea level is an average level of the surface of one or more of Earths oceans from which heights such as elevations may be measured. A common and relatively straightforward mean sea-level standard is the midpoint between a low and mean high tide at a particular location. Sea levels can be affected by factors and are known to have varied greatly over geological time scales. The careful measurement of variations in MSL can offer insights into ongoing climate change, the term above sea level generally refers to above mean sea level. Precise determination of a sea level is a difficult problem because of the many factors that affect sea level. Sea level varies quite a lot on several scales of time and this is because the sea is in constant motion, affected by the tides, wind, atmospheric pressure, local gravitational differences, temperature, salinity and so forth. The easiest way this may be calculated is by selecting a location and calculating the mean sea level at that point, for example, a period of 19 years of hourly level observations may be averaged and used to determine the mean sea level at some measurement point. One measures the values of MSL in respect to the land, hence a change in MSL can result from a real change in sea level, or from a change in the height of the land on which the tide gauge operates. In the UK, the Ordnance Datum is the sea level measured at Newlyn in Cornwall between 1915 and 1921. Prior to 1921, the datum was MSL at the Victoria Dock, in Hong Kong, mPD is a surveying term meaning metres above Principal Datum and refers to height of 1. 230m below the average sea level. In France, the Marégraphe in Marseilles measures continuously the sea level since 1883 and it is used for a part of continental Europe and main part of Africa as official sea level. Elsewhere in Europe vertical elevation references are made to the Amsterdam Peil elevation, satellite altimeters have been making precise measurements of sea level since the launch of TOPEX/Poseidon in 1992. A joint mission of NASA and CNES, TOPEX/Poseidon was followed by Jason-1 in 2001, height above mean sea level is the elevation or altitude of an object, relative to the average sea level datum. It is also used in aviation, where some heights are recorded and reported with respect to sea level, and in the atmospheric sciences. An alternative is to base height measurements on an ellipsoid of the entire Earth, in aviation, the ellipsoid known as World Geodetic System 84 is increasingly used to define heights, however, differences up to 100 metres exist between this ellipsoid height and mean tidal height. The alternative is to use a vertical datum such as NAVD88. When referring to geographic features such as mountains on a topographic map, the elevation of a mountain denotes the highest point or summit and is typically illustrated as a small circle on a topographic map with the AMSL height shown in metres, feet or both. In the rare case that a location is below sea level, for one such case, see Amsterdam Airport Schiphol
7.
Geoid
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The geoid is the shape that the surface of the oceans would take under the influence of Earths gravity and rotation alone, in the absence of other influences such as winds and tides. This surface is extended through the continents, all points on a geoid surface have the same gravity potential energy. The geoid can be defined at any value of gravitational potential such as within the earths crust or far out in space and it does not correspond to the actual surface of Earths crust, but to a surface which can only be known through extensive gravitational measurements and calculations. It is often described as the true figure of the Earth. The surface of the geoid is higher than the reference ellipsoid wherever there is a gravity anomaly. The geoid surface is irregular, unlike the ellipsoid which is a mathematical idealized representation of the physical Earth. Although the physical Earth has excursions of +8,848 m and −429 m, If the ocean surface were isopycnic and undisturbed by tides, currents, or weather, it would closely approximate the geoid. The permanent deviation between the geoid and mean sea level is called ocean surface topography, If the continental land masses were criss-crossed by a series of tunnels or canals, the sea level in these canals would also very nearly coincide with the geoid. This means that when traveling by ship, one does not notice the undulations of the geoid, the vertical is always perpendicular to the geoid. Likewise, spirit levels will always be parallel to the geoid, a long voyage, indicate height variations, even though the ship will always be at sea level. This is because GPS satellites, orbiting about the center of gravity of the Earth, to obtain ones geoidal height, a raw GPS reading must be corrected. Conversely, height determined by spirit leveling from a tidal measurement station, as in land surveying. Modern GPS receivers have a grid implemented inside where they obtain the height over the World Geodetic System ellipsoid from the current position. Then they are able to correct the height above WGS ellipsoid to the height above WGS84 geoid, in that case when the height is not zero on a ship it is due to various other factors such as ocean tides, atmospheric pressure and local sea surface topography. The gravitational field of the earth is neither perfect n If that perfect sphere were then covered in water, instead, the water level would be higher or lower depending on the particular strength of gravity in that location. Spherical harmonics are used to approximate the shape of the geoid. The current best such set of spherical harmonic coefficients is EGM96, the geoid is a particular equipotential surface, and is somewhat involved to compute. The gradient of this also provides a model of the gravitational acceleration
8.
Triangulation
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In trigonometry and geometry, triangulation is the process of determining the location of a point by forming triangles to it from known points. Optical 3D measuring systems use this principle as well in order to determine the spatial dimensions, basically, the configuration consists of two sensors observing the item. One of the sensors is typically a digital device. The projection centers of the sensors and the point on the object’s surface define a triangle. Within this triangle, the distance between the sensors is the base b and must be known, by determining the angles between the projection rays of the sensors and the basis, the intersection point, and thus the 3D coordinate, is calculated from the triangular relations. Triangulation today is used for many purposes, including surveying, navigation, metrology, astrometry, binocular vision, model rocketry, the use of triangles to estimate distances dates to antiquity. He measured the length of the shadows and that of his own at the same moment. Such techniques would have been familiar to the ancient Egyptians. Problem 57 of the Rhind papyrus, a thousand years earlier, defines the seqt or seked as the ratio of the run to the rise of a slope, i. e. the reciprocal of gradients as measured today. The slopes and angles were measured using a rod that the Greeks called a dioptra
9.
Triangulation station
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The station is usually set up by a government with known coordinate and elevation published. Many stations are located on hilltops for the purposes of visibility, a graven metal plate on the top of a pillar may provide a mounting point for a theodolite or reflector. Trigonometrical stations are grouped together to form a network of triangulation, positions of all land boundaries, roads, railways, bridges and other infrastructure can be accurately located by the network, a task that is essential to the construction of modern infrastructure. Apart from the known stations set up by government, some temporary trigonometrical stations are set up near construction sites for monitoring the precision, some trigonometrical stations use the Global Positioning System for convenience, however, the accuracy depends on factors such as ionospheric and tropospheric propagation delay errors. Although stations are no longer required for many surveying purposes, they remain useful to hikers as navigational aids and these trig stations are clearly visible for many kilometres and useful for hikers. In Japan, there are five classes of triangulation stations, Class 1 They are installed approximately every 40 kilometres, There are about 1000 throughout Japan. The pillars are 18 centimetres on a side, and each pillar is anchored with two large perpendicular rocks buried underground. Class 2 They are installed approximately every 8 kilometres, There are about 5000 throughout Japan, and the pillars are 15 centimetres on a side. Each pillar is anchored with a large perpendicular rock buried underground. Class 3 There are about 32,000 installed throughout Japan, the pillars are 15 centimetres on a side, and each pillar is anchored with a large perpendicular rock buried underground. Class 4 They are installed approximately every 2 kilometres, and there are about 69,000 throughout Japan, the pillars are 12 centimetres on a side, and each pillar is anchored with a large perpendicular rock buried underground. Class 5 These markers were installed in 1899 and are the predecessors to the modern triangulation stations used in Japan today and they are generally not used anymore since the installation of the Class 1-4 stations. Some of them still exist at various locations throughout Japan, in Spain there are 11,000 triangulation stations, concrete buildings which typically consist of a cylinder 120 cm high and 30 cm diameter over a concrete cubic base. They were erected by the Instituto Geográfico Nacional, usually painted in white, in the United Kingdom, trig points are typically concrete pillars, and were erected by the Ordnance Survey. The process of placing trig points on top of prominent hills, the Ordnance Surveys first trig point was erected on 18 April 1936 near Cold Ashby, Northamptonshire. In low-lying or flat areas some trig points are only a few metres above sea level, in most of the UK, trig points are truncated square concrete pyramids or obelisks tapering towards the top. On the top a brass plate with three arms and a depression is fixed, it is used to mount and centre a theodolite used to take angular measurements to neighbouring trig points. A benchmark is set on the side, marked with the letters O S B M
10.
Church (building)
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A church building, often simply called a church, is a building used for Christian religious activities, particularly worship services. The term in its sense is most often used by Christians to refer to their religious buildings. In traditional Christian architecture, the church is arranged in the shape of a Christian cross. When viewed from plan view the longest part of a cross is represented by the aisle, towers or domes are often added with the intention of directing the eye of the viewer towards the heavens and inspiring church visitors. The earliest identified Christian church was a church founded between 233 and 256. During the 11th through 14th centuries, a wave of building of cathedrals, a cathedral is a church, usually Roman Catholic, Anglican, Oriental Orthodox or Eastern Orthodox, housing the seat of a bishop. In standard Greek usage, the word ecclesia was retained to signify both a specific edifice of Christian worship, and the overall community of the faithful. This usage was retained in Latin and the languages derived from Latin, as well as in the Celtic languages. In the Germanic and some Slavic languages, the word kyriak-ós/-ē/-ón was adopted instead, in Old English the sequence of derivation started as cirice, then churche, and eventually church in its current pronunciation. German Kirche, Scottish kirk, Russian церковь, etc. are all similarly derived, according to the New Testament, the earliest Christians did not build church buildings. Instead, they gathered in homes or in Jewish worship places like the Second Temple or synagogues, the earliest archeologically identified Christian church is a house church, the Dura-Europos church, founded between 233 and 256. During the 11th through 14th centuries, a wave of building of cathedrals, in addition to being a place of worship, the cathedral or parish church was used by the community in other ways. It could serve as a place for guilds or a hall for banquets. Mystery plays were performed in cathedrals, and cathedrals might also be used for fairs. The church could be used as a place to thresh and store grain, a common architecture for churches is the shape of a cross. These churches also often have a dome or other large vaulted space in the interior to represent or draw attention to the heavens. Other common shapes for churches include a circle, to represent eternity, or an octagon or similar star shape, another common feature is the spire, a tall tower on the west end of the church or over the crossing. The Latin word basilica was used to describe a Roman public building
11.
Chimney
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A chimney is a structure that provides ventilation for hot flue gases or smoke from a boiler, stove, furnace or fireplace to the outside atmosphere. Chimneys are typically vertical, or as near as possible to vertical, to ensure that the gases flow smoothly, drawing air into the combustion in what is known as the stack, the space inside a chimney is called a flue. Chimneys may be found in buildings, steam locomotives and ships, in the United States, the term smokestack is also used when referring to locomotive chimneys or ship chimneys, and the term funnel can also be used. The height of a chimney influences its ability to transfer flue gases to the environment via stack effect. Additionally, the dispersion of pollutants at higher altitudes can reduce their impact on the immediate surroundings, in the case of chemically aggressive output, a sufficiently tall chimney can allow for partial or complete self-neutralization of airborne chemicals before they reach ground level. The dispersion of pollutants over an area can reduce their concentrations. Romans used tubes inside the walls to draw out of bakeries. The earliest extant example of an English chimney is at the keep of Conisbrough Castle in Yorkshire, however, they did not become common in houses until the 16th and 17th centuries. Smoke hoods were a method of collecting the smoke into a chimney. Another step in the development of chimneys was the use of built in ovens which allowed the household to bake at home, industrial chimneys became common in the late 18th century. Chimneys in ordinary dwellings were first built of wood and plaster or mud, since then chimneys have traditionally been built of brick or stone, both in small and large buildings. Early chimneys were of a brick construction. Later chimneys were constructed by placing the bricks around tile liners, to control downdrafts, venting caps with a variety of designs are sometimes placed on the top of chimneys. In the 18th and 19th centuries, the used to extract lead from its ore produced large amounts of toxic fumes. Lead and silver deposits formed on the inside of these long chimneys, todays central heating systems have made chimney placement less critical, and the use of non-structural gas vent pipe allows a flue gas conduit to be installed around obstructions and through walls. In fact, most modern high-efficiency heating appliances do not require a chimney, such appliances are generally installed near an external wall, and a noncombustible wall thimble allows a vent pipe to run directly through the external wall. On a pitched roof where a chimney penetrates a roof, flashing is used to seal up the joints, the down-slope piece is called an apron, the sides receive step flashing and a cricket is used to divert water around the upper side of the chimney underneath the flashing. Industrial chimneys are commonly referred to as flue gas stacks and are generally external structures and they are generally located adjacent to a steam-generating boiler or industrial furnace and the gases are carried to them with ductwork
12.
United Kingdom
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The United Kingdom of Great Britain and Northern Ireland, commonly known as the United Kingdom or Britain, is a sovereign country in western Europe. Lying off the north-western coast of the European mainland, the United Kingdom includes the island of Great Britain, Northern Ireland is the only part of the United Kingdom that shares a land border with another sovereign state—the Republic of Ireland. The Irish Sea lies between Great Britain and Ireland, with an area of 242,500 square kilometres, the United Kingdom is the 78th-largest sovereign state in the world and the 11th-largest in Europe. It is also the 21st-most populous country, with an estimated 65.1 million inhabitants, together, this makes it the fourth-most densely populated country in the European Union. The United Kingdom is a monarchy with a parliamentary system of governance. The monarch is Queen Elizabeth II, who has reigned since 6 February 1952, other major urban areas in the United Kingdom include the regions of Birmingham, Leeds, Glasgow, Liverpool and Manchester. The United Kingdom consists of four countries—England, Scotland, Wales, the last three have devolved administrations, each with varying powers, based in their capitals, Edinburgh, Cardiff and Belfast, respectively. The relationships among the countries of the UK have changed over time, Wales was annexed by the Kingdom of England under the Laws in Wales Acts 1535 and 1542. A treaty between England and Scotland resulted in 1707 in a unified Kingdom of Great Britain, which merged in 1801 with the Kingdom of Ireland to form the United Kingdom of Great Britain and Ireland. Five-sixths of Ireland seceded from the UK in 1922, leaving the present formulation of the United Kingdom of Great Britain, there are fourteen British Overseas Territories. These are the remnants of the British Empire which, at its height in the 1920s, British influence can be observed in the language, culture and legal systems of many of its former colonies. The United Kingdom is a country and has the worlds fifth-largest economy by nominal GDP. The UK is considered to have an economy and is categorised as very high in the Human Development Index. It was the worlds first industrialised country and the worlds foremost power during the 19th, the UK remains a great power with considerable economic, cultural, military, scientific and political influence internationally. It is a nuclear weapons state and its military expenditure ranks fourth or fifth in the world. The UK has been a permanent member of the United Nations Security Council since its first session in 1946 and it has been a leading member state of the EU and its predecessor, the European Economic Community, since 1973. However, on 23 June 2016, a referendum on the UKs membership of the EU resulted in a decision to leave. The Acts of Union 1800 united the Kingdom of Great Britain, Scotland, Wales and Northern Ireland have devolved self-government
13.
Canada
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Canada is a country in the northern half of North America. Canadas border with the United States is the worlds longest binational land border, the majority of the country has a cold or severely cold winter climate, but southerly areas are warm in summer. Canada is sparsely populated, the majority of its territory being dominated by forest and tundra. It is highly urbanized with 82 per cent of the 35.15 million people concentrated in large and medium-sized cities, One third of the population lives in the three largest cities, Toronto, Montreal and Vancouver. Its capital is Ottawa, and other urban areas include Calgary, Edmonton, Quebec City, Winnipeg. Various aboriginal peoples had inhabited what is now Canada for thousands of years prior to European colonization. Pursuant to the British North America Act, on July 1,1867, the colonies of Canada, New Brunswick and this began an accretion of provinces and territories to the mostly self-governing Dominion to the present ten provinces and three territories forming modern Canada. With the Constitution Act 1982, Canada took over authority, removing the last remaining ties of legal dependence on the Parliament of the United Kingdom. Canada is a parliamentary democracy and a constitutional monarchy, with Queen Elizabeth II being the head of state. The country is officially bilingual at the federal level and it is one of the worlds most ethnically diverse and multicultural nations, the product of large-scale immigration from many other countries. Its advanced economy is the eleventh largest in the world, relying chiefly upon its abundant natural resources, Canadas long and complex relationship with the United States has had a significant impact on its economy and culture. Canada is a country and has the tenth highest nominal per capita income globally as well as the ninth highest ranking in the Human Development Index. It ranks among the highest in international measurements of government transparency, civil liberties, quality of life, economic freedom, Canada is an influential nation in the world, primarily due to its inclusive values, years of prosperity and stability, stable economy, and efficient military. While a variety of theories have been postulated for the origins of Canada. In 1535, indigenous inhabitants of the present-day Quebec City region used the word to direct French explorer Jacques Cartier to the village of Stadacona, from the 16th to the early 18th century Canada referred to the part of New France that lay along the St. Lawrence River. In 1791, the area became two British colonies called Upper Canada and Lower Canada collectively named The Canadas, until their union as the British Province of Canada in 1841. Upon Confederation in 1867, Canada was adopted as the name for the new country at the London Conference. The transition away from the use of Dominion was formally reflected in 1982 with the passage of the Canada Act, later that year, the name of national holiday was changed from Dominion Day to Canada Day
14.
Natural Resources Canada
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It was created in 1995 by amalgamating the now-defunct Departments of Energy, Mines and Resources and Forestry. Natural Resources Canada works to ensure the development of Canadas natural resources, including energy, forests. NRCan also uses its expertise in earth sciences to build and maintain a knowledge base of our landmass. To promote internal collaboration, NRCan has implemented a departmental wide wiki based on MediaWiki, under the Canadian constitution, responsibility for natural resources belongs to the provinces, not the federal government. However, the government has jurisdiction over off-shore resources, trade and commerce in natural resources, statistics, international relations. The current Minister of Natural Resources is Jim Carr as of November 4,2015, the department is governed by the Resources and Technical Surveys Act, R. S. C. C. R-7 and the Department of Natural Resources Act, S. C, structured along business lines according to types of natural resources and areas of interest
15.
France
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France, officially the French Republic, is a country with territory in western Europe and several overseas regions and territories. The European, or metropolitan, area of France extends from the Mediterranean Sea to the English Channel and the North Sea, Overseas France include French Guiana on the South American continent and several island territories in the Atlantic, Pacific and Indian oceans. France spans 643,801 square kilometres and had a population of almost 67 million people as of January 2017. It is a unitary republic with the capital in Paris. Other major urban centres include Marseille, Lyon, Lille, Nice, Toulouse, during the Iron Age, what is now metropolitan France was inhabited by the Gauls, a Celtic people. The area was annexed in 51 BC by Rome, which held Gaul until 486, France emerged as a major European power in the Late Middle Ages, with its victory in the Hundred Years War strengthening state-building and political centralisation. During the Renaissance, French culture flourished and a colonial empire was established. The 16th century was dominated by civil wars between Catholics and Protestants. France became Europes dominant cultural, political, and military power under Louis XIV, in the 19th century Napoleon took power and established the First French Empire, whose subsequent Napoleonic Wars shaped the course of continental Europe. Following the collapse of the Empire, France endured a succession of governments culminating with the establishment of the French Third Republic in 1870. Following liberation in 1944, a Fourth Republic was established and later dissolved in the course of the Algerian War, the Fifth Republic, led by Charles de Gaulle, was formed in 1958 and remains to this day. Algeria and nearly all the colonies became independent in the 1960s with minimal controversy and typically retained close economic. France has long been a centre of art, science. It hosts Europes fourth-largest number of cultural UNESCO World Heritage Sites and receives around 83 million foreign tourists annually, France is a developed country with the worlds sixth-largest economy by nominal GDP and ninth-largest by purchasing power parity. In terms of household wealth, it ranks fourth in the world. France performs well in international rankings of education, health care, life expectancy, France remains a great power in the world, 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 member state of the European Union and the Eurozone. It is also a member of the Group of 7, North Atlantic Treaty Organization, Organisation for Economic Co-operation and Development, the World Trade Organization, originally applied to the whole Frankish Empire, the name France comes from the Latin Francia, or country of the Franks
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India
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India, officially the Republic of India, is a country in South Asia. It is the seventh-largest country by area, the second-most populous country, and it is bounded by the Indian Ocean on the south, the Arabian Sea on the southwest, and the Bay of Bengal on the southeast. It shares land borders with Pakistan to the west, China, Nepal, and Bhutan to the northeast, in the Indian Ocean, India is in the vicinity of Sri Lanka and the Maldives. Indias Andaman and Nicobar Islands share a border with Thailand. The Indian subcontinent was home to the urban Indus Valley Civilisation of the 3rd millennium BCE, in the following millennium, the oldest scriptures associated with Hinduism began to be composed. Social stratification, based on caste, emerged in the first millennium BCE, early political consolidations took place under the Maurya and Gupta empires, the later peninsular Middle Kingdoms influenced cultures as far as southeast Asia. In the medieval era, Judaism, Zoroastrianism, Christianity, and Islam arrived, much of the north fell to the Delhi sultanate, the south was united under the Vijayanagara Empire. The economy expanded in the 17th century in the Mughal empire, in the mid-18th century, the subcontinent came under British East India Company rule, and in the mid-19th under British crown rule. A nationalist movement emerged in the late 19th century, which later, under Mahatma Gandhi, was noted for nonviolent resistance, in 2015, the Indian economy was the worlds seventh largest by nominal GDP and third largest by purchasing power parity. Following market-based economic reforms in 1991, India became one of the major economies and is considered a newly industrialised country. However, it continues to face the challenges of poverty, corruption, malnutrition, a nuclear weapons state and regional power, it has the third largest standing army in the world and ranks sixth in military expenditure among nations. India is a constitutional republic governed under a parliamentary system. It is a pluralistic, multilingual and multi-ethnic society and is home to a diversity of wildlife in a variety of protected habitats. The name India is derived from Indus, which originates from the Old Persian word Hindu, the latter term stems from the Sanskrit word Sindhu, which was the historical local appellation for the Indus River. The ancient Greeks referred to the Indians as Indoi, which translates as The people of the Indus, the geographical term Bharat, which is recognised by the Constitution of India as an official name for the country, is used by many Indian languages in its variations. Scholars believe it to be named after the Vedic tribe of Bharatas in the second millennium B. C. E and it is also traditionally associated with the rule of the legendary emperor Bharata. Gaṇarājya is the Sanskrit/Hindi term for republic dating back to the ancient times, hindustan is a Persian name for India dating back to the 3rd century B. C. E. It was introduced into India by the Mughals and widely used since then and its meaning varied, referring to a region that encompassed northern India and Pakistan or India in its entirety
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Survey of India
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The Survey of India is Indias central engineering agency in charge of mapping and surveying. Set up in 1767 to help consolidate the territories of the British East India Company, the Survey of Indias distinguished history includes the handling of the mammoth Great Trigonometrical Survey under William Lambton and George Everest and the discovery of Mt. Everest. Its members are from Survey of India Service cadre of Civil Services of India and it is headed by the Surveyor General of India. Survey of India publishes maps and the unrestricted category maps can be obtained at very reasonable prices from its several Geo-spatial data centers, restricted category maps require due approval from government authorities. Many other rules govern the sale and use of Survey of India maps, only an Indian citizen may purchase topographic maps and these may not be exported from India for any reason. The history of the Survey of India dates back to the 18th Century, a) First Survey in India Baramahal, the present Dharmapuri, Krishnagiri and North Arcot were called as baramahal. In Letter Dated 04.10.1797 the British Government appreciated Col. Alexander Read, b) The Great Trigonometry Survey The Great Trigonometry Survey was started by British surveyor Col. William Lambton on the 10th of April 1802. It was started from St. Thomas Mount, Chennai to foothills of Himalayas and it took 57 days to measure the 12-km base line. 36 inch huge ½ ton weight Theodolite was used to measure and this 5-decade project was completed under Survey General Lt George Everest in the year 1852. Surveyor Radhanath Sikdar measured Mount Everest in 1852, with a height of 29,002 feet, modern measurements indicate the height is 29,037 feet. This is regarded as the beginning of systematic topographical mapping in India, the Survey of India, headquartered at Dehra Dun, has 18 civil engineering divisions ranging from the prediction of tides to aerial survey. It has 23 Geo-spatial Data Centers spread across India, each catering to the administrative area. Surveyors are the back bone of Survey of India. The Survey of India acts as adviser to the Government of India on all matters, viz Geodesy, Photogrammetry, Mapping. However, the duties and responsibilities of the Survey of India are enumerated below, All Geodetic Control and Geodetic. All Topographical Control, Surveys and Mapping within India, Mapping and Production of Geographical Maps and Aeronautical Charts. Survey of Forests, Cantonments, large scale city surveys, guide maps, Survey and Mapping of special maps. Demarcation of the External Boundaries of the Republic of India, their depiction on maps published in the country, training of officers and staff required for the Department, trainees from Central Government Departments and States and trainees from Foreign Countries as are sponsored by the *Government of India. Research and Development in Cartography, Printing, Geodesy, Photogrammetry, Topographical Surveys, prediction of tides at 44 ports including 14 foreign ports and publication of Tide Tables one year in advance to support navigational activities
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Italy
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Italy, officially the Italian Republic, is a unitary parliamentary republic in Europe. Located in the heart of the Mediterranean Sea, Italy shares open land borders with France, Switzerland, Austria, Slovenia, San Marino, Italy covers an area of 301,338 km2 and has a largely temperate seasonal climate and Mediterranean climate. Due to its shape, it is referred to in Italy as lo Stivale. With 61 million inhabitants, it is the fourth most populous EU member state, the Italic tribe known as the Latins formed the Roman Kingdom, which eventually became a republic that conquered and assimilated other nearby civilisations. The legacy of the Roman Empire is widespread and can be observed in the distribution of civilian law, republican governments, Christianity. The Renaissance began in Italy and spread to the rest of Europe, bringing a renewed interest in humanism, science, exploration, Italian culture flourished at this time, producing famous scholars, artists and polymaths such as Leonardo da Vinci, Galileo, Michelangelo and Machiavelli. The weakened sovereigns soon fell victim to conquest by European powers such as France, Spain and Austria. Despite being one of the victors in World War I, Italy entered a period of economic crisis and social turmoil. The subsequent participation in World War II on the Axis side ended in defeat, economic destruction. Today, Italy has the third largest economy in the Eurozone and it has a very high level of human development and is ranked sixth in the world for life expectancy. The country plays a prominent role in regional and global economic, military, cultural and diplomatic affairs, as a reflection of its cultural wealth, Italy is home to 51 World Heritage Sites, the most in the world, and is the fifth most visited country. The assumptions on the etymology of the name Italia are very numerous, according to one of the more common explanations, the term Italia, from Latin, Italia, was borrowed through Greek from the Oscan Víteliú, meaning land of young cattle. The bull was a symbol of the southern Italic tribes and was often depicted goring the Roman wolf as a defiant symbol of free Italy during the Social War. Greek historian Dionysius of Halicarnassus states this account together with the legend that Italy was named after Italus, mentioned also by Aristotle and Thucydides. The name Italia originally applied only to a part of what is now Southern Italy – according to Antiochus of Syracuse, but by his time Oenotria and Italy had become synonymous, and the name also applied to most of Lucania as well. The Greeks gradually came to apply the name Italia to a larger region, excavations throughout Italy revealed a Neanderthal presence dating back to the Palaeolithic period, some 200,000 years ago, modern Humans arrived about 40,000 years ago. Other ancient Italian peoples of undetermined language families but of possible origins include the Rhaetian people and Cammuni. Also the Phoenicians established colonies on the coasts of Sardinia and Sicily, the Roman legacy has deeply influenced the Western civilisation, shaping most of the modern world
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Istituto Geografico Militare
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The Istituto Geografico Militare, or Military Geographic Institute is an Italian public organization, dependent on the Italian Army general staff. It is the mapping agency for Italy. Its headquarters are in via Cesare Battisti, Florence, and they occupy most part of Santissima Annunziata cloister and it was established by king Vittorio Emanuele II in 1861 and it is ruled by the law n.68 February 2,1960
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Japan
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Japan is a sovereign island nation in Eastern Asia. Located in the Pacific Ocean, it lies off the eastern coast of the Asia Mainland and stretches from the Sea of Okhotsk in the north to the East China Sea, the kanji that make up Japans name mean sun origin. 日 can be read as ni and means sun while 本 can be read as hon, or pon, Japan is often referred to by the famous epithet Land of the Rising Sun in reference to its Japanese name. Japan is an archipelago consisting of about 6,852 islands. The four largest are Honshu, Hokkaido, Kyushu and Shikoku, the country is divided into 47 prefectures in eight regions. Hokkaido being the northernmost prefecture and Okinawa being the southernmost one, the population of 127 million is the worlds tenth largest. Japanese people make up 98. 5% of Japans total population, approximately 9.1 million people live in the city of Tokyo, the capital of Japan. Archaeological research indicates that Japan was inhabited as early as the Upper Paleolithic period, the first written mention of Japan is in Chinese history texts from the 1st century AD. Influence from other regions, mainly China, followed by periods of isolation, from the 12th century until 1868, Japan was ruled by successive feudal military shoguns who ruled in the name of the Emperor. Japan entered into a period of isolation in the early 17th century. The Second Sino-Japanese War of 1937 expanded into part of World War II in 1941, which came to an end in 1945 following the bombings of Hiroshima and Nagasaki. Japan is a member of the UN, the OECD, the G7, the G8, the country has the worlds third-largest economy by nominal GDP and the worlds fourth-largest economy by purchasing power parity. It is also the worlds fourth-largest exporter and fourth-largest importer, although Japan has officially renounced its right to declare war, it maintains a modern military with the worlds eighth-largest military budget, used for self-defense and peacekeeping roles. Japan is a country with a very high standard of living. Its population enjoys the highest life expectancy and the third lowest infant mortality rate in the world, in ancient China, Japan was called Wo 倭. It was mentioned in the third century Chinese historical text Records of the Three Kingdoms in the section for the Wei kingdom, Wa became disliked because it has the connotation of the character 矮, meaning dwarf. The 倭 kanji has been replaced with the homophone Wa, meaning harmony, the Japanese word for Japan is 日本, which is pronounced Nippon or Nihon and literally means the origin of the sun. The earliest record of the name Nihon appears in the Chinese historical records of the Tang dynasty, at the start of the seventh century, a delegation from Japan introduced their country as Nihon
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Geospatial Information Authority of Japan
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The Geospatial Information Authority of Japan, or GSI, is the national institution responsible for surveying and mapping the national land of Japan. The former name of the organization from 1949 until March 2010 was Geographical Survey Institute and it is an organization attached to the Ministry of Land, Infrastructure, Transport and Tourism. Its main offices are situated in Tsukuba City of Ibaraki Prefecture and it also runs a museum, situated in Tsukuba, the Science Museum of Map and Survey. Stationary MT monitoring systems have been installed in Japan since April 1996, providing a continuous recording of MT signals at the Mizusawa Geodetic Observatory and these stations measure fluctuations in the earths electromagnetic field that correspond with seismic activity. The GSI featured in the novel Norwegian Wood by Haruki Murakami as the workplace of his roommate. At the time the novel was set, in the late sixties, japanese maps, the history of mapping in Japan. Japanese map symbols, the symbols used by the GSI in maps
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New Zealand
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New Zealand /njuːˈziːlənd/ is an island nation in the southwestern Pacific Ocean. The country geographically comprises two main landmasses—the North Island, or Te Ika-a-Māui, and the South Island, or Te Waipounamu—and around 600 smaller islands. New Zealand is situated some 1,500 kilometres east of Australia across the Tasman Sea and roughly 1,000 kilometres south of the Pacific island areas of New Caledonia, Fiji, because of its remoteness, it was one of the last lands to be settled by humans. During its long period of isolation, New Zealand developed a distinct biodiversity of animal, fungal, the countrys varied topography and its sharp mountain peaks, such as the Southern Alps, owe much to the tectonic uplift of land and volcanic eruptions. New Zealands capital city is Wellington, while its most populous city is Auckland, sometime between 1250 and 1300 CE, Polynesians settled in the islands that later were named New Zealand and developed a distinctive Māori culture. In 1642, Dutch explorer Abel Tasman became the first European to sight New Zealand, in 1840, representatives of Britain and Māori chiefs signed the Treaty of Waitangi, which declared British sovereignty over the islands. In 1841, New Zealand became a colony within the British Empire, today, the majority of New Zealands population of 4.7 million is of European descent, the indigenous Māori are the largest minority, followed by Asians and Pacific Islanders. Reflecting this, New Zealands culture is derived from Māori and early British settlers. The official languages are English, Māori and New Zealand Sign Language, New Zealand is a developed country and ranks highly in international comparisons of national performance, such as health, education, economic freedom and quality of life. Since the 1980s, New Zealand has transformed from an agrarian, Queen Elizabeth II is the countrys head of state and is represented by a governor-general. In addition, New Zealand is organised into 11 regional councils and 67 territorial authorities for local government purposes, the Realm of New Zealand also includes Tokelau, the Cook Islands and Niue, and the Ross Dependency, which is New Zealands territorial claim in Antarctica. New Zealand is a member of the United Nations, Commonwealth of Nations, ANZUS, Organisation for Economic Co-operation and Development, Pacific Islands Forum, and Asia-Pacific Economic Cooperation. Dutch explorer Abel Tasman sighted New Zealand in 1642 and called it Staten Landt, in 1645, Dutch cartographers renamed the land Nova Zeelandia after the Dutch province of Zeeland. British explorer James Cook subsequently anglicised the name to New Zealand, Aotearoa is the current Māori name for New Zealand. It is unknown whether Māori had a name for the country before the arrival of Europeans. Māori had several names for the two main islands, including Te Ika-a-Māui for the North Island and Te Waipounamu or Te Waka o Aoraki for the South Island. Early European maps labelled the islands North, Middle and South, in 1830, maps began to use North and South to distinguish the two largest islands and by 1907, this was the accepted norm. The New Zealand Geographic Board discovered in 2009 that the names of the North Island and South Island had never been formalised and this set the names as North Island or Te Ika-a-Māui, and South Island or Te Waipounamu
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Pakistan
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Pakistan, officially the Islamic Republic of Pakistan, is a federal parliamentary republic in South Asia on the crossroads of Central Asia and Western Asia. It is the sixth-most populous country with a population exceeding 200 million people, in terms of area, it is the 33rd-largest country in the world with an area covering 881,913 square kilometres. It is separated from Tajikistan by Afghanistans narrow Wakhan Corridor in the north, Pakistan is unique among Muslim countries in that it is the only country to have been created in the name of Islam. As a result of the Pakistan Movement led by Muhammad Ali Jinnah and it is an ethnically and linguistically diverse country, with a similarly diverse geography and wildlife. Initially a dominion, Pakistan adopted a constitution in 1956, becoming an Islamic republic, an ethnic civil war in 1971 resulted in the secession of East Pakistan as the new country of Bangladesh. The new constitution stipulated that all laws were to conform to the injunctions of Islam as laid down in the Quran. Pakistan has an economy with a well-integrated agriculture sector. The Pakistani economy is the 24th-largest in the world in terms of purchasing power and it is ranked among the emerging and growth-leading economies of the world, and is backed by one of the worlds largest and fastest-growing middle classes. The post-independence history of Pakistan has been characterised by periods of military rule, the country continues to face challenging problems such as illiteracy, healthcare, and corruption, but has substantially reduced poverty and terrorism and expanded per capita income. It is also a member of CERN. Pakistan is a signatory to the Kyoto Protocol, the Paris Agreement, the name Pakistan literally means land of the pure in Urdu and Persian. It is a play on the word pāk meaning pure in Persian and Pashto, the letter i was incorporated to ease pronunciation and form the linguistically correct and meaningful name. Some of the earliest ancient human civilisations in South Asia originated from areas encompassing present-day Pakistan, the earliest known inhabitants in the region were Soanian during the Lower Paleolithic, of whom stone tools have been found in the Soan Valley of Punjab. The Vedic Civilization, characterised by Indo-Aryan culture, laid the foundations of Hinduism, Multan was an important Hindu pilgrimage centre. The Vedic civilisation flourished in the ancient Gandhāran city of Takṣaśilā, the Indo-Greek Kingdom founded by Demetrius of Bactria included Gandhara and Punjab and reached its greatest extent under Menander, prospering the Greco-Buddhist culture in the region. Taxila had one of the earliest universities and centres of education in the world. At its zenith, the Rai Dynasty of Sindh ruled this region, the Pala Dynasty was the last Buddhist empire, which, under Dharampala and Devapala, stretched across South Asia from what is now Bangladesh through Northern India to Pakistan. The Arab conqueror Muhammad bin Qasim conquered the Indus valley from Sindh to Multan in southern Punjab in 711 AD, the Pakistan governments official chronology identifies this as the time when the foundation of Pakistan was laid
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South Africa
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South Africa, officially the Republic of South Africa, is the southernmost country in Africa. South Africa is the 25th-largest country in the world by land area and it is the southernmost country on the mainland of the Old World or the Eastern Hemisphere. About 80 percent of South Africans are of Sub-Saharan African ancestry, divided among a variety of ethnic groups speaking different Bantu languages, the remaining population consists of Africas largest communities of European, Asian, and multiracial ancestry. South Africa is a multiethnic society encompassing a variety of cultures, languages. Its pluralistic makeup is reflected in the recognition of 11 official languages. The country is one of the few in Africa never to have had a coup détat, however, the vast majority of black South Africans were not enfranchised until 1994. During the 20th century, the black majority sought to recover its rights from the dominant white minority, with this struggle playing a role in the countrys recent history. The National Party imposed apartheid in 1948, institutionalising previous racial segregation, since 1994, all ethnic and linguistic groups have held political representation in the countrys democracy, which comprises a parliamentary republic and nine provinces. South Africa is often referred to as the Rainbow Nation to describe the multicultural diversity. The World Bank classifies South Africa as an economy. Its economy is the second-largest in Africa, and the 34th-largest in the world, in terms of purchasing power parity, South Africa has the seventh-highest per capita income in Africa. However, poverty and inequality remain widespread, with about a quarter of the population unemployed, nevertheless, South Africa has been identified as a middle power in international affairs, and maintains significant regional influence. The name South Africa is derived from the geographic location at the southern tip of Africa. Upon formation the country was named the Union of South Africa in English, since 1961 the long form name in English has been the Republic of South Africa. In Dutch the country was named Republiek van Zuid-Afrika, replaced in 1983 by the Afrikaans Republiek van Suid-Afrika, since 1994 the Republic has had an official name in each of its 11 official languages. Mzansi, derived from the Xhosa noun umzantsi meaning south, is a name for South Africa. South Africa contains some of the oldest archaeological and human fossil sites in the world, extensive fossil remains have been recovered from a series of caves in Gauteng Province. The area is a UNESCO World Heritage site and has termed the Cradle of Humankind
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Spain
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By population, Spain is the sixth largest in Europe and the fifth in the European Union. Spains capital and largest city is Madrid, other urban areas include Barcelona, Valencia, Seville, Bilbao. Modern humans first arrived in the Iberian Peninsula around 35,000 years ago, in the Middle Ages, the area was conquered by Germanic tribes and later by the Moors. Spain is a democracy organised in the form of a government under a constitutional monarchy. It is a power and a major developed country with the worlds fourteenth largest economy by nominal GDP. Jesús Luis Cunchillos argues that the root of the span is the Phoenician word spy. Therefore, i-spn-ya would mean the land where metals are forged, two 15th-century Spanish Jewish scholars, Don Isaac Abravanel and Solomon ibn Verga, gave an explanation now considered folkloric. Both men wrote in two different published works that the first Jews to reach Spain were brought by ship by Phiros who was confederate with the king of Babylon when he laid siege to Jerusalem. This man was a Grecian by birth, but who had given a kingdom in Spain. He became related by marriage to Espan, the nephew of king Heracles, Heracles later renounced his throne in preference for his native Greece, leaving his kingdom to his nephew, Espan, from whom the country of España took its name. Based upon their testimonies, this eponym would have already been in use in Spain by c.350 BCE, Iberia enters written records as a land populated largely by the Iberians, Basques and Celts. Early on its coastal areas were settled by Phoenicians who founded Western Europe´s most ancient cities Cadiz, Phoenician influence expanded as much of the Peninsula was eventually incorporated into the Carthaginian Empire, becoming a major theater of the Punic Wars against the expanding Roman Empire. After an arduous conquest, the peninsula came fully under Roman Rule, during the early Middle Ages it came under Germanic rule but later, much of it was conquered by Moorish invaders from North Africa. In a process took centuries, the small Christian kingdoms in the north gradually regained control of the peninsula. The last Moorish kingdom fell in the same year Columbus reached the Americas, a global empire began which saw Spain become the strongest kingdom in Europe, the leading world power for a century and a half, and the largest overseas empire for three centuries. Continued wars and other problems led to a diminished status. The Napoleonic invasions of Spain led to chaos, triggering independence movements that tore apart most of the empire, eventually democracy was peacefully restored in the form of a parliamentary constitutional monarchy. Spain joined the European Union, experiencing a renaissance and steady economic growth
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United States
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Forty-eight of the fifty states and the federal district are contiguous and located in North America between Canada and Mexico. The state of Alaska is in the northwest corner of North America, bordered by Canada to the east, the state of Hawaii is an archipelago in the mid-Pacific Ocean. The U. S. territories are scattered about the Pacific Ocean, the geography, climate and wildlife of the country are extremely diverse. At 3.8 million square miles and with over 324 million people, the United States is the worlds third- or fourth-largest country by area, third-largest by land area. It is one of the worlds most ethnically diverse and multicultural nations, paleo-Indians migrated from Asia to the North American mainland at least 15,000 years ago. European colonization began in the 16th century, the United States emerged from 13 British colonies along the East Coast. Numerous disputes between Great Britain and the following the Seven Years War led to the American Revolution. On July 4,1776, during the course of the American Revolutionary War, the war ended in 1783 with recognition of the independence of the United States by Great Britain, representing the first successful war of independence against a European power. The current constitution was adopted in 1788, after the Articles of Confederation, the first ten amendments, collectively named the Bill of Rights, were ratified in 1791 and designed to guarantee many fundamental civil liberties. During the second half of the 19th century, the American Civil War led to the end of slavery in the country. By the end of century, the United States extended into the Pacific Ocean. The Spanish–American War and World War I confirmed the status as a global military power. The end of the Cold War and the dissolution of the Soviet Union in 1991 left the United States as the sole superpower. The U. S. is a member of the United Nations, World Bank, International Monetary Fund, Organization of American States. The United States is a developed country, with the worlds largest economy by nominal GDP. It ranks highly in several measures of performance, including average wage, human development, per capita GDP. While the U. S. economy is considered post-industrial, characterized by the dominance of services and knowledge economy, the United States is a prominent political and cultural force internationally, and a leader in scientific research and technological innovations. In 1507, the German cartographer Martin Waldseemüller produced a map on which he named the lands of the Western Hemisphere America after the Italian explorer and cartographer Amerigo Vespucci
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U.S. National Geodetic Survey
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United States Coast Survey and United States Coast and Geodetic Survey redirect here. Since its foundation in its present form in 1970, it has been part of the National Oceanic and Atmospheric Administration, the National Geodetic Surveys history and heritage are intertwined with those of other NOAA offices. As the U. S. Coast Survey and U. S, upon the creation of the Environmental Science Services Administration in 1965, the commissioned corps was separated from the Survey to become the Environmental Science Services Administration Corps. Thus, the National Geodetic Surveys ancestor organizations are also the ancestors of todays NOAA Corps, in addition, todays National Institute of Standards and Technology, although long since separated from the Survey, got its start as the Surveys Office of Weights and Measures. The National Geodetic Survey is an office of NOAAs National Ocean Service, NGS is responsible for defining the NSRS and its relationship with the International Terrestrial Reference Frame. The NSRS enables precise and accessible knowledge of things are in the United States. The NSRS may be divided into its geometric and physical components, the official geodetic datum of the United States, NAD83 defines the geometric relationship between points within the United States in three-dimensional space. The datum may be accessed via NGSs network of marks or through the Continuously Operating Reference Station network of GPS reference antennas. NGS is responsible for computing the relationship between NAD83 and the ITRF, the physical components of the NSRS are reflected in its height system, defined by the vertical datum NAVD88. This datum is a network of orthometric heights obtained through spirit leveling, NGS will release new datums in 2022. The North American Terrestrial Reference Frame of 2022 will supersede NAD83 in defining the relationship between the North American plate and the ITRF. United States territories on the Pacific, Caribbean, and Mariana plates will have their own respective geodetic datums, the North American-Pacific Geopotential Datum of 2022 will separately define the height system of the United States and its territories, replacing NAVD88. It will use a geoid model accurate to 1 centimeter to relate orthometric height to ellipsoidal height measured by GPS, NGS provides a number of other public services. The Online Positioning and User Service processes user-input GPS data and outputs position solutions within the NSRS, the agency offers other tools for conversion between datums. A Swiss immigrant with expertise in surveying and the standardization of weights and measures, Ferdinand R. Hassler, was selected to lead the Survey. Hassler departed on August 29,1811, but eight months later, while he was in England, Hassler did not return to the United States until August 16,1815. The Survey finally began surveying operations in 1816, when Hassler started work in the vicinity of New York City, the first baseline was measured and verified in 1817. S. S. Army and U. S. Navy responsibility for coastal surveys, Hassler was reappointed as the Surveys superintendent that year
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United States Army Corps of Engineers
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The United States Army Corps of Engineers, also sometimes shortened to CoE is a U. S. Although generally associated with dams, canals and flood protection in the United States, the Corps of Engineers provides outdoor recreation opportunities to the public, and provides 24% of U. S. hydropower capacity. The corps mission is to Deliver vital public and military engineering services, partnering in peace and war to strengthen our Nations security, energize the economy and their most visible missions include, Planning, designing, building, and operating locks and dams. Other civil engineering projects include flood control, beach nourishment, design and construction of flood protection systems through various federal mandates. Design and construction management of military facilities for the Army, Air Force, Army Reserve and Air Force Reserve and other Defense and Federal agencies. The history of United States Army Corps of Engineers can be traced back to 16 June 1775, colonel Richard Gridley became General George Washingtons first chief engineer, however, it was not until 1779 that Congress created a separate Corps of Engineers. One of its first tasks was to build fortifications near Boston at Bunker Hill, the first Corps of Engineers was mostly composed of French subjects who had been hired by General Washington from the service of Louis XVI. that the said Corps. Shall be stationed at West Point in the State of New York, until 1866, the superintendent of the United States Military Academy was always an officer of engineer. During the first half of the 19th century, West Point was the major and, for a while, the General Survey Act of 1824 authorized the use of Army engineers to survey road and canal routes. Separately authorized on 4 July 1838, the U. S and it was merged with the Corps of Engineers on 31 March 1863, at which point the Corps of Engineers also assumed the Lakes Survey District mission for the Great Lakes. In 1841, Congress created the Lake Survey, the survey, based in Detroit, Mich. was charged with conducting a hydrographical survey of the Northern and Northwestern Lakes and preparing and publishing nautical charts and other navigation aids. The Lake Survey published its first charts in 1852, in the mid-19th century, Corps of Engineers officers ran Lighthouse Districts in tandem with U. S. Naval officers. The Army Corps of Engineers played a significant role in the American Civil War, many of the men who would serve in the top leadership in this institution were West Point graduates who rose to military fame and power during the Civil War. Some of these men were Union Generals George McClellan, Henry Halleck, George Meade, and Confederate generals Robert E. Lee, Joseph Johnston, the versatility of officers in the Army Corps of Engineers contributed to the success of numerous missions throughout the Civil War. They were responsible for building pontoon and railroad bridges, forts and batteries, the destruction of supply lines. The Army Corps of Engineers served as a function in making the war effort logistically feasible. This method of building trenches was known as the zigzag pattern, from the beginning, many politicians wanted the Corps of Engineers to contribute to both military construction and works of a civil nature. During World War II the mission grew to more than 27,000 military, included were aircraft, tank assembly, and ammunition plants, camps for 5.3 million soldiers, depots, ports, and hospitals, as well as the Manhattan Project, and the Pentagon
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United States Forest Service
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The United States Forest Service is an agency of the U. S. Department of Agriculture that administers the nations 154 national forests and 20 national grasslands, which encompass 193 million acres. Major divisions of the include the National Forest System, State and Private Forestry, Business Operations. Managing approximately 25% of federal lands, it is the major national land agency that is outside the U. S. Department of the Interior. The concept of the National Forests was born from Theodore Roosevelt’s conservation group, Boone and Crockett Club, in 1876, Congress created the office of Special Agent in the Department of Agriculture to assess the quality and conditions of forests in the United States. Hough was appointed the head of the office, in 1881, the office was expanded into the newly formed Division of Forestry. The Forest Reserve Act of 1891 authorized withdrawing land from the domain as forest reserves. In 1901, the Division of Forestry was renamed the Bureau of Forestry, gifford Pinchot was the first United States Chief Forester in the Presidency of Theodore Roosevelt. As of 2009, the Forest Service has a budget authority of $5.5 billion. The Forest Service employs 34,250 employees in 750 locations, including 10,050 firefighters,737 law enforcement personnel, and 500 scientists. The mission of the Forest Service is To sustain the health, diversity and its motto is Caring for the land and serving people. As the lead agency in natural resource conservation, the US Forest Service provides leadership in the protection, management, and use of the nations forest, rangeland. The agencys ecosystem approach to management integrates ecological, economic, and social factors to maintain and enhance the quality of the environment to meet current, the everyday work of the Forest Service balances resource extraction, resource protection, and providing recreation.5 billion trees per year. Further, the Forest Service fought fires on 2,996,000 acres of land in 2007, the Forest Service organization includes ranger districts, national forests, regions, research stations and research work units and the Northeastern Area Office for State and Private Forestry. Each level has responsibility for a variety of functions, the Chief of the Forest Service is a career federal employee who oversees the entire agency. The Chief reports to the Under Secretary for Natural Resources and Environment in the U. S. Department of Agriculture, there are five deputy chiefs for the following areas, National Forest System, State and Private Forestry, Research and Development, Business Operations, and Finance. The Forest Service Research and Development deputy area includes five stations, the Forest Products Laboratory. Station directors, like regional foresters, report to the Chief, Research stations include Northern, Pacific Northwest, Pacific Southwest, Rocky Mountain, and Southern. There are 92 research work units located at 67 sites throughout the United States, there are 80 Experimental Forests and Ranges that have been established progressively since 1908, many sites are more than 50 years old
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United States Geological Survey
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The United States Geological Survey is a scientific agency of the United States government. The scientists of the USGS study the landscape of the United States, its resources. The organization has four science disciplines, concerning biology, geography, geology. The USGS is a research organization with no regulatory responsibility. The USGS is a bureau of the United States Department of the Interior, the USGS employs approximately 8,670 people and is headquartered in Reston, Virginia. The USGS also has major offices near Lakewood, Colorado, at the Denver Federal Center, the current motto of the USGS, in use since August 1997, is science for a changing world. The agencys previous slogan, adopted on the occasion of its anniversary, was Earth Science in the Public Service. Prompted by a report from the National Academy of Sciences, the USGS was created, by a last-minute amendment and it was charged with the classification of the public lands, and examination of the geological structure, mineral resources, and products of the national domain. This task was driven by the need to inventory the vast lands added to the United States by the Louisiana Purchase in 1803, the legislation also provided that the Hayden, Powell, and Wheeler surveys be discontinued as of June 30,1879. Clarence King, the first director of USGS, assembled the new organization from disparate regional survey agencies, after a short tenure, King was succeeded in the directors chair by John Wesley Powell. Administratively, it is divided into a Headquarters unit and six Regional Units, Other specific programs include, Earthquake Hazards Program monitors earthquake activity worldwide. The National Earthquake Information Center in Golden, Colorado on the campus of the Colorado School of Mines detects the location, the USGS also runs or supports several regional monitoring networks in the United States under the umbrella of the Advanced National Seismic System. The USGS informs authorities, emergency responders, the media, and it also maintains long-term archives of earthquake data for scientific and engineering research. It also conducts and supports research on long-term seismic hazards, USGS has released the UCERF California earthquake forecast. The USGS National Geomagnetism Program monitors the magnetic field at magnetic observatories and distributes magnetometer data in real time, the USGS operates the streamgaging network for the United States, with over 7400 streamgages. Real-time streamflow data are available online, since 1962, the Astrogeology Research Program has been involved in global, lunar, and planetary exploration and mapping. USGS operates a number of related programs, notably the National Streamflow Information Program. USGS Water data is available from their National Water Information System database
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Toronto
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Toronto is the most populous city in Canada and the provincial capital of Ontario. With a population of 2,731,571, it is the fourth most populous city in North America after Mexico City, New York City, and Los Angeles. A global city, Toronto is a centre of business, finance, arts, and culture. Aboriginal peoples have inhabited the area now known as Toronto for thousands of years, the city itself is situated on the southern terminus of an ancient Aboriginal trail leading north to Lake Simcoe, used by the Wyandot, Iroquois, and the Mississauga. Permanent European settlement began in the 1790s, after the broadly disputed Toronto Purchase of 1787, the British established the town of York, and later designated it as the capital of Upper Canada. During the War of 1812, the town was the site of the Battle of York, York was renamed and incorporated as the city of Toronto in 1834, and became the capital of the province of Ontario during the Canadian Confederation in 1867. The city proper has since expanded past its original borders through amalgamation with surrounding municipalities at various times in its history to its current area of 630.2 km2. While the majority of Torontonians speak English as their primary language, Toronto is a prominent centre for music, theatre, motion picture production, and television production, and is home to the headquarters of Canadas major national broadcast networks and media outlets. Toronto is known for its skyscrapers and high-rise buildings, in particular the tallest free-standing structure in the Western Hemisphere. The name Toronto is likely derived from the Iroquois word tkaronto and this refers to the northern end of what is now Lake Simcoe, where the Huron had planted tree saplings to corral fish. A portage route from Lake Ontario to Lake Huron running through this point, in the 1660s, the Iroquois established two villages within what is today Toronto, Ganatsekwyagon on the banks of the Rouge River and Teiaiagonon the banks of the Humber River. By 1701, the Mississauga had displaced the Iroquois, who abandoned the Toronto area at the end of the Beaver Wars, French traders founded Fort Rouillé on the current Exhibition grounds in 1750, but abandoned it in 1759. During the American Revolutionary War, the region saw an influx of British settlers as United Empire Loyalists fled for the British-controlled lands north of Lake Ontario, the new province of Upper Canada was in the process of creation and needed a capital. Dorchester intended the location to be named Toronto, in 1793, Governor John Graves Simcoe established the town of York on the Toronto Purchase lands, instead naming it after Prince Frederick, Duke of York and Albany. Simcoe decided to move the Upper Canada capital from Newark to York, the York garrison was constructed at the entrance of the towns natural harbour, sheltered by a long sandbar peninsula. The towns settlement formed at the end of the harbour behind the peninsula, near the present-day intersection of Parliament Street. In 1813, as part of the War of 1812, the Battle of York ended in the towns capture, the surrender of the town was negotiated by John Strachan. US soldiers destroyed much of the garrison and set fire to the parliament buildings during their five-day occupation, the sacking of York was a primary motivation for the Burning of Washington by British troops later in the war
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Wikisource
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Wikisource is an online digital library of free content textual sources on a wiki, operated by the Wikimedia Foundation. Wikisource is the name of the project as a whole and the name for each instance of that project, the projects aims are to host all forms of free text, in many languages, and translations. Originally conceived as an archive to store useful or important historical texts, the project officially began in November 24,2003 under the name Project Sourceberg. The name Wikisource was adopted later that year and it received its own domain name seven months later, the project has come under criticism for lack of reliability but it is also cited by organisations such as the National Archives and Records Administration. The project holds works that are either in the domain or freely licensed, professionally published works or historical source documents, not vanity products. Verification was initially made offline, or by trusting the reliability of digital libraries. Now works are supported by online scans via the ProofreadPage extension, some individual Wikisources, each representing a specific language, now only allow works backed up with scans. While the bulk of its collection are texts, Wikisource as a whole hosts other media, some Wikisources allow user-generated annotations, subject to the specific policies of the Wikisource in question. Wikisources early history included several changes of name and location, the original concept for Wikisource was as storage for useful or important historical texts. These texts were intended to support Wikipedia articles, by providing evidence and original source texts. The collection was focused on important historical and cultural material. The project was originally called Project Sourceberg during its planning stages, in 2001, there was a dispute on Wikipedia regarding the addition of primary source material, leading to edit wars over their inclusion or deletion. Project Sourceberg was suggested as a solution to this, perhaps Project Sourceberg can mainly work as an interface for easily linking from Wikipedia to a Project Gutenberg file, and as an interface for people to easily submit new work to PG. Wed want to complement Project Gutenberg--how, exactly, and Jimmy Wales adding like Larry, Im interested that we think it over to see what we can add to Project Gutenberg. It seems unlikely that primary sources should in general be editable by anyone -- I mean, Shakespeare is Shakespeare, unlike our commentary on his work, the project began its activity at ps. wikipedia. org. The contributors understood the PS subdomain to mean either primary sources or Project Sourceberg, however, this resulted in Project Sourceberg occupying the subdomain of the Pashto Wikipedia. A vote on the name changed it to Wikisource on December 6,2003. Despite the change in name, the project did not move to its permanent URL until July 23,2004, since Wikisource was initially called Project Sourceberg, its first logo was a picture of an iceberg
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Benchmarking (geolocating)
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Benchmarking is a hobby activity in which participants find benchmarks. They typically then log their finds online, like geocaching, the activity has become popular since about 1995, propelled by the availability of on-line data on the location of survey marks and by the rise of hobbyist-oriented websites. Many survey markers in the U. S. were set over 100 years ago, there was also a surge in creating these marks in the U. S. from about 1930 to 1955, in conjunction with the expansion of map-making activities across the country. In the U. S. some of these marks have precise adjusted coordinates, the ADJUSTED coordinates are precise to sub-centimeter accuracy, while others, typically true elevation Bench Marks, have only coordinates scaled from a map. SCALED coordinates were read from a map, rather than being surveyed. Many are accurate to 100 feet but some few are as much as 3,000 or 4,000 feet distant from the mark to which they refer, rendering a handheld GPS unit of little use in locating them. Most marks have clear to-reach descriptions, but some lack complete descriptions, or changes in the buildings, roads. Marks may have been removed by construction or buried, in the U. S. about 740,000 benchmarks with the most precise elevations or coordinates are listed in a database maintained by the National Geodetic Survey and accessible on-line. The majority of marks set by the U. S. Geological Survey, the Forest Service, the Corps of Engineers, or cities, and states, cadastral marks are usually not measured for the geodetic data base. The database used by Geocaching. com, the hobbyist website for U. S. benchmark hunters, is only a snapshot of the marks that the NGS had documented by the year 2000, and has not been updated since then. Each NGS-listed mark has a permanent identifier, a code that can be used to call up data about that mark. Using a form for an internet query like this, the PID for the mark can be entered, a data sheet obtained through such a query looks like this. There is also a website which uses Google Maps to show the locations of marks in each state of the U. S. Specialized hobbyist websites FAQ and its Benchmark Hunting forum can provide more information, in addition to the survey data sheet for a mark being hunted, many hunters bring along a digital camera to take close-up and area pictures of the survey mark. These photographs, as well as a current description of the mark by the person who finds the location of the mark, surveyors use the term recovering as a synonym for finding a mark. This does not mean that the mark should be disturbed in any way. On the contrary—disturbing a survey mark in even a small way often destroys its usefulness to surveyors and others, in the U. S. benchmark hunters often file two different reports on marks they find. One, less formal, is made to the website at Geocaching. com, handheld GPS receivers are often used to get within a few yards probable error of a mark that has adjusted coordinates
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Global Positioning System
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The Global Positioning System is a space-based radionavigation system owned by the United States government and operated by the United States Air Force. The GPS system operates independently of any telephonic or internet reception, the GPS system provides critical positioning capabilities to military, civil, and commercial users around the world. The United States government created the system, maintains it, however, the US government can selectively deny access to the system, as happened to the Indian military in 1999 during the Kargil War. The U. S. Department of Defense developed the system and it became fully operational in 1995. Roger L. Easton of the Naval Research Laboratory, Ivan A, getting of The Aerospace Corporation, and Bradford Parkinson of the Applied Physics Laboratory are credited with inventing it. Announcements from Vice President Al Gore and the White House in 1998 initiated these changes, in 2000, the U. S. Congress authorized the modernization effort, GPS III. In addition to GPS, other systems are in use or under development, mainly because of a denial of access. The Russian Global Navigation Satellite System was developed contemporaneously with GPS, GLONASS can be added to GPS devices, making more satellites available and enabling positions to be fixed more quickly and accurately, to within two meters. There are also the European Union Galileo positioning system and Chinas BeiDou Navigation Satellite System, special and general relativity predict that the clocks on the GPS satellites would be seen by the Earths observers to run 38 microseconds faster per day than the clocks on the Earth. The GPS calculated positions would quickly drift into error, accumulating to 10 kilometers per day, the relativistic time effect of the GPS clocks running faster than the clocks on earth was corrected for in the design of GPS. The Soviet Union launched the first man-made satellite, Sputnik 1, two American physicists, William Guier and George Weiffenbach, at Johns Hopkinss Applied Physics Laboratory, decided to monitor Sputniks radio transmissions. Within hours they realized that, because of the Doppler effect, the Director of the APL gave them access to their UNIVAC to do the heavy calculations required. The next spring, Frank McClure, the deputy director of the APL, asked Guier and Weiffenbach to investigate the inverse problem — pinpointing the users location and this led them and APL to develop the TRANSIT system. In 1959, ARPA also played a role in TRANSIT, the first satellite navigation system, TRANSIT, used by the United States Navy, was first successfully tested in 1960. It used a constellation of five satellites and could provide a navigational fix approximately once per hour, in 1967, the U. S. Navy developed the Timation satellite, which proved the feasibility of placing accurate clocks in space, a technology required by GPS. In the 1970s, the ground-based OMEGA navigation system, based on comparison of signal transmission from pairs of stations. Limitations of these systems drove the need for a more universal navigation solution with greater accuracy, during the Cold War arms race, the nuclear threat to the existence of the United States was the one need that did justify this cost in the view of the United States Congress. This deterrent effect is why GPS was funded and it is also the reason for the ultra secrecy at that time
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Levelling
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Levelling is a branch of surveying, the object of which is to Find the elevation of a given point with respect to the given or assumed datum. Establish a point at an elevation with respect to the given or assumed datum. Levelling is the measurement of geodetic height using an optical levelling instrument, common levelling instruments include the spirit level, the dumpy level, the digital level, and the laser level. Spirit levelling employs a spirit level, an instrument consisting of a telescope with a crosshair, when the bubble in the tube level is centered the telescopes line of sight is supposed to be horizontal. The spirit level is on a tripod with sight lines to the two points whose height difference is to be determined, a graduated leveling staff or rod is held vertical on each point, the rod may be graduated in centimetres and fractions or tenths and hundredths of a foot. The observer focuses in turn on each rod and reads the value, subtracting the back and forward value provides the height difference. If the instrument is placed equidistant from the two points to be measured, any errors in its adjustment and the effects of earth curvature. A typical procedure is to set up the instrument within 100 metres of a point of known or assumed elevation, a rod or staff is held vertical on that point and the instrument is used manually or automatically to read the rod scale. This gives the height of the instrument above the starting point, the rod is then held on an unknown point and a reading is taken in the same manner, allowing the elevation of the new point to be computed. The procedure is repeated until the point is reached. It is usual practice to either a complete loop back to the starting point or else close the traverse on a second point whose elevation is already known. The closure check guards against blunders in the operation, and allows residual error to be distributed in the most likely manner among the stations, some instruments provide three crosshairs which allow stadia measurement of the foresight and backsight distances. These also allow use of the average of the three readings as a check against blunders and for averaging out the error of interpolation between marks on the rod scale, the two main types of levelling are single-levelling as already described, and double-levelling. Double-levelling costs twice as much as single-levelling, the curvature of the earth means that a line of sight that is horizontal at the instrument will be higher and higher above a spheroid at greater distances. The effect may be significant for some work at distances under 100 meters, the line of sight is horizontal at the instrument, but is not a straight line because of refraction in the air. The change of air density with elevation causes the line of sight to bend toward the earth, for most work it is sufficient to keep the foresight and backsight distances approximately equal so that the refraction and curvature effects cancel out. Refraction is generally the greatest source of error in leveling, for short level lines the effects of temperature and pressure are generally insignificant, but the effect of the temperature gradient dT / dh can lead to errors. Assuming error-free measurements, if the Earths gravity field were completely regular and gravity constant, leveling loops would always close precisely, ∑ i =0 n Δ h i =0 around a loop
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Survey marker
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Survey markers, also called survey marks, survey monuments, or geodetic marks, are objects placed to mark key survey points on the Earths surface. They are used in geodetic and land surveying, informally, such marks are referred to as benchmarks, although strictly speaking the term benchmark is reserved for marks that indicate elevation. Horizontal position markers used for triangulation are also known as triangulation stations, all sorts of different objects, ranging from the familiar brass disks to liquor bottles, clay pots, and rock cairns, have been used over the years as survey markers. Some truly monumental markers have used to designate tripoints, or the meeting points of three or more countries. In the 19th century, these marks were often drill holes in rock ledges, crosses or triangles chiselled in rock and these marks are intended to be permanent, and disturbing them is generally prohibited by federal and state law. Such surveys laid the basis for map-making in the United States, Geodetic survey markers were often set in groups. For example, in surveys, the primary point identified was called the triangulation station. A triangulation station was surrounded by several reference marks, each of which bore an arrow that pointed back towards the main station. These reference marks made it easier for visitors to recover the primary mark. Reference marks also made it possible to replace a station mark that had been disturbed or destroyed, some old station marks were buried several feet down. Occasionally, these buried marks had surface marks set directly above them, in the U. S. survey marks that meet certain standards for accuracy are part of a national database that is maintained by the National Geodetic Survey. Each station mark in the database has a PID, a unique 6-character code that can be used to call up a datasheet describing that station, the NGS has a web-based form that can be used to access any datasheet, if the stations PID is known. Alternatively, datasheets can be called up by station name, a typical datasheet has either the precise or the estimated coordinates. Precise coordinates are called adjusted and result from precise surveys, estimated coordinates are termed scaled and have usually been set by locating the point on a map and reading off its latitude and longitude. Scaled coordinates can be as much as several feet distant from the true positions of their marks. Survey markers are now used to set up a GPS receiver antenna in a known position for use in Differential GPS surveying. Boundary marker Milestone No website will allow for searching of USGS Marks and this website provides a state-by-state mapping of NGS survey marks on to Google Maps, enabling one to search for these marks visually. Links to the listings on Geocaching. com are also provided
