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Maclear's Arc Measurement
Sir Thomas Maclear (17 March 1794 – 14 July 1879) was an Irish-born South African astronomer who became Her Majesty's astronomer at the Cape of Good Hope. Life He was born in Newtownstewart, County Tyrone, Ireland, the eldest son of Rev James Maclear and Mary Magrath. In 1808 he was sent to England to be educated in the medical profession. After passing his examinations, in 1815 he was accepted into the Royal College of Surgeons of England. He then worked as house-surgeon in the Bedford Infirmary. In 1823 he went into partnership with his uncle at Biggleswade, Bedfordshire. Two years later in 1825 he was married to Mary Pearse, the daughter of Theed Pearse, Clerk of the Peace for the county of Bedford. Maclear had a keen interest in amateur astronomy, and would begin a long association with the Royal Astronomical Society, to which he would be named a Fellow. In 1833, when the post became vacant, he was named as Her Majesty's Astronomer at the Cape of Good Hope, and arrived ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Newtownstewart
Newtownstewart is a village and townland of in County Tyrone, Northern Ireland. It is overlooked by hills called Bessy Bell and Mary Gray and lies on the River Strule below the confluence with its tributary the Owenkillew. It is situated in the historic barony of Strabane Lower and the civil parish of Ardstraw. In the 2011 Census it had a population of 1,551 people. This article contains quotations from this source, which is available under th Open Government Licence v3.0. © Crown copyright. It lies within the Derry City and Strabane District Council area. History The townland of Newtownstewart was historically called ''Lislas''. Newtownstewart Castle was built by Sir Robert Newcomen in 1615 as part of the Plantation of Ulster. The castle was acquired by Sir William Stewart when he married Newcommen's second daughter in 1629. The castle and town were renamed Newtownstewart by Sir William Stewart after his birthplace. The former Northern Bank building on the corner was ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Figure Of The Earth
Figure of the Earth is a Jargon, term of art in geodesy that refers to the size and shape used to model Earth. The size and shape it refers to depend on context, including the precision needed for the model. A Spherical Earth, sphere is a well-known historical approximation of the figure of the Earth that is satisfactory for many purposes. Several models with greater accuracy (including Earth ellipsoid, ellipsoid) have been developed so that Geographic coordinate system, coordinate systems can serve the precise needs of navigation, surveying, cadastre, land use, and various other concerns. Motivation Earth's Topography, topographic surface is apparent with its variety of land forms and water areas. This topographic surface is generally the concern of topographers, Hydrography, hydrographers, and Geophysics, geophysicists. While it is the surface on which Earth measurements are made, mathematically modeling it while taking the irregularities into account would be extremely compl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Maclear, Eastern Cape
Nqanqarhu (formerly Maclear) is a small town situated in the Eastern Cape province of South Africa, near the Mooi River (a tributary of the Tsitsa River), north of East London and northeast of Elliot. It was founded in 1876 as a military camp, called ''Nqanqaru Drift'' and developed rapidly, reaching municipal status in 1916. It is named after Sir Thomas Maclear (1794-1879), a famous astronomer who laid the foundation for a trigonometrical survey of the Cape Colony. It lies just north-east of Ugie. The land to the east and south was part of the former homeland of Transkei. Tourism Maclear is a trout-fishing resort. Geographic location Maclear lies between Mount Fletcher and Ugie, in the foothills of the Drakensberg The Drakensberg (Afrikaans: Drakensberge, Zulu: uKhahlambha, Sotho: Maluti) is the eastern portion of the Great Escarpment, which encloses the central Southern African plateau. The Great Escarpment reaches its greatest elevation – within th ... mountains, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Moon
The Moon is Earth's only natural satellite. It is the fifth largest satellite in the Solar System and the largest and most massive relative to its parent planet, with a diameter about one-quarter that of Earth (comparable to the width of Australia). The Moon is a planetary-mass object with a differentiated rocky body, making it a satellite planet under the geophysical definitions of the term and larger than all known dwarf planets of the Solar System. It lacks any significant atmosphere, hydrosphere, or magnetic field. Its surface gravity is about one-sixth of Earth's at , with Jupiter's moon Io being the only satellite in the Solar System known to have a higher surface gravity and density. The Moon orbits Earth at an average distance of , or about 30 times Earth's diameter. Its gravitational influence is the main driver of Earth's tides and very slowly lengthens Earth's day. The Moon's orbit around Earth has a sidereal period of 27.3 days. During each synodic period ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Maclear (crater)
Maclear is a lava-flooded crater on the northwest part of the Mare Tranquillitatis, a lunar mare in the eastern half of the Moon. Its diameter is 20 km. The crater is located to the southwest of the slightly larger Ross. To the southwest of Maclear is Sosigenes, while farther to the south-southeast is Arago. With most of its interior submerged in deposits of basaltic lava, all that remains of this crater is a narrow rim projecting above the surrounding mare. The rim is not quite circular, having a flat outward bulge along the western side. But the rim is relatively uniform in width and is not significantly eroded. The crater rim lies at the southern terminus of a rille belonging to a system that runs along the western edges of Mare Tranquillitatis. The rille system to the north of the crater is designated Rimae Maclear, while the rilles to the south-southwest are named Rimae Sosigenes. The Rimae Maclear stretches for about 100 kilometers, reaching Al-Bakri to the north a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Arc Of The Meridian
In geodesy and navigation, a meridian arc is the curve between two points on the Earth's surface having the same longitude. The term may refer either to a segment of the meridian, or to its length. The purpose of measuring meridian arcs is to determine a figure of the Earth. One or more measurements of meridian arcs can be used to infer the shape of the reference ellipsoid that best approximates the geoid in the region of the measurements. Measurements of meridian arcs at several latitudes along many meridians around the world can be combined in order to approximate a ''geocentric ellipsoid'' intended to fit the entire world. The earliest determinations of the size of a spherical Earth required a single arc. Accurate survey work beginning in the 19th century required several arc measurements in the region the survey was to be conducted, leading to a proliferation of reference ellipsoids around the world. The latest determinations use astro-geodetic measurements and the meth ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Thomas Maclear 1860
Thomas may refer to: People * List of people with given name Thomas * Thomas (name) * Thomas (surname) * Saint Thomas (other) * Thomas Aquinas (1225–1274) Italian Dominican friar, philosopher, and Doctor of the Church * Thomas the Apostle * Thomas (bishop of the East Angles) (fl. 640s–650s), medieval Bishop of the East Angles * Thomas (Archdeacon of Barnstaple) (fl. 1203), Archdeacon of Barnstaple * Thomas, Count of Perche (1195–1217), Count of Perche * Thomas (bishop of Finland) (1248), first known Bishop of Finland * Thomas, Earl of Mar (1330–1377), 14th-century Earl, Aberdeen, Scotland Geography Places in the United States * Thomas, Illinois * Thomas, Indiana * Thomas, Oklahoma * Thomas, Oregon * Thomas, South Dakota * Thomas, Virginia * Thomas, Washington * Thomas, West Virginia * Thomas County (other) * Thomas Township (other) Elsewhere * Thomas Glacier (Greenland) Arts, entertainment, and media * ''Thomas'' (Burton novel) 1969 nove ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Royal Observatory, Cape Of Good Hope
The Royal Observatory, Cape of Good Hope, is the oldest continuously existing scientific institution in South Africa. Founded by the British Board of Longitude in 1820, it now forms the headquarters building of the South African Astronomical Observatory. The institution was located on a small hill south-east from the centre of Cape Town. Over the following century a suburb of the city grew up in the area; the suburb was named Observatory after the pre-existing Royal Observatory. It was declared a National Heritage Site in December 2018 and has also been the subject of an ICOMOS/IAU Case Study as a World Heritage Site. History The proposal for a Southern observatory in all likelihood originated among the same group of people who founded the Royal Astronomical Society in the United Kingdom. The official establishment of the Royal Observatory, Cape of Good Hope took place on 20 October 1820 through an Order in Council of King George IV of the United Kingdom. It remained a sep ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Africa
Africa is the world's second-largest and second-most populous continent, after Asia in both cases. At about 30.3 million km2 (11.7 million square miles) including adjacent islands, it covers 6% of Earth's total surface area and 20% of its land area.Sayre, April Pulley (1999), ''Africa'', Twenty-First Century Books. . With billion people as of , it accounts for about of the world's human population. Africa's population is the youngest amongst all the continents; the median age in 2012 was 19.7, when the worldwide median age was 30.4. Despite a wide range of natural resources, Africa is the least wealthy continent per capita and second-least wealthy by total wealth, behind Oceania. Scholars have attributed this to different factors including geography, climate, tribalism, colonialism, the Cold War, neocolonialism, lack of democracy, and corruption. Despite this low concentration of wealth, recent economic expansion and the large and young population make Afr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
David Livingstone
David Livingstone (; 19 March 1813 – 1 May 1873) was a Scottish physician, Congregationalist, and pioneer Christian missionary with the London Missionary Society, an explorer in Africa, and one of the most popular British heroes of the late 19th-century Victorian era. David was the husband of Mary Moffat Livingstone, from the prominent 18th Century missionary family, Moffat. He had a mythic status that operated on a number of interconnected levels: Protestant missionary martyr, working-class "rags-to-riches" inspirational story, scientific investigator and explorer, imperial reformer, anti-slavery crusader, and advocate of British commercial and colonial expansion. Livingstone's fame as an explorer and his obsession with learning the sources of the Nile River was founded on the belief that if he could solve that age-old mystery, his fame would give him the influence to end the East African Arab–Swahili slave trade. "The Nile sources", he told a friend, "are valuabl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
De Lacaille's Arc Measurement
Abbé Nicolas-Louis de Lacaille (; 15 March 171321 March 1762), formerly sometimes spelled de la Caille, was a French astronomer and geodesist who named 14 out of the 88 constellations. From 1750 to 1754, he studied the sky at the Cape of Good Hope in present-day South Africa. Lacaille observed over 10,000 stars using just a half-inch refracting telescope. Biography Born at Rumigny in the Ardennes in eastern France, he attended school in Mantes-sur-Seine (now Mantes-la-Jolie). Afterwards, he studied rhetoric and philosophy at the Collège de Lisieux and then theology at the Collège de Navarre. He was left destitute in 1731 by the death of his father, who had held a post in the household of the duchess of Vendôme. However, he was supported in his studies by the Duc de Bourbon, his father's former patron. After he graduated, he did not accept ordination as a priest but took deacon's orders, becoming an Abbé. He concentrated thereafter on science, and, through the patr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Triangulation (surveying)
In surveying, triangulation is the process of determining the location of a point by measuring only angles to it from known points at either end of a fixed baseline by using trigonometry, rather than measuring distances to the point directly as in trilateration. The point can then be fixed as the third point of a triangle with one known side and two known angles. Triangulation can also refer to the accurate surveying of systems of very large triangles, called triangulation networks. This followed from the work of Willebrord Snell in 1615–17, who showed how a point could be located from the angles subtended from ''three'' known points, but measured at the new unknown point rather than the previously fixed points, a problem called resectioning. Surveying error is minimized if a mesh of triangles at the largest appropriate scale is established first. Points inside the triangles can all then be accurately located with reference to it. Such triangulation methods were used for accur ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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