<Table> <Tr> <Td> </Td> <Td> This article needs additional citations for verification . Please help improve this article by adding citations to reliable sources . Unsourced material may be challenged and removed . (July 2018) (Learn how and when to remove this template message) </Td> </Tr> </Table> <Tr> <Td> </Td> <Td> This article needs additional citations for verification . Please help improve this article by adding citations to reliable sources . Unsourced material may be challenged and removed . (July 2018) (Learn how and when to remove this template message) </Td> </Tr> <P> A (geographical) meridian (or line of longitude) is the half of an imaginary great circle on the Earth's surface, terminated by the North Pole and the South Pole, connecting points of equal longitude . The position of a point along the meridian is given by its latitude indicating how many degrees north or south of the Equator the point is . Each meridian is perpendicular to all circles of latitude . Each is also the same length, being half of a great circle on the Earth's surface and therefore measuring 20,003.93 km (12,429.9 miles). </P> <P> The first prime meridian was set by Eratosthenes in 276 BCE . This prime meridian was used to provide measurement of the earth, but had many issues because of the lack of latitude measurement . Many years later around the 19th century there was still concerns of the prime meridian . The idea of having one prime meridian came from William Parker Snow, because he realized the confusion of having multiple prime meridian locations . Many of theses geographical locations were traced back to the ancient Greeks, and others were created by several nations . Multiple locations for the geographical meridian meant that there was inconsistency, because each country had their own guidelines for where the prime meridian was located . </P>

What is the meaning of meridian in geography
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