![]() ![]() ![]() Greenwich was chosen for two important reasons: Twenty-five nations attended the conference in total, and with a vote of 22 to 1 (San Domingo was against and France and Brazil abstained from voting), Greenwich was chosen as the Prime Meridian of the World. by invitation of Chester Arthur, twenty-first President of the United States, to establish one prime meridian with a longitude of 0° 0′ 0” by which every location would be measured in relation to its distance east or west, dividing the east and western hemispheres. In October 1884, an International Meridian Conference was held in Washington D.C. The advent of the industrial age in the mid – late nineteenth century, which brought with it the railway and increased international communications, meant an international time standard was needed. This meant that beginning and end of the day and the length of an hour varied from town to town and country to country. Until the end of the nineteenth century, there were no national or international guidelines for measuring time. Greenwich Mean Time (GMT) was established in 1884 when, at the International Meridian Conference, it was decided to place the Prime Meridian at Greenwich, England. Intrinsically linked to the measurement of longitude is the measurement of time. ![]() However, it was not until 1773 that the Board awarded the prize to John Harrison, a joiner and watchmaker from Yorkshire, for his mechanical timepiece the marine chronometer, which overtook the lunar method in its popularity for establishing longitude with nineteenth century sailors. In 1714 Parliament assembled a group of experts known as the Board of Longitude and provided an unthinkably large £20,000 prize (approximately £2 million in today’s money) to anyone able to find a solution for measuring longitude at sea. This terrible disaster occurred off the Isles of Scilly on 22 October 1707 and resulted in the deaths of over 1400 British sailors because of their inability to accurately calculate their ship’s position. The Scilly naval disaster prompted further action in the pursuit of measuring longitude. These calculations, known as the ‘Lunar Distance Method’, were later published in the Nautical Almanac and referred to by sailors to establish Greenwich Time, which in turn allowed them to work out their current longitude. The observatory was to be used to produce an accurate catalogue of the positions of the stars, which correspondingly would allow the Moon’s position to be accurately measured. The astronomer John Flamsteed was appointed by the king as his first ‘Astronomer Royal’ in charge of the observatory in March of the same year. In 1675, in the midst of the reformation period, King Charles II founded the Greenwich Observatory in the Crown-owned Greenwich Park, south east London, to improve naval navigation and establish longitude measurements using astronomy. It was establishing the time at another location that was the problem. As such, whilst sailors could measure the local time of their location by studying the Sun, they would also need to know the local time of a reference point in a different location to calculate their longitude. It was known that longitude could be calculated using the difference in local times of two points on the Earth’s surface. This included such locations as the Canary Island of El Hierro and St Paul’s Cathedral! However, the increase in international travel and trade made it necessary for a move towards the unification of co-ordinates in the seventeenth century. Prior to the 17th century, countries chose their own location by which to measure from east to west across the world. People flock from all over the world to stand with one foot in each of the eastern and western hemispheres! It is the line from which all other lines of longitude are measured. The line runs across the floor in the courtyard there. ![]() The Greenwich Meridian line, Longitude 0°, runs through the historic Airy Transit Circle telescope, which is housed at the Royal Observatory at Greenwich in south-east London. It is an imaginary line which runs from the North Pole to the South Pole and passes through England, France, Spain, Algeria, Mali, Burkina Faso, Togo, Ghana and Antarctica. The Greenwich Meridian separates east from west in the same way that the Equator separates north from south. ![]()
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