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The International Meridian Conference was a conference held in October 1884 in Washington, D.C., in the United States, to determine a prime meridian for international use. The conference was held at the request of U.S. President Chester A. Arthur. The subject to discuss was the choice of "a meridian to be employed as a common zero of longitude and standard of time reckoning throughout the world".〔 It resulted in selection of the Greenwich Meridian as an international standard for zero degrees longitude.〔 ==Background== By the 1870s there was pressure both to establish a prime meridian for worldwide navigation purposes and to unify local times for railway timetables. The first International Geographical Congress, held in Antwerp in 1871, passed a motion in favour of the use of the Greenwich Meridian for (smaller scale) passage charts, suggesting that it should become mandatory within 15 years.〔 〕 In Britain, the Great Western Railway had standardised time by 1840 and in 1847 the ''Railway Clearing Union'' decreed that "GMT be adopted at all stations as soon as the General Post Office permitted it". The Post Office was by this time transmitting time signals from Greenwich by telegraph to most parts of the country to set the clocks. By January 1848, Bradshaw's railway guide showed the unified times and met with general approval, although legal disputes meant that it was not until 1890 that GMT was formally established across the UK. In the United States, the problems were much more severe, with one table showing over 100 local times varying by more than 3 hours. In 1870, Charles F. Dowd published a pamphlet titled ''A System of national time and its application'' advocating three time zones across the country based on the Washington meridian, modifying this to four zones based on the Greenwich meridian in 1872. The first proposal for a consistent treatment of time worldwide was a memoir entitled "''Terrestrial Time''" by Sanford Fleming, at the time the chief engineer of the Canadian Pacific Railway, presented to the Canadian Institute in 1876. This envisaged clocks showing 24-hour universal time with an extra dial having a local time rounded to the nearest hour.〔 〕 He also pointed out that many of the corrections for local mean time were greater than those involved in abandoning solar time. In 1878/9, he produced modified proposals using the Greenwich meridian. Fleming's two papers were considered so important that in June 1879 the British Government forwarded copies to eighteen foreign countries and to various scientific bodies in England. At the same time the ''American Metrological Society'' produced a "Report on Standard Time" by Cleveland Abbe, chief of the United States Weather Service proposing essentially the same scheme. These proposals did not meet universal approval in the scientific community, being opposed by John Rodgers, Superintendent of the Naval Observatory, Washington and British Astronomer Royal, George Airy who had both established wire services supporting local time in various cities. The Naval Observatory had also foiled the onward transmission of the Greenwich time signal from Harvard, where it was received via transatlantic cable and used to time a signal ball in Boston. The International Meridian Conference had its origins in the Third International Geographical Congress held in Venice in 1881, in which the establishment of a universal prime meridian and a uniform standard of time was high on the agenda. The Seventh ''International Geodesic Conference'' in Rome in October 1883 then thrashed out most of the technical details, leaving the diplomatic agreements to a later conference. The United States passed an Act of Congress on 3 August 1882 authorizing the President to call an international conference to fix on a common prime meridian for time and longitude throughout the world. Before the invitations were sent out on December 1, the joint efforts of Abbe, Fleming and William Frederick Allen, Secretary of the US railways' ''General Time Convention'' and Managing Editor of the ''Travellers' Official Guide to the Railways'', had brought the US railway companies to an agreement which led to standard railway time being introduced at noon on 18 November 1883 across the nation. Although this was not legally established until 1918, there was thus a strong sense of ''fait accompli'' that preceded the conference, although setting local times was not part of the remit of the conference. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「International Meridian Conference」の詳細全文を読む スポンサード リンク
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