International Meridian Conference
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 the recommendation of the Greenwich Meridian as the international standard for zero degrees longitude.
Local times in major towns across the United States, as published in 1857 when, as the document states, 'There is no "Standard Railroad Time" in the United States or Canada'.
A prime meridian is an arbitrarily-chosen meridian in a geographic coordinate system at which longitude is defined to be 0°. Together, a prime meridian and its anti-meridian form a great circle. This great circle divides a spheroid, like Earth, into two hemispheres: the Eastern Hemisphere and the Western Hemisphere. For Earth's prime meridian, various conventions have been used or advocated in different regions throughout history. Earth's current international standard prime meridian is the IERS Reference Meridian. It is derived, but differs slightly, from the Greenwich Meridian, the previous standard.
Gerardus Mercator in his Atlas Cosmographicae (1595) used a prime meridian somewhere close to 25°W, passing just to the west of Santa Maria Island in the Azores in the Atlantic Ocean. His 180th meridian runs along the Strait of Anián (Bering Strait)
The line of the Greenwich meridian at the Royal Observatory, Greenwich
