Meridian Crisis Resolved with Greenwich

October 13, 2011 | posted in: Tech Chronicles | by

The Prime Meridian, looking directly North. Photo courtesy of

Technology that Shapes Our Lives

October 13, 1884

Geographers and astronomers adopt Greenwich as the Prime Meridian, the international standard for zero degrees longitude.

Prior to the adoption of a standard Prime Meridian, navigation at sea — and the charting of stars in the heavens — often remained a matter of local, national or even religious preference. Maps might be based on longitude east or west of Jerusalem, Saint Petersburg, Rome, Pisa, Copenhagen, Oslo, Paris, Greenwich (just east of central London), El Hierro (in the Canary Islands), Philadelphia (former U.S. capital) and Washington, D.C. These divergent reference meridians — representing a mixture of astronomical, theological and maritime power — ranged over 112 degrees of longitude.

In the interests of global amity — and commerce — U.S. President Chester Alan Arthur convened the International Meridian Conference in Washington in 1884. Delegates from 25 countries attended.

The conference set out to select a Prime Meridian for the world. The United States, rising power of the Western Hemisphere, had already adopted the Greenwich Meridian for navigation, and 72 percent of the world’s commerce used nautical charts based on Greenwich.

Britain had first solved the problem of longitude, Britain had the world’s largest navy, and the sun indeed did not set on the far-flung British Empire. Britannia ruled the waves, so there was no need for Britain to waive its rules.

Thus, the conference established that the meridian passing through the Royal Observatory at Greenwich would be the world’s Prime Meridian, and all longitude would be calculated both east and west from it up to 180 degrees. The conference also established Greenwich Mean Time as a standard for astronomy and setting time zones.

The vote to select Greenwich passed 22 to 1. San Domingo (now the Dominican Republic) voted against. France and Brazil, diplomatically, abstained.

About the Author