The International Meridian Conference

Washington DC, USA - October 1884

Why is Greenwich the "centre of time and space"?

Why does the Prime Meridian (Zero Longitude) pass through Greenwich?

It dates back to October 1884. At the behest of the President of the United States of America 41 delegates from 25 nations met in Washington, DC, USA for the International Meridian Conference.

At the Conference the following important principles were established:

  1. It was desirable to adopt a single world meridian to replace the numerous ones already in existence.
  2. The Meridian passing through the principal Transit Instrument at the Observatory at Greenwich was to be the 'initial meridian'.
  3. That all longitude would be calculated both east and west from this meridian up to 180°.
  4. All countries would adopt a universal day.
  5. The universal day would be a Mean Solar Day, beginning at the Mean Midnight at Greenwich and counted on a 24 hour clock.
  6. That nautical and astronomical days everywhere would begin at mean midnight.
  7. All technical studies to regulate and extend the application of the decimal system to the division of time and space would be supported.

Resolution 2, fixing the Meridian at Greenwich was passed 22-1 (San Domingo voted against), France & Brazil abstained.

The National Maritime Museum have kindly given us extracts from the Conference minutes

A list of the Nations attending and their delegates is here

Full text of the seven Final Act Resolutions and voting is here