On October 1, 1884, forty-one delegates from 25 nations assembled at the Diplomatic Hall in Washington D.C at the invitation of the US President, Chester Arthur, their mission to establish the Prime Meridian. As it travels around the Sun the Earth rotates on its axis in a counterclockwise direction (from west to east), meaning that different parts of the globe receive the Sun’s direct rays at different times. The boom in global commerce, the growing interdependency between nations, and the increasing sophistication of communications systems meant that it was imperative that all clocks were set to a world standard.

The delegates voted by 22 votes to one to accept the meridian passing through the Observatory at Greenwich as the Prime Meridian from which all longitudes would be calculated both east and west until the 180⁰ meridian was reached. There would be twenty-four time zones of 15 degrees each, twelve running eastwards from the Greenwich meridian to the 180⁰ point and twelve westwards. All countries would adopt a universal day, lasting twenty-four hours, beginning at midnight in Greenwich and counted on a 24-hour clock.

San Domingo, now Dominican Republic, voted against Greenwich being the Prime Meridian with Brazil and France abstaining, the latter not adopting the Greenwich meridian on their maps until 1911.

The conference also selected the 180⁰ meridian as the location for the International Date Line (IDL), marking the boundary between one calendar day and the next, passing through the sparsely populated Central Pacific Ocean and causing, at least to western eyes, least inconvenience. Crossing the IDL eastwards decreases the date by one while crossing it westwards advances it by one. Never defined in international law, it runs an erratic path on a map, as countries through whose waters it passes have moved it for their convenience.

One of the most recent examples was Samoa which effectively erased December 30, 2011 from the country’s calendar when it crossed westwards over the IDL. Crowds gathered around the main clock tower in the capital, Appia, and cheered as the clock struck midnight on December 29^th, instantly transporting them to New Year’s Eve. Geographical proximity creates some oddities. Just two miles of the Bering Sea separate Big Diomede Island, part of Russia, from Little Diomede, part of the US, as the IDL passes between the two, the Russian territory is always one day ahead.       

For sailors and passengers alike crossing the IDL was a high water mark in a voyage across the expanse of the Pacific Ocean. One to experience the sensation was Mark Twain who in 1895 was travelling on the SS Warrimoo, sailing from Vancouver to Sydney, at the start of a world lecture tour to restore his finances after an unwise investment. In Following the Equator (1897) he described the moment, characteristically pointing out the absurdities that arose.

“While we were crossing the 180^th meridian”, he wrote, “it was Sunday in the stern of the ship where my family were, and Tuesday on the bow where I was. They were there eating half of a fresh apple on the 8^th, and I was at the same time eating the other half of it on the 10^th – and I could notice how stale it was, already”.

A child was born in steerage at the precise moment, he reported, and there was no way to tell which day it was born on. “The nurse thinks it was Sunday, the surgeon thinks it is Tuesday”. Twain feared for the child’s future, surmising that the doubts as to its birth date will lead to “vacillation and uncertainty in its opinions about religion and politics, and business, and sweethearts” making it characterless and impossible for it to make a success in life.