24-hour Clock - History

History

The 24-hour time system has been used for centuries, primarily by scientists, astronomers, navigators, and horologists. There are many surviving examples of clocks built using the 24-hour system, including the famous Orloj in Prague, and the Shepherd gate clock at Greenwich.

At the International Meridian Conference in 1884, Sandford Fleming proposed:

That this universal day is to be a mean solar day; is to begin for all the world at the moment of mean midnight of the initial meridian, coinciding with the beginning of the civil day and date of that meridian; and is to be counted from zero up to twenty-four hours.

This resolution was adopted by the conference.

According to a report in the London Times in 1886, the 24-hour clock was in use on the Canadian Pacific Railway train at Port Arthur.

The earliest country to introduce the 24-hour system nationally was Italy, in 1893. Other European countries followed: France adopted it in 1912 (the French army in 1909), followed by Denmark (1916), and Greece (1917). By 1920, Spain, Portugal, Belgium, and Switzerland had switched, followed by Turkey (1925), and Germany (1927). By the early 1920s, many countries in Latin America had also adopted the 24-hour clock. Some of the railways in India had switched before the outbreak of the war.

During World War I, the British Royal Navy adopted the 24-hour clock in 1915, and the Allied armed forces followed soon after, with the British Army switching officially in 1918. The Canadian armed forces first started to use the 24-hour clock in late 1917. In 1920, the US Navy was the first US organization to adopt the system; the US Army, however, did not officially adopt the 24-hour clock until World War II, on July 1, 1942.

In Britain, the use of the 24-hour clock in daily life has grown steadily since the beginning of the 20th century, although attempts to make the system official failed more than once. In 1934, the BBC switched to the 24-hour clock for broadcast announcements and programme listings. The experiment was halted after five months following a lack of enthusiasm from the public, and the BBC has used the 12-hour clock ever since. In the same year, the US airlines Pan American World Airways Corporation and Western Airlines both adopted the 24-hour clock.

British Rail and London Transport switched to the 24-hour clock for timetables in 1964.

In 2005, BBC Weather television forecasts used the 12-hour notation for several months after its graphical revamp. After complaints from the public, however, this was switched to 24-hour notation.