#63 Science in History
2nd August 1880
On this day in 1880, Parliament officially recognised and adopted Greenwich Mean Time (GMT). The Statutes (Definition of Time) Act of 1880 defined GMT as the legal standard time for the United Kingdom and established the beginning of each day at midnight, a practice still followed today.
Greenwich Mean Time (GMT) had been established 200 years earlier at the Royal Observatory in Greenwich, London. in 1675. Sir Christopher Wren commissioned the construction of the observatory, and it was completed under the supervision of John Flamsteed, the first Astronomer Royal. The main purpose of the observatory was to improve navigation at sea by accurately determining longitude, a challenging task for sailors at the time.
To accomplish this, Flamsteed and subsequent Astronomers Royal made precise astronomical observations, particularly of the stars, to determine the local time at the Prime Meridian, which passes through Greenwich. The mean solar time at the observatory was taken as the reference time for GMT, and it was published regularly for navigators and the public. GMT quickly became the standard time for Britain, and sailors around the world used it to set their chronometers. By the 18th century, GMT had become widely adopted by seafaring nations as the reference time for maritime navigation.
Before the widespread use of GMT, navigators relied on local timekeeping methods that varied from port to port, causing significant confusion and inaccuracies. The introduction of GMT and the ability to determine longitude accurately revolutionized maritime travel, making voyages much safer and more efficient.
In the 19th century, with the rise of global trade and communication, the need for standardized timekeeping beyond the borders of Britain became evident. In 1847, the Great Western Railway in Britain adopted GMT as the standard time for its timetables, which further popularised the use of GMT across the country.
The legal recognition of GMT by the British Parliament laid the groundwork for the international adoption of time zones. In 1884, the International Meridian Conference was held in Washington, D.C., where representatives from 25 countries gathered to establish a system of 24 time zones, each one an hour apart, and centred on the Prime Meridian at Greenwich. This marked the birth of the modern time zone system and solidified GMT's role as the basis for global timekeeping.
During the late 19th and early 20th centuries, Ruth Belville and her father, John Belville, were known as "The Greenwich Time Lady" and "The Greenwich Time Man," respectively, for providing time-setting services in London. Their clients included the Stock Exchange, shipping companies, railway companies, astronomers, scientists, and even the Royal Observatory itself. The Belvilles' accurate timekeeping service was highly sought after during an era when reliable time was crucial for various aspects of life and business. Ruth Belville continued the family tradition after her father's death and earned a reputation as a reliable timekeeper, serving clients until her own passing in 1943.
Many countries around the world gradually adopted standardised time zones, using GMT as a reference. However, as technology advanced, more precise time standards were developed, leading to the establishment of Coordinated Universal Time (UTC) in the 1960s. UTC is based on atomic time, which is more stable and accurate than GMT's reliance on the Earth's rotation. Today, UTC serves as the primary reference for global timekeeping, and it is kept precise through a network of atomic clocks around the world.
Despite the prevalence of UTC, GMT remains historically significant and holds a place of reverence in the history of timekeeping. The Royal Observatory in Greenwich, where GMT was established, continues to attract visitors from all over the world, and it is recognised as a UNESCO World Heritage Site.
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