The meridian of Rome and the first time zone world map One of the minute hand was for the local time and the other one for GMT. Clocks with 2 minutes hands was common at that period. By 1855, 98% of the Great Britain’s public clocks were using GMT, but it was still not Britain’s legal time until 2 August 1880. Then around the 23 august 1852, the Royal Observatory of Greenwich emitted time signals for the first time by telegraph. This quickly became known as Railway Time. The first company to adopt the standard time was the Great Western Railway (GWR).

The first adoption of a standard time zone was established in Great Britain on November 1840 using the GMT kept by portable chronometers. For example, when it is solar noon in Bristol, it is about 10 minutes past solar noon in London. The variation of time with the geographical longitudes is about 4 minutes by degree of longitude in the United Kingdom. With the development of transport and telecommunications, local solar time starts to become increasingly inconvenient, because clocks differed between places in function of the geographical longitude. Railway time: the first standard time zone Most time zones were based upon GMT, as an offset of a number of hours (and also half or quarter hours) ahead of GMT or behind GMT. The GMT start to become a standard time independent location because of this practice and the use of mariners from other nations of the lunar distances based on observations at Greenwich. The convention from the International Meridian Conference of 1884 set the Greenwich meridian as the longitude zero degrees. To calculate the longitude from the Greenwich meridian, British mariners kept at least one chronometer on GMT. It was an aid to mariners to determine longitude at sea, providing a standard reference time while each city in England kept a different local time. The Greenwich Mean Time (GMT) was established in 1675 when the Royal Observatory was built. In the 15th century we started to have the first table clocks and even the first watch with ringing clocks on costume of people at the end of the 15th century. In the 14th century, the church towers across Europe had clocks so that they were visible for everyone.Īcross the 15th century, improvements and miniaturisation continues. Further improvement will simplifying the 24 parts in 12 parts for readability. In the beginning, it is the 24 hours that will move and then it will be fixed and only the clock hand for the hour will move. Later the technical advances have allowed to display the 24 hours. At the beginning these clocks were only there to ring 24 times the bell (for the 24 hours). They were only frequent in monastery and cathedrals. At that time, there was a very limited number of water and mechanical clocks. The mechanical clocks appear around the end of the 13th century. The time zones are numbered in relation to the UTC, so in Los Angeles the time zone will be UTC−8, in London UTC+0, in Rome UTC+1, and in New Delhi UTC+5:30.Before the the clock was invented, people were measuring time with different early measuring device like sundials and water clocks. In the poles, the time is UTC in the North Pole and UTC+12 in the South Pole. In some parts of the world they follow the Daylight Saving Time (DST), and during this period of time in summer they add one hour to their normal solar hour. Most of the zones are offset by a full hour, but there are some offset by half an hour or 45 minutes. All other parts of the world are offset (plus or minus) according to their longitude. Greenwich Mean Time is now called UTC ( Coordinated Universal Time). By about 1900, almost all time on earth was in the form of standard time zones. When railways began carrying many people quickly among cities keeping different time, they adopted time zones to simplify operations. GMT was a standard reference for time keeping when each city kept a different local time. This was when the Royal Observatory, Greenwich was built to help ships find their longitude at sea. The North American Eastern Time Zone contains large cities in North America like New York City and Miami.

There are 24 time zones dividing the earth into different times, each with its own name, like the North American Eastern Time Zone. This is because when it is daytime on one side of the earth, it is night-time on the other side. Time zones give specific areas on the Earth a time of day that is earlier or later than the neighboring time zones. Standard World Time Zones map (as of August 2015)

Gmt time zone definition