A time zone is a region of the globe that observes a uniform standard time for legal and social purposes. Time zones tend to follow the boundaries of countries and their subdivisions because it is convenient for areas in close commercial or other communication to keep the same time. Most of the time zones on land are offset from Coordinated Universal Time by a whole number of hours, but a few zones are offset by 30 or 45 minutes; some higher latitude and temperate zone countries use daylight saving time for part of the year by adjusting local clock time by an hour. Many land time zones are skewed toward the west of the corresponding nautical time zones; this creates a permanent daylight saving time effect. Before clocks were first invented, it was common practice to mark the time of day with apparent solar time – for example, the time on a sundial –, different for every location and dependent on longitude; when well-regulated mechanical clocks became widespread in the early 19th century, each city began to use some local mean solar time.
Apparent and mean solar time can differ by up to around 15 minutes because of the elliptical shape of the Earth's orbit around the Sun and the tilt of the Earth's axis. Mean solar time has days of equal length, the difference between the two sums to zero after a year. Greenwich Mean Time was established in 1675, when the Royal Observatory was built, as an aid to mariners to determine longitude at sea, providing a standard reference time while each city in England kept a different local time. Local solar time became inconvenient as rail transport and telecommunications improved, because clocks differed between places by amounts corresponding to the differences in their geographical longitudes, which varied by four minutes of time for every degree of longitude. For example, Bristol is about 2.5 degrees west of Greenwich, so when it is solar noon in Bristol, it is about 10 minutes past solar noon in London. The use of time zones accumulates these differences into longer units hours, so that nearby places can share a common standard for timekeeping.
The first adoption of a standard time was on December 1, 1847, in Great Britain by railway companies using GMT kept by portable chronometers. The first of these companies to adopt standard time was the Great Western Railway in November 1840; this became known as Railway Time. About August 23, 1852, time signals were first transmitted by telegraph from the Royal Observatory, Greenwich. Though 98% of Great Britain's public clocks were using GMT by 1855, it was not made Britain's legal time until August 2, 1880; some British clocks from this period have two minute hands—one for the local time, one for GMT. Improvements in worldwide communication further increased the need for interacting parties to communicate mutually comprehensible time references to one another; the problem of differing local times could be solved across larger areas by synchronizing clocks worldwide, but in many places that adopted time would differ markedly from the solar time to which people were accustomed. On November 2, 1868, the British colony of New Zealand adopted a standard time to be observed throughout the colony, was the first country to do so.
It was based on the longitude 172°30′ East of Greenwich, 11 hours 30 minutes ahead of GMT. This standard was known as New Zealand Mean Time. Timekeeping on the American railroads in the mid-19th century was somewhat confused; each railroad used its own standard time based on the local time of its headquarters or most important terminus, the railroad's train schedules were published using its own time. Some junctions served by several railroads had a clock for each railroad, each showing a different time. Charles F. Dowd proposed a system of one-hour standard time zones for American railroads about 1863, although he published nothing on the matter at that time and did not consult railroad officials until 1869. In 1870 he proposed four ideal time zones, the first centered on Washington, D. C. but by 1872 the first was centered with geographic borders. Dowd's system was never accepted by American railroads. Instead, U. S. and Canadian railroads implemented a version proposed by William F. Allen, the editor of the Traveler's Official Railway Guide.
The borders of its time zones ran through railroad stations in major cities. For example, the border between its Eastern and Central time zones ran through Detroit, Pittsburgh and Charleston, it was inaugurated on Sunday, November 18, 1883 called "The Day of Two Noons", when each railroad station clock was reset as standard-time noon was reached within each time zone. The zones were named Intercolonial, Central and Pacific. Within a year 85% of all cities with populations over 10,000, about 200 cities, were using standard time. A notable exception was Detroit which kept local time until 1900 tried Central Standard Time, local mean time, Eastern Standard Time before a May 1915 ordinance settled on EST and was ratified by popular vote in August 1916; the confusion of times came to an end when Standard zone time was formally adopted by the U. S. Congress in the Standard Time Act of March 19, 1918; the first known person to conceive of a worldwide system of time zones was the Italian mathematician
Dubeč is a municipal district and cadastral area in Prague. It is located in the eastern part of the city; as of 2008, there were 2,971 inhabitants living in Dubeč. The first written record of Dubeč is from the 11th century; the village became part of Prague in 1974. Praha-Dubeč - Official homepage
Prague 13 is a municipal district in Prague, Czech Republic. The administrative district of the same name consists of municipal districts Řeporyje. Prague 13 - Official homepage
Březiněves is a municipal district and cadastral area in Prague. It is located in the northern part of the city; as of 2008, there were 917 inhabitants living in Březiněves. The first written record of Březiněves is from the 12th century; the village became part of Prague in 1974 with the last enlargement of the city. Praha-Březiněves - Official homepage
Prague 1, formally the Prague 1 Municipal District, is a second-tier municipality in Prague. It is co-extensive with the national administrative district of the same name. Prague 1 includes most of the medieval heart of the city. All of Staré Město and Josefov are in the district, as are most of Malá Strana, Hradčany and Nové Město. Tiny parts of Holešovice and Vinohrady round out the district; the district has remained intact since its creation in 1960. Most of Prague 1 is a UNESCO World Heritage Site. All of Prague's major tourist sites, including Prague Castle, Old Town Square, the Charles Bridge and the above-mentioned Jewish Quarter, are in the district; the Parliament of the Czech Republic and the offices of the government are in Malá Strana, while the main building of Charles University is in Staré Město. As of the end of 2004, 32,552 people lived in 18,821 homes in the district; the district covers 5.53 km². A Prague 1 address is considered quite prestigious, real estate here is the most expensive in the city.
Filip Dvořák of the Civic Democratic Party is the current mayor of Prague 1. He was elected in 2009 to replace former mayor Petr Hejma; the Czech Ministry of Transport is in Prague 1. The Rail Safety Inspection Office has its head office in Prague 1; the Ministry of Foreign Affairs of the Czech Republic is headquartered in Czernin Palace in Prague 1. The Ministry of Education and Sports of the Czech Republic head office is in Prague 1. Prague 1 official site