121-560: The Chatham Standard Time Zone is a time zone twelve hours and forty-five minutes ahead of Coordinated Universal Time (UTC) resulting in UTC+12:45 . It is used exclusively in the Chatham Islands , New Zealand. It is one of three time zones with a 45-minute offset from UTC, the others being Nepal Standard Time ( UTC+05:45 ) and the unofficial Australian Central Western Time ( UTC+08:45 ). During summer, daylight saving time
242-567: A diplomatic cable , is a confidential communication between a diplomatic mission and the foreign ministry of its parent country. These continue to be called telegrams or cables regardless of the method used for transmission. Passing messages by signalling over distance is an ancient practice. One of the oldest examples is the signal towers of the Great Wall of China . In 400 BC , signals could be sent by beacon fires or drum beats . By 200 BC complex flag signalling had developed, and by
363-426: A 30-minute offset. Nepal was the last country to adopt a standard offset, shifting slightly to UTC+05:45 in 1986. All nations currently use standard time zones for secular purposes, but not all of them apply the concept as originally conceived. Several countries and subdivisions use half-hour or quarter-hour deviations from standard time. Some countries, such as China and India , use a single time zone even though
484-564: A C library based on the BSD C library, or the System V Release 4 C library, can make use of this database. Windows -based computer systems prior to Windows 95 and Windows NT used local time, but Windows 95 and later, and Windows NT, base system time on UTC. They allow a program to fetch the system time as UTC, represented as a year, month, day, hour, minute, second, and millisecond; Windows 95 and later, and Windows NT 3.5 and later, also allow
605-574: 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 time zones were formally adopted by the U.S. Congress in the Standard Time Act of March 19, 1918. Italian mathematician Quirico Filopanti introduced the idea of a worldwide system of time zones in his book Miranda! , published in 1858. He proposed 24 hourly time zones, which he called "longitudinal days",
726-480: A clock for each railroad, each showing a different time. Because of this a number of accidents occurred when trains from different companies using the same tracks mistimed their passings. Around 1863, Charles F. Dowd proposed a system of hourly standard time zones for North American railroads, 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 having north–south borders,
847-453: A code by itself. The term heliostat is sometimes used as a synonym for heliograph because of this origin. The Colomb shutter ( Bolton and Colomb , 1862) was originally invented to enable the transmission of morse code by signal lamp between Royal Navy ships at sea. The heliograph was heavily used by Nelson A. Miles in Arizona and New Mexico after he took over command (1886) of
968-444: A convenient time, usually at night, not exactly when they cross a certain longitude. Some ships simply remain on the time of the departing port during the whole trip. Ideal time zones, such as nautical time zones, are based on the mean solar time of a particular meridian in the middle of that zone with boundaries located 7.5 degrees east and west of the meridian. In practice, however, many time zone boundaries are drawn much farther to
1089-410: A distance and cablegram means something written via a cable, whereas telegraph implies the process of writing at a distance. Later, a Telex was a message sent by a Telex network, a switched network of teleprinters similar to a telephone network. A wirephoto or wire picture was a newspaper picture that was sent from a remote location by a facsimile telegraph . A diplomatic telegram, also known as
1210-470: A distance of a quarter of a mile. In the 1890s inventor Nikola Tesla worked on an air and ground conduction wireless electric power transmission system , similar to Loomis', which he planned to include wireless telegraphy. Tesla's experiments had led him to incorrectly conclude that he could use the entire globe of the Earth to conduct electrical energy and his 1901 large scale application of his ideas,
1331-473: A few days, sometimes taking all day to send a message despite the use of the highly sensitive mirror galvanometer developed by William Thomson (the future Lord Kelvin ) before being destroyed by applying too high a voltage. Its failure and slow speed of transmission prompted Thomson and Oliver Heaviside to find better mathematical descriptions of long transmission lines . The company finally succeeded in 1866 with an improved cable laid by SS Great Eastern ,
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#17327731160161452-555: A message was relayed 640 km (400 mi) in four hours. Miles' enemies used smoke signals and flashes of sunlight from metal, but lacked a sophisticated telegraph code. The heliograph was ideal for use in the American Southwest due to its clear air and mountainous terrain on which stations could be located. It was found necessary to lengthen the morse dash (which is much shorter in American Morse code than in
1573-493: A modification of surveying equipment ( Gauss , 1821). Various uses of mirrors were made for communication in the following years, mostly for military purposes, but the first device to become widely used was a heliograph with a moveable mirror ( Mance , 1869). The system was used by the French during the 1870–71 siege of Paris , with night-time signalling using kerosene lamps as the source of light. An improved version (Begbie, 1870)
1694-606: A natural rubber from the Palaquium gutta tree, after William Montgomerie sent samples to London from Singapore in 1843. The new material was tested by Michael Faraday and in 1845 Wheatstone suggested that it should be used on the cable planned between Dover and Calais by John Watkins Brett . The idea was proved viable when the South Eastern Railway company successfully tested a three-kilometre (two-mile) gutta-percha insulated cable with telegraph messages to
1815-614: A ship off the coast of Folkestone . The cable to France was laid in 1850 but was almost immediately severed by a French fishing vessel. It was relaid the next year and connections to Ireland and the Low Countries soon followed. Getting a cable across the Atlantic Ocean proved much more difficult. The Atlantic Telegraph Company , formed in London in 1856, had several failed attempts. A cable laid in 1858 worked poorly for
1936-440: A single-needle telegraph was adapted to indicate just two messages: "Line Clear" and "Line Blocked". The signaller would adjust his line-side signals accordingly. As first implemented in 1844 each station had as many needles as there were stations on the line, giving a complete picture of the traffic. As lines expanded, a sequence of pairs of single-needle instruments were adopted, one pair for each block in each direction. Wigwag
2057-744: A standard reference time while each location in England kept a different time. In the 19th century, as transportation and telecommunications improved, it became increasingly inconvenient for each location to observe its own solar time. In November 1840, the British Great Western Railway started using GMT kept by portable chronometers . This practice was soon followed by other railway companies in Great Britain and became known as railway time . Around August 23, 1852, time signals were first transmitted by telegraph from
2178-479: A standard time zone, but only some of them used an hourly offset from GMT. Many applied the time at a local astronomical observatory to an entire country, without any reference to GMT. It took many decades before all time zones were based on some standard offset from GMT or Coordinated Universal Time (UTC). By 1929, the majority of countries had adopted hourly time zones, though some countries such as Iran , India , Myanmar and parts of Australia had time zones with
2299-663: A substantial distance was by Ronalds in 1816 using an electrostatic generator . Ronalds offered his invention to the British Admiralty , but it was rejected as unnecessary, the existing optical telegraph connecting the Admiralty in London to their main fleet base in Portsmouth being deemed adequate for their purposes. As late as 1844, after the electrical telegraph had come into use, the Admiralty's optical telegraph
2420-418: A system for mass distributing information on current price of publicly listed companies. In a punched-tape system, the message is first typed onto punched tape using the code of the telegraph system—Morse code for instance. It is then, either immediately or at some later time, run through a transmission machine which sends the message to the telegraph network. Multiple messages can be sequentially recorded on
2541-503: A system of communication that would allow the central government to receive intelligence and to transmit orders in the shortest possible time. On 2 March 1791, at 11 am, they sent the message "si vous réussissez, vous serez bientôt couverts de gloire" (If you succeed, you will soon bask in glory) between Brulon and Parce, a distance of 16 kilometres (10 mi). The first means used a combination of black and white panels, clocks, telescopes, and codebooks to send their message. In 1792, Claude
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#17327731160162662-534: A telefax machine. In 1855, an Italian priest, Giovanni Caselli , also created an electric telegraph that could transmit images. Caselli called his invention " Pantelegraph ". Pantelegraph was successfully tested and approved for a telegraph line between Paris and Lyon . In 1881, English inventor Shelford Bidwell constructed the scanning phototelegraph that was the first telefax machine to scan any two-dimensional original, not requiring manual plotting or drawing. Around 1900, German physicist Arthur Korn invented
2783-466: A telegraph between St Petersburg and Kronstadt , but it was never completed. The first operative electric telegraph ( Gauss and Weber , 1833) connected Göttingen Observatory to the Institute of Physics about 1 km away during experimental investigations of the geomagnetic field. The first commercial telegraph was by Cooke and Wheatstone following their English patent of 10 June 1837. It
2904-461: A whole number of hours, but a few zones are offset by an additional 30 or 45 minutes, such as in India and Nepal . Some areas in a time zone may use a different offset for part of the year, typically one hour ahead during spring and summer , a practice known as daylight saving time (DST). In the table below, the locations that use daylight saving time (DST) are listed in their UTC offset when DST
3025-567: Is not in effect. When DST is in effect, approximately during spring and summer, their UTC offset is increased by one hour (except for Lord Howe Island , where it is increased by 30 minutes). For example, during the DST period California observes UTC−07:00 and the United Kingdom observes UTC+01:00 . The apparent position of the Sun in the sky, and thus solar time , varies by location due to
3146-407: Is 11 hours 30 minutes ahead of GMT. This standard was known as New Zealand Mean Time . Timekeeping on North American railroads in the 19th century was complex. Each railroad used its own standard time, usually based on the local time of its headquarters or most important terminus, and the railroad's train schedules were published using its own time. Some junctions served by several railroads had
3267-465: Is a form of flag signalling using a single flag. Unlike most forms of flag signalling, which are used over relatively short distances, wigwag is designed to maximise the distance covered—up to 32 km (20 mi) in some cases. Wigwag achieved this by using a large flag—a single flag can be held with both hands unlike flag semaphore which has a flag in each hand—and using motions rather than positions as its symbols since motions are more easily seen. It
3388-628: Is a standard established by the International Organization for Standardization defining methods of representing dates and times in textual form, including specifications for representing time zones. If a time is in Coordinated Universal Time (UTC), a "Z" is added directly after the time without a separating space. "Z" is the zone designator for the zero UTC offset. "09:30 UTC" is therefore represented as "09:30Z" or "0930Z". Likewise, "14:45:15 UTC"
3509-519: Is a telegraph consisting of a line of stations in towers or natural high points which signal to each other by means of shutters or paddles. Signalling by means of indicator pointers was called semaphore . Early proposals for an optical telegraph system were made to the Royal Society by Robert Hooke in 1684 and were first implemented on an experimental level by Sir Richard Lovell Edgeworth in 1767. The first successful optical telegraph network
3630-458: Is a telegraph machine that can send messages from a typewriter-like keyboard and print incoming messages in readable text with no need for the operators to be trained in the telegraph code used on the line. It developed from various earlier printing telegraphs and resulted in improved transmission speeds. The Morse telegraph (1837) was originally conceived as a system marking indentations on paper tape. A chemical telegraph making blue marks improved
3751-571: Is a telegraph system using reflected sunlight for signalling. It was mainly used in areas where the electrical telegraph had not been established and generally used the same code. The most extensive heliograph network established was in Arizona and New Mexico during the Apache Wars . The heliograph was standard military equipment as late as World War II . Wireless telegraphy developed in the early 20th century became important for maritime use, and
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3872-470: Is an area which observes a uniform standard time for legal , commercial and social purposes. Time zones tend to follow the boundaries between countries and their subdivisions instead of strictly following longitude , because it is convenient for areas in frequent communication to keep the same time. Each time zone is defined by a standard offset from Coordinated Universal Time (UTC). The offsets range from UTC−12:00 to UTC+14:00 , and are usually
3993-629: Is appended to local times in the same way that alphabetic time zone abbreviations (or "Z", as above) are appended. The offset from UTC changes with daylight saving time , e.g. a time offset in Chicago , which is in the North American Central Time Zone , is " −06:00 " for the winter (Central Standard Time) and " −05:00 " for the summer (Central Daylight Time). Time zones are often represented by alphabetic abbreviations such as "EST", "WST", and "CST", but these are not part of
4114-536: Is observed and clocks are advanced one hour. Chatham Daylight Time (CHADT) is 13 hours 45 minutes ahead of UTC, 45 minutes ahead of New Zealand Daylight Time (NZDT). Daylight saving time runs from the last Sunday in September at 2:45 to the first Sunday in April at 3:45. 43°53′54″S 176°31′44″W / 43.89833°S 176.52889°W / -43.89833; -176.52889 Time zone A time zone
4235-447: Is that it permits duplex communication. The Wheatstone tape reader was capable of a speed of 400 words per minute. A worldwide communication network meant that telegraph cables would have to be laid across oceans. On land cables could be run uninsulated suspended from poles. Underwater, a good insulator that was both flexible and capable of resisting the ingress of seawater was required. A solution presented itself with gutta-percha ,
4356-467: Is to allow the more efficient use of afternoon sunlight. Some of these locations also use daylight saving time (DST), further increasing the difference to local solar time. As a result, in summer, solar noon in the Spanish city of Vigo occurs at 14:41 clock time. This westernmost area of continental Spain never experiences sunset before 18:00 clock time, even in winter, despite lying 42 degrees north of
4477-599: Is updated whenever time zone or daylight saving time rules change. Oracle provides an updater tool for this purpose. As an alternative to the information bundled with the Java Platform, programmers may choose to use the Joda-Time library. This library includes its own data based on the IANA time zone database. As of Java 8 there is a new date and time API that can help with converting times. Traditionally, there
4598-403: Is usually converted to local time when displayed to the user, and times specified by the user in local time are converted to Unix time. The conversion takes into account the time zone and daylight saving time rules; by default the time zone and daylight saving time rules are set up when the system is configured, though individual processes can specify time zones and daylight saving time rules using
4719-533: Is written as "14:45:15Z" or "144515Z". UTC time is also known as "Zulu" time, since "Zulu" is a phonetic alphabet code word for the letter "Z". Offsets from UTC are written in the format ±hh:mm, ±hhmm, or ±hh (either hours ahead or behind UTC). For example, if the time being described is one hour ahead of UTC (such as the time in Germany during the winter), the zone designator would be " +01:00 ", "+0100", or simply "+01". This numeric representation of time zones
4840-645: The Bildtelegraph widespread in continental Europe especially since a widely noticed transmission of a wanted-person photograph from Paris to London in 1908 used until the wider distribution of the radiofax. Its main competitors were the Bélinographe by Édouard Belin first, then since the 1930s, the Hellschreiber , invented in 1929 by German inventor Rudolf Hell , a pioneer in mechanical image scanning and transmission. The late 1880s through to
4961-660: The English Channel (1899), from shore to ship (1899) and finally across the Atlantic (1901). A study of these demonstrations of radio, with scientists trying to work out how a phenomenon predicted to have a short range could transmit "over the horizon", led to the discovery of a radio reflecting layer in the Earth's atmosphere in 1902, later called the ionosphere . Radiotelegraphy proved effective for rescue work in sea disasters by enabling effective communication between ships and from ship to shore. In 1904, Marconi began
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5082-508: The First Macedonian War . Nothing else that could be described as a true telegraph existed until the 17th century. Possibly the first alphabetic telegraph code in the modern era is due to Franz Kessler who published his work in 1616. Kessler used a lamp placed inside a barrel with a moveable shutter operated by the signaller. The signals were observed at a distance with the newly invented telescope. An optical telegraph
5203-589: The Han dynasty (200 BC – 220 AD) signallers had a choice of lights, flags, or gunshots to send signals. By the Tang dynasty (618–907) a message could be sent 1,100 kilometres (700 mi) in 24 hours. The Ming dynasty (1368–1644) added artillery to the possible signals. While the signalling was complex (for instance, different-coloured flags could be used to indicate enemy strength), only predetermined messages could be sent. The Chinese signalling system extended well beyond
5324-544: The IANA time zone database and includes the ability to get, set and convert between time zones. The DateTime objects and related functions have been compiled into the PHP core since 5.2. This includes the ability to get and set the default script time zone, and DateTime is aware of its own time zone internally. PHP.net provides extensive documentation on this. As noted there, the most current time zone database can be implemented via
5445-532: The London and Birmingham Railway line's chief engineer. The messages were for the operation of the rope-haulage system for pulling trains up the 1 in 77 bank. The world's first permanent railway telegraph was completed in July 1839 between London Paddington and West Drayton on the Great Western Railway with an electric telegraph using a four-needle system. The concept of a signalling "block" system
5566-723: The PECL timezonedb. Telegraph Telegraphy is the long-distance transmission of messages where the sender uses symbolic codes, known to the recipient, rather than a physical exchange of an object bearing the message. Thus flag semaphore is a method of telegraphy, whereas pigeon post is not. Ancient signalling systems, although sometimes quite extensive and sophisticated as in China, were generally not capable of transmitting arbitrary text messages. Possible messages were fixed and predetermined, so such systems are thus not true telegraphs. The earliest true telegraph put into widespread use
5687-513: The TZ environment variable . This allows users in multiple time zones, or in the same time zone but with different daylight saving time rules, to use the same computer, with their respective local times displayed correctly to each user. Time zone and daylight saving time rule information most commonly comes from the IANA time zone database . In fact, many systems, including anything using the GNU C Library ,
5808-416: The high seas . As an ideal form of the terrestrial time zone system, nautical time zones consist of gores of 15° offset from GMT by a whole number of hours. A nautical date line follows the 180th meridian, bisecting one 15° gore into two 7.5° gores that differ from GMT by ±12 hours. However, in practice each ship may choose what time to observe at each location. Ships may decide to adjust their clocks at
5929-520: The spherical shape of the Earth. This variation corresponds to four minutes of time for every degree of longitude , so for example when it is solar noon in London , it is about 10 minutes before solar noon in Bristol , which is about 2.5 degrees to the west. The Royal Observatory, Greenwich , founded in 1675, established Greenwich Mean Time (GMT), the mean solar time at that location, as an aid to mariners to determine longitude at sea, providing
6050-471: The 1850s until well into the 20th century, British submarine cable systems dominated the world system. This was set out as a formal strategic goal, which became known as the All Red Line . In 1896, there were thirty cable-laying ships in the world and twenty-four of them were owned by British companies. In 1892, British companies owned and operated two-thirds of the world's cables and by 1923, their share
6171-530: The 1890s saw the discovery and then development of a newly understood phenomenon into a form of wireless telegraphy , called Hertzian wave wireless telegraphy, radiotelegraphy, or (later) simply " radio ". Between 1886 and 1888, Heinrich Rudolf Hertz published the results of his experiments where he was able to transmit electromagnetic waves (radio waves) through the air, proving James Clerk Maxwell 's 1873 theory of electromagnetic radiation . Many scientists and inventors experimented with this new phenomenon but
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#17327731160166292-534: The British government followed—by March 1897, Marconi had transmitted Morse code signals over a distance of about 6 km ( 3 + 1 ⁄ 2 mi) across Salisbury Plain . On 13 May 1897, Marconi, assisted by George Kemp, a Cardiff Post Office engineer, transmitted the first wireless signals over water to Lavernock (near Penarth in Wales) from Flat Holm . His star rising, he was soon sending signals across
6413-645: The Great Wall. Signal towers away from the wall were used to give early warning of an attack. Others were built even further out as part of the protection of trade routes, especially the Silk Road . Signal fires were widely used in Europe and elsewhere for military purposes. The Roman army made frequent use of them, as did their enemies, and the remains of some of the stations still exist. Few details have been recorded of European/Mediterranean signalling systems and
6534-466: The Morse system connected Baltimore to Washington , and by 1861 the west coast of the continent was connected to the east coast. The Cooke and Wheatstone telegraph , in a series of improvements, also ended up with a one-wire system, but still using their own code and needle displays . The electric telegraph quickly became a means of more general communication. The Morse system was officially adopted as
6655-578: The Royal Observatory. By 1855, 98% of Great Britain's public clocks were using GMT, but it was not made the island's legal time until August 2, 1880. Some British clocks from this period have two minute hands, one for the local time and one for GMT. On November 2, 1868, the British Colony of New Zealand officially adopted a standard time to be observed throughout the colony. It was based on longitude 172°30′ east of Greenwich , that
6776-595: The Terminal Server so that users see the correct time for their time zone in their desktop/application sessions. Terminal Services uses the server base time on the Terminal Server and the client time zone information to calculate the time in the session. While most application software will use the underlying operating system for time zone and daylight saving time rule information, the Java Platform , from version 1.3.1, has maintained its own database of time zone and daylight saving time rule information. This database
6897-534: The US version shows Eastern Time . US Eastern Time and Pacific Time are also used fairly commonly on many US-based English-language websites with global readership. The format is typically based in the W3C Note "datetime". Email systems and other messaging systems ( IRC chat , etc.) time-stamp messages using UTC, or else include the sender's time zone as part of the message, allowing the receiving program to display
7018-506: The area becomes a function of UTC time. The time differences may also result in different dates. For example, when it is 22:00 on Monday in Egypt (UTC+02:00), it is 01:00 on Tuesday in Pakistan (UTC+05:00). The table "Time of day by zone" gives an overview on the time relations between different zones. Since the 1920s, a nautical standard time system has been in operation for ships on
7139-513: The article on daylight saving time for more details on this aspect.) Web servers presenting web pages primarily for an audience in a single time zone or a limited range of time zones typically show times as a local time, perhaps with UTC time in brackets. More internationally oriented websites may show times in UTC only or using an arbitrary time zone. For example, the international English-language version of CNN includes GMT and Hong Kong Time, whereas
7260-469: The begin and end dates of daylight saving time are changed, calendar entries should stay the same in local time, even though they may shift in UTC time. Unix-like systems, including Linux and macOS , keep system time in Unix time format, representing the number of seconds (excluding leap seconds ) that have elapsed since 00:00:00 Coordinated Universal Time (UTC) on Thursday, January 1, 1970. Unix time
7381-549: The calendar events are assumed to take place in the time zone the computer or smartphone was on when creating the event. The event can be shown at the wrong time. For example, if a New Yorker plans to meet someone in Los Angeles at 9 am, and makes a calendar entry at 9 am (which the computer assumes is New York time), the calendar entry will be at 6 am if taking the computer's time zone. Calendaring software must also deal with daylight saving time (DST). If, for political reasons,
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#17327731160167502-438: The consensus was that these new waves (similar to light) would be just as short range as light, and, therefore, useless for long range communication. At the end of 1894, the young Italian inventor Guglielmo Marconi began working on the idea of building a commercial wireless telegraphy system based on the use of Hertzian waves (radio waves), a line of inquiry that he noted other inventors did not seem to be pursuing. Building on
7623-411: The coordinates of the letter of the alphabet being transmitted. The number of said torches held up signalled the grid square that contained the letter. There is no definite record of the system ever being used, but there are several passages in ancient texts that some think are suggestive. Holzmann and Pehrson, for instance, suggest that Livy is describing its use by Philip V of Macedon in 207 BC during
7744-458: The earliest electrical telegraphs. A telegraph message sent by an electrical telegraph operator or telegrapher using Morse code (or a printing telegraph operator using plain text) was known as a telegram. A cablegram was a message sent by a submarine telegraph cable, often shortened to "cable" or "wire". The suffix -gram is derived from ancient Greek: γραμμα ( gramma ), meaning something written, i.e. telegram means something written at
7865-564: The equation is equivalent to UTC. The conversion equation can be rearranged to For example, the New York Stock Exchange opens at 09:30 ( EST , UTC offset= −05:00). In California ( PST , UTC offset= −08:00) and India ( IST , UTC offset= +05:30), the New York Stock Exchange opens at These calculations become more complicated near the time switch to or from daylight saving time, as the UTC offset for
7986-532: The equator. Near the summer solstice , Vigo has sunset times after 22:00, similar to those of Stockholm , which is in the same time zone and 17 degrees farther north. Stockholm has much earlier sunrises, though. In the United States, the reasons were more historical and business-related. In Midwestern states, like Indiana and Michigan , those living in Indianapolis and Detroit wanted to be on
8107-537: The erroneous belief that there was an electrified atmospheric stratum accessible at low altitude. They thought atmosphere current, connected with a return path using "Earth currents" would allow for wireless telegraphy as well as supply power for the telegraph, doing away with artificial batteries. A more practical demonstration of wireless transmission via conduction came in Amos Dolbear 's 1879 magneto electric telephone that used ground conduction to transmit over
8228-415: The extensive definition used by Chappe, Morse argued that the term telegraph can strictly be applied only to systems that transmit and record messages at a distance. This is to be distinguished from semaphore , which merely transmits messages. Smoke signals, for instance, are to be considered semaphore, not telegraph. According to Morse, telegraph dates only from 1832 when Pavel Schilling invented one of
8349-535: The extent of their territory far exceeds the ideal 15° of longitude for one hour; other countries, such as Spain and Argentina , use standard hour-based offsets, but not necessarily those that would be determined by their geographical location. The consequences, in some areas, can affect the lives of local citizens, and in extreme cases contribute to larger political issues, such as in the western reaches of China. In Russia, which has 11 time zones , two time zones were removed in 2010 and reinstated in 2014. ISO 8601
8470-460: The fight against Geronimo and other Apache bands in the Apache Wars . Miles had previously set up the first heliograph line in the US between Fort Keogh and Fort Custer in Montana . He used the heliograph to fill in vast, thinly populated areas that were not covered by the electric telegraph. Twenty-six stations covered an area 320 by 480 km (200 by 300 mi). In a test of the system,
8591-573: The first centered on Washington, D.C. , but by 1872 the first was centered on meridian 75° west of Greenwich , with natural borders such as sections of the Appalachian Mountains . Dowd's system was never accepted by North American railroads. Chief meteorologist at the United States Weather Bureau Cleveland Abbe divided the United States into four standard time zones for consistency among
8712-532: The first centred on the meridian of Rome . He also proposed a universal time to be used in astronomy and telegraphy. However, his book attracted no attention until long after his death. Scottish -born Canadian Sir Sandford Fleming proposed a worldwide system of time zones in 1876 - see Sandford Fleming § Inventor of worldwide standard time . The proposal divided the world into twenty-four time zones labeled A-Y (skipping J), each one covering 15 degrees of longitude. All clocks within each zone would be set to
8833-623: The first commercial service to transmit nightly news summaries to subscribing ships, which could incorporate them into their on-board newspapers. A regular transatlantic radio-telegraph service was finally begun on 17 October 1907. Notably, Marconi's apparatus was used to help rescue efforts after the sinking of RMS Titanic . Britain's postmaster-general summed up, referring to the Titanic disaster, "Those who have been saved, have been saved through one man, Mr. Marconi...and his marvellous invention." The successful development of radiotelegraphy
8954-449: The greatest terrestrial time zone difference on Earth, with a 3.5 hour difference between Afghanistan's UTC+4:30 and China's UTC+08:00 . Many countries, and sometimes just certain regions of countries, adopt daylight saving time (DST), also known as summer time, during part of the year. This typically involves advancing clocks by an hour near the start of spring and adjusting back in autumn ("spring forward", "fall back"). Modern DST
9075-535: The ground without any wires connecting the stations. Other attempts were made to send the electric current through bodies of water, to span rivers, for example. Prominent experimenters along these lines included Samuel F. B. Morse in the United States and James Bowman Lindsay in Great Britain, who in August 1854, was able to demonstrate transmission across a mill dam at a distance of 500 yards (457 metres). US inventors William Henry Ward (1871) and Mahlon Loomis (1872) developed electrical conduction systems based on
9196-419: The ideas of previous scientists and inventors Marconi re-engineered their apparatus by trial and error attempting to build a radio-based wireless telegraphic system that would function the same as wired telegraphy. He would work on the system through 1895 in his lab and then in field tests making improvements to extend its range. After many breakthroughs, including applying the wired telegraphy concept of grounding
9317-416: The international time and date standard ISO 8601 . Such designations can be ambiguous; for example, "CST" can mean (North American) Central Standard Time (UTC−06:00), Cuba Standard Time (UTC−05:00) and China Standard Time (UTC+08:00), and it is also a widely used variant of ACST ( Australian Central Standard Time , UTC+09:30). Conversion between time zones obeys the relationship in which each side of
9438-561: The largest ship of its day, designed by Isambard Kingdom Brunel . An overland telegraph from Britain to India was first connected in 1866 but was unreliable so a submarine telegraph cable was connected in 1870. Several telegraph companies were combined to form the Eastern Telegraph Company in 1872. Australia was first linked to the rest of the world in October 1872 by a submarine telegraph cable at Darwin . From
9559-415: The letter post on price, and competition from the telephone , which removed their speed advantage, drove the telegraph into decline from 1920 onwards. The few remaining telegraph applications were largely taken over by alternatives on the internet towards the end of the 20th century. The word telegraph (from Ancient Greek : τῆλε ( têle ) 'at a distance' and γράφειν ( gráphein ) 'to write')
9680-421: The line at his own expense and agreed that the railway could have free use of it in exchange for the right to open it up to the public. Most of the early electrical systems required multiple wires (Ronalds' system was an exception), but the system developed in the United States by Morse and Vail was a single-wire system. This was the system that first used the soon-to-become-ubiquitous Morse code . By 1844,
9801-653: The message's date and time of sending in the recipient's local time. Database records that include a time stamp typically use UTC, especially when the database is part of a system that spans multiple time zones. The use of local time for time-stamping records is not recommended for time zones that implement daylight saving time because once a year there is a one-hour period when local times are ambiguous. Calendar systems nowadays usually tie their time stamps to UTC, and show them differently on computers that are in different time zones. That works when having telephone or internet meetings. It works less well when travelling, because
9922-624: The modern International Morse code) to aid differentiating from the morse dot. Use of the heliograph declined from 1915 onwards, but remained in service in Britain and British Commonwealth countries for some time. Australian forces used the heliograph as late as 1942 in the Western Desert Campaign of World War II . Some form of heliograph was used by the mujahideen in the Soviet–Afghan War (1979–1989). A teleprinter
10043-416: The necessary support for working with all (or almost all) possible local times based on the various time zones. Internally, operating systems typically use UTC as their basic time-keeping standard , while providing services for converting local times to and from UTC, and also the ability to automatically change local time conversions at the start and end of daylight saving time in the various time zones. (See
10164-399: The possible messages. One of the few for which details are known is a system invented by Aeneas Tacticus (4th century BC). Tacticus's system had water filled pots at the two signal stations which were drained in synchronisation. Annotation on a floating scale indicated which message was being sent or received. Signals sent by means of torches indicated when to start and stop draining to keep
10285-493: The same meridian but north of the Arctic Circle, has two sunsets on the same day in early August, one shortly after midnight at the start of the day, and the other shortly before midnight at the end of the day. China extends as far west as 73°E , but all parts of it use UTC+08:00 ( 120°E ), so solar "noon" can occur as late as 15:00 in western portions of China such as Xinjiang . The Afghanistan-China border marks
10406-419: The same run of tape. The advantage of doing this is that messages can be sent at a steady, fast rate making maximum use of the available telegraph lines. The economic advantage of doing this is greatest on long, busy routes where the cost of the extra step of preparing the tape is outweighed by the cost of providing more telegraph lines. The first machine to use punched tape was Bain's teleprinter (Bain, 1843), but
10527-548: The same time as the others, but differed by one hour from those in the neighboring zones. He advocated his system at several international conferences, including the International Meridian Conference , where it received some consideration. The system has not been directly adopted, but some maps divide the world into 24 time zones and assign letters to them, similarly to Fleming's system. By about 1900, almost all inhabited places on Earth had adopted
10648-419: The same time zone as New York to simplify communications and transactions. A more extreme example is Nome, Alaska , which is at 165°24′W longitude – just west of center of the idealized Samoa Time Zone ( 165°W ). Nevertheless, Nome observes Alaska Time ( 135°W ) with DST so it is slightly more than two hours ahead of the sun in winter and over three in summer. Kotzebue, Alaska , also near
10769-455: The speed of recording ( Bain , 1846), but was delayed by a patent challenge from Morse. The first true printing telegraph (that is printing in plain text) used a spinning wheel of types in the manner of a daisy wheel printer ( House , 1846, improved by Hughes , 1855). The system was adopted by Western Union . Early teleprinters used the Baudot code , a five-bit sequential binary code. This
10890-579: The standard for continental European telegraphy in 1851 with a revised code, which later became the basis of International Morse Code . However, Great Britain and the British Empire continued to use the Cooke and Wheatstone system, in some places as late as the 1930s. Likewise, the United States continued to use American Morse code internally, requiring translation operators skilled in both codes for international messages. Railway signal telegraphy
11011-462: The synchronisation. None of the signalling systems discussed above are true telegraphs in the sense of a system that can transmit arbitrary messages over arbitrary distances. Lines of signalling relay stations can send messages to any required distance, but all these systems are limited to one extent or another in the range of messages that they can send. A system like flag semaphore , with an alphabetic code, can certainly send any given message, but
11132-559: The system is designed for short-range communication between two persons. An engine order telegraph , used to send instructions from the bridge of a ship to the engine room, fails to meet both criteria; it has a limited distance and very simple message set. There was only one ancient signalling system described that does meet these criteria. That was a system using the Polybius square to encode an alphabet. Polybius (2nd century BC) suggested using two successive groups of torches to identify
11253-619: The system saw only limited use. Later versions of Bain's system achieved speeds up to 1000 words per minute, far faster than a human operator could achieve. The first widely used system (Wheatstone, 1858) was first put into service with the British General Post Office in 1867. A novel feature of the Wheatstone system was the use of bipolar encoding . That is, both positive and negative polarity voltages were used. Bipolar encoding has several advantages, one of which
11374-465: The system time to be fetched as a count of 100 ns units since 1601-01-01 00:00:00 UTC. The system registry contains time zone information that includes the offset from UTC and rules that indicate the start and end dates for daylight saving in each zone. Interaction with the user normally uses local time, and application software is able to calculate the time in various zones. Terminal Servers allow remote computers to redirect their time zone settings to
11495-527: The time-zone system. It was 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, often in major cities. For example, the border between its Eastern and Central time zones ran through Detroit , Buffalo , Pittsburgh , Atlanta , and Charleston . It was inaugurated on Sunday, November 18, 1883, also called "The Day of Two Noons", when each railroad station clock
11616-537: The transmitter and receiver, Marconi was able, by early 1896, to transmit radio far beyond the short ranges that had been predicted. Having failed to interest the Italian government, the 22-year-old inventor brought his telegraphy system to Britain in 1896 and met William Preece , a Welshman, who was a major figure in the field and Chief Engineer of the General Post Office . A series of demonstrations for
11737-445: The two stations to form a complete electrical circuit or "loop". In 1837, however, Carl August von Steinheil of Munich , Germany , found that by connecting one leg of the apparatus at each station to metal plates buried in the ground, he could eliminate one wire and use a single wire for telegraphic communication. This led to speculation that it might be possible to eliminate both wires and therefore transmit telegraph signals through
11858-471: The war. Similarly, prior to World War II, the Netherlands observed "Amsterdam Time", which was twenty minutes ahead of Greenwich Mean Time. They were obliged to follow German time during the war, and kept it thereafter. In the mid-1970s the Netherlands, as other European states, began observing daylight saving (summer) time. One reason to draw time zone boundaries far to the west of their ideal meridians
11979-472: The weather stations. In 1879, he published a paper titled Report on Standard Time . In 1883, he convinced North American railroad companies to adopt his time-zone system. In 1884, Britain, which had already adopted its own standard time system for England, Scotland, and Wales, helped gather international consent for global time. In time, the American government, influenced in part by Abbe's 1879 paper, adopted
12100-576: The west, and some countries are located entirely outside their ideal time zones. For example, even though the Prime Meridian (0°) passes through Spain and France , they use the mean solar time of 15 degrees east ( Central European Time ) rather than 0 degrees (Greenwich Mean Time). France previously used GMT, but was switched to CET (Central European Time) during the German occupation of the country during World War II and did not switch back after
12221-459: Was a competitor to electrical telegraphy using submarine telegraph cables in international communications. Telegrams became a popular means of sending messages once telegraph prices had fallen sufficiently. Traffic became high enough to spur the development of automated systems— teleprinters and punched tape transmission. These systems led to new telegraph codes , starting with the Baudot code . However, telegrams were never able to compete with
12342-485: Was a telegraph code developed for use on the French telegraph using a five-key keyboard ( Baudot , 1874). Teleprinters generated the same code from a full alphanumeric keyboard. A feature of the Baudot code, and subsequent telegraph codes, was that, unlike Morse code, every character has a code of the same length making it more machine friendly. The Baudot code was used on the earliest ticker tape machines ( Calahan , 1867),
12463-474: Was appointed Ingénieur-Télégraphiste and charged with establishing a line of stations between Paris and Lille , a distance of 230 kilometres (140 mi). It was used to carry dispatches for the war between France and Austria. In 1794, it brought news of a French capture of Condé-sur-l'Escaut from the Austrians less than an hour after it occurred. A decision to replace the system with an electric telegraph
12584-401: Was coined by the French inventor of the semaphore telegraph , Claude Chappe , who also coined the word semaphore . A telegraph is a device for transmitting and receiving messages over long distances, i.e., for telegraphy. The word telegraph alone generally refers to an electrical telegraph . Wireless telegraphy is transmission of messages over radio with telegraphic codes. Contrary to
12705-414: Was demonstrated on the London and Birmingham Railway in July of the same year. In July 1839, a five-needle, five-wire system was installed to provide signalling over a record distance of 21 km on a section of the Great Western Railway between London Paddington station and West Drayton. However, in trying to get railway companies to take up his telegraph more widely for railway signalling , Cooke
12826-421: Was developed in Britain from the 1840s onward. It was used to manage railway traffic and to prevent accidents as part of the railway signalling system. On 12 June 1837 Cooke and Wheatstone were awarded a patent for an electric telegraph. This was demonstrated between Euston railway station —where Wheatstone was located—and the engine house at Camden Town—where Cooke was stationed, together with Robert Stephenson ,
12947-415: Was first proposed in 1907 and was in widespread use in 1916 as a wartime measure aimed at conserving coal . Despite controversy , many countries have used it off and on since then; details vary by location and change occasionally. Countries around the equator usually do not observe daylight saving time, since the seasonal difference in sunlight there is minimal. Many computer operating systems include
13068-658: Was invented by Claude Chappe and operated in France from 1793. The two most extensive systems were Chappe's in France, with branches into neighbouring countries, and the system of Abraham Niclas Edelcrantz in Sweden. During 1790–1795, at the height of the French Revolution , France needed a swift and reliable communication system to thwart the war efforts of its enemies. In 1790, the Chappe brothers set about devising
13189-536: Was invented by US Army surgeon Albert J. Myer in the 1850s who later became the first head of the Signal Corps . Wigwag was used extensively during the American Civil War where it filled a gap left by the electrical telegraph. Although the electrical telegraph had been in use for more than a decade, the network did not yet reach everywhere and portable, ruggedized equipment suitable for military use
13310-782: Was made in 1846, but it took a decade before it was fully taken out of service. The fall of Sevastopol was reported by Chappe telegraph in 1855. The Prussian system was put into effect in the 1830s. However, they were highly dependent on good weather and daylight to work and even then could accommodate only about two words per minute. The last commercial semaphore link ceased operation in Sweden in 1880. As of 1895, France still operated coastal commercial semaphore telegraph stations, for ship-to-shore communication. The early ideas for an electric telegraph included in 1753 using electrostatic deflections of pith balls, proposals for electrochemical bubbles in acid by Campillo in 1804 and von Sömmering in 1809. The first experimental system over
13431-400: Was not immediately available. Permanent or semi-permanent stations were established during the war, some of them towers of enormous height and the system was extensive enough to be described as a communications network. A heliograph is a telegraph that transmits messages by flashing sunlight with a mirror, usually using Morse code. The idea for a telegraph of this type was first proposed as
13552-455: Was preceded by a 50-year history of ingenious but ultimately unsuccessful experiments by inventors to achieve wireless telegraphy by other means. Several wireless electrical signaling schemes based on the (sometimes erroneous) idea that electric currents could be conducted long-range through water, ground, and air were investigated for telegraphy before practical radio systems became available. The original telegraph lines used two wires between
13673-433: Was proposed by Cooke in 1842. Railway signal telegraphy did not change in essence from Cooke's initial concept for more than a century. In this system each line of railway was divided into sections or blocks of varying length. Entry to and exit from the block was to be authorised by electric telegraph and signalled by the line-side semaphore signals, so that only a single train could occupy the rails. In Cooke's original system,
13794-501: Was quickly followed by a different system developed in the United States by Samuel Morse . The electric telegraph was slower to develop in France due to the established optical telegraph system, but an electrical telegraph was put into use with a code compatible with the Chappe optical telegraph. The Morse system was adopted as the international standard in 1865, using a modified Morse code developed in Germany in 1848. The heliograph
13915-549: Was rejected several times in favour of the more familiar, but shorter range, steam-powered pneumatic signalling. Even when his telegraph was taken up, it was considered experimental and the company backed out of a plan to finance extending the telegraph line out to Slough . However, this led to a breakthrough for the electric telegraph, as up to this point the Great Western had insisted on exclusive use and refused Cooke permission to open public telegraph offices. Cooke extended
14036-502: Was reset as standard-time noon was reached within each time zone. The North American zones were named Intercolonial, Eastern, Central, Mountain, 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 (located about halfway between the meridians of Eastern and Central time), which kept local time until 1900, then tried Central Standard Time, local mean time , and Eastern Standard Time (EST) before
14157-496: Was still 42.7 percent. During World War I , Britain's telegraph communications were almost completely uninterrupted while it was able to quickly cut Germany's cables worldwide. In 1843, Scottish inventor Alexander Bain invented a device that could be considered the first facsimile machine . He called his invention a "recording telegraph". Bain's telegraph was able to transmit images by electrical wires. Frederick Bakewell made several improvements on Bain's design and demonstrated
14278-404: Was still used, although it was accepted that poor weather ruled it out on many days of the year. France had an extensive optical telegraph system dating from Napoleonic times and was even slower to take up electrical systems. Eventually, electrostatic telegraphs were abandoned in favour of electromagnetic systems. An early experimental system ( Schilling , 1832) led to a proposal to establish
14399-617: Was the Chappe telegraph , an optical telegraph invented by Claude Chappe in the late 18th century. The system was used extensively in France, and European nations occupied by France, during the Napoleonic era . The electric telegraph started to replace the optical telegraph in the mid-19th century. It was first taken up in Britain in the form of the Cooke and Wheatstone telegraph , initially used mostly as an aid to railway signalling . This
14520-480: Was used by British military in many colonial wars, including the Anglo-Zulu War (1879). At some point, a morse key was added to the apparatus to give the operator the same degree of control as in the electric telegraph. Another type of heliograph was the heliostat or heliotrope fitted with a Colomb shutter. The heliostat was essentially a surveying instrument with a fixed mirror and so could not transmit
14641-669: Was very little in the way of time zone support for JavaScript . Essentially the programmer had to extract the UTC offset by instantiating a time object, getting a GMT time from it, and differencing the two. This does not provide a solution for more complex daylight saving variations, such as divergent DST directions between northern and southern hemispheres. ECMA-402, the standard on Internationalization API for JavaScript, provides ways of formatting Time Zones. However, due to size constraint, some implementations or distributions do not include it. The DateTime object in Perl supports all entries in
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