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Master Clock
A master clock is a precision clock that provides timing signals to synchronise slave clocks as part of a clock network. Networks of electric clocks connected by wires to a precision master pendulum clock began to be used in institutions like factories, offices, and schools around 1900. Modern radio clocks are synchronised by radio signals or Internet connections to a worldwide time system called Coordinated Universal Time (UTC), which is governed by primary reference atomic clocks in many countries. A modern, atomic version of a master clock is the large clock ensemble found at the U.S. Naval Observatory. History Between the late 1800s and the availability of Internet time services, many large institutions that depended on accurate timekeeping such as schools, offices, railway networks, telephone exchanges, and factories used master/slave clock networks. These consisted of multiple slave clocks and other timing devices, connected through wires to a master clock whic ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
Master Clock Driving Slave Clocks
Master, master's or masters may refer to: Ranks or titles In education: *Master (college), head of a college *Master's degree, a postgraduate or sometimes undergraduate degree in the specified discipline *Schoolmaster or master, presiding officer of a school In military: *Master (naval), a former naval rank *Master mariner, a licensed mariner who is qualified to be a sea captain in the merchant marine *Master or shipmaster, the sea captain of a merchant vessel * Master-at-arms, a naval police officer, often addressed as "Master" in the Royal Navy In orders and organizations: *Master craftsman, in the Medieval guilds In other: *Master (form of address), an English honorific for boys and young men *Master (judiciary), a judicial official in the courts of common law jurisdictions *Master (Peerage of Scotland), the male heir-apparent or heir-presumptive to a title in the Peerage of Scotland * Master of ceremonies, or MC (emcee), the host of an official public or private staged even ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
Time Card
Time is the continuous progression of existence that occurs in an apparently irreversible succession from the past, through the present, and into the future. It is a component quantity of various measurements used to sequence events, to compare the duration of events (or the intervals between them), and to quantify rates of change of quantities in material reality or in the conscious experience. Time is often referred to as a fourth dimension, along with three spatial dimensions. Time is one of the seven fundamental physical quantities in both the International System of Units (SI) and International System of Quantities. The SI base unit of time is the second, which is defined by measuring the electronic transition frequency of caesium atoms. General relativity is the primary framework for understanding how spacetime works. Through advances in both theoretical and experimental investigations of spacetime, it has been shown that time can be distorted and dilated, particular ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
Escapement
An escapement is a mechanical linkage in mechanical watches and clocks that gives impulses to the timekeeping element and periodically releases the gear train to move forward, advancing the clock's hands. The impulse action transfers energy to the clock's timekeeping element (usually a pendulum or balance wheel) to replace the energy lost to friction during its cycle and keep the timekeeper oscillating. The escapement is driven by force from a coiled spring (device), spring or a suspended weight, transmitted through the timepiece's gear train. Each swing of the pendulum or balance wheel releases a tooth of the escapement's ''escape wheel'', allowing the clock's gear train to advance or "escape" by a fixed amount. This regular periodic advancement moves the clock's hands forward at a steady rate. At the same time, the tooth gives the timekeeping element a push, before another tooth catches on the escapement's pallet, returning the escapement to its "locked" state. The sudden stoppi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
Pendulum Clock
A pendulum clock is a clock that uses a pendulum, a swinging weight, as its timekeeping element. The advantage of a pendulum for timekeeping is that it is an approximate harmonic oscillator: It swings back and forth in a precise time interval dependent on its length, and resists swinging at other rates. From its invention in 1656 by Christiaan Huygens, inspired by Galileo Galilei, until the 1930s, the pendulum clock was the world's most precise timekeeper, accounting for its widespread use. Throughout the 18th and 19th centuries, pendulum clocks in homes, factories, offices, and railroad stations served as primary time standards for scheduling daily life, work shifts, and public transportation. Their greater accuracy allowed for the faster pace of life which was necessary for the Industrial Revolution. The home pendulum clock was replaced by less-expensive synchronous electric clocks in the 1930s and 1940s. Pendulum clocks are now kept mostly for their Interior decor, decorative ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
Shortt–Synchronome Clock
The Shortt–Synchronome free pendulum clock is a complex precision electromechanical pendulum clock invented in 1921 by British railway engineer William Hamilton Shortt in collaboration with horologist Frank Hope-Jones, and manufactured by the Synchronome Company, Ltd., of London. They were the most accurate pendulum clocks ever commercially produced, and became the highest standard for timekeeping between the 1920s and the 1940s, after which mechanical clocks were superseded by Quartz clock, quartz time standards. They were used worldwide in Astronomical observatory, astronomical observatories, Naval observatory, naval observatories, in scientific research, and as a primary standard for national Time signal, time dissemination services. The Shortt was the first clock to be a more accurate timekeeper than the Earth itself; it was used in 1926 to detect tiny seasonal changes in the Earth's rotation rate. Shortt clocks achieved accuracy of around a second per year, although #Rece ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
Electric Clock
An electric clock is a clock that is powered by electricity, as opposed to a mechanical clock which is powered by a hanging weight or a mainspring. The term is often applied to the electrically powered mechanical clocks that were used before quartz clocks were introduced in the 1980s. The first experimental electric clocks were constructed around the 1840s, but they were not widely manufactured until mains electric power became available in the 1890s. In the 1930s, the synchronous electric clock replaced mechanical clocks as the most widely used type of clock. Types Electric clocks can operate by several different types of mechanism: ;Electromechanical clocks: These have a traditional mechanical movement (clockwork), movement, which keeps time with an oscillating pendulum or balance wheel powered through a gear train by a mainspring, but use electricity to rewind the mainspring with an electric motor or electromagnet. This mechanism is found mostly in antique clocks. ;Electric ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
General Post Office
The General Post Office (GPO) was the state postal system and telecommunications carrier of the United Kingdom until 1969. Established in England in the 17th century, the GPO was a state monopoly covering the dispatch of items from a specific sender to a specific receiver (which was to be of great importance when new forms of communication were invented); it was overseen by a Government minister, the Postmaster General. Over time its remit was extended to Scotland and Ireland, and across parts of the British Empire. The GPO was abolished by the Post Office Act 1969, which transferred its assets to the Post Office, so changing it from a Department of State to a statutory corporation. Responsibility for telecommunications was given to Post Office Telecommunications, the successor of the GPO Telegraph and Telephones department. In 1980, the telecommunications and postal sides were split prior to British Telecommunications' conversion into a totally separate publicly owned c ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
Greenwich Observatory
The Royal Observatory, Greenwich (ROG; known as the Old Royal Observatory from 1957 to 1998, when the working Royal Greenwich Observatory, RGO, temporarily moved south from Greenwich to Herstmonceux) is an observatory situated on a hill in Greenwich Park in south east London, overlooking the River Thames to the north. It played a major role in the history of astronomy and navigation, and because the Prime Meridian passed through it, it gave its name to Greenwich Mean Time, the precursor to today's Coordinated Universal Time (UTC). The ROG has the IAU observatory code of 000, the first in the list. ROG, the National Maritime Museum, the Queen's House and the clipper ship '' Cutty Sark'' are collectively designated Royal Museums Greenwich. The observatory was commissioned in 1675 by King Charles II, with the foundation stone being laid on 10 August. The old hilltop site of Greenwich Castle was chosen by Sir Christopher Wren, a former Savilian Professor of Astronomy; a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
Naval Observatory
The United States Naval Observatory (USNO) is a scientific and military facility that produces geopositioning, navigation and timekeeping data for the United States Navy and the United States Department of Defense. Established in 1830 as the Depot of Charts and Instruments, it is one of the oldest scientific agencies in the United States, and remains the country's leading facility for astronomical and timing data. The observatory is located in Northwest Washington, D.C. at the northwestern end of Embassy Row. It is among the few pre-20th century astronomical observatories located in an urban area. In 1893, in an effort to escape light pollution, it was relocated from Foggy Bottom near the city's center, to its Northwest Washington, D.C. location. The USNO has conducted significant scientific studies throughout its history, including measuring the speed of light, observing solar eclipses, and discovering the moons of Mars. Its achievements include providing data for the first r ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
Astronomical Regulator
A pendulum clock is a clock that uses a pendulum, a swinging weight, as its timekeeping element. The advantage of a pendulum for timekeeping is that it is an approximate harmonic oscillator: It swings back and forth in a precise time interval dependent on its length, and resists swinging at other rates. From its invention in 1656 by Christiaan Huygens, inspired by Galileo Galilei, until the 1930s, the pendulum clock was the world's most precise timekeeper, accounting for its widespread use. Throughout the 18th and 19th centuries, pendulum clocks in homes, factories, offices, and railroad stations served as primary time standards for scheduling daily life, work shifts, and public transportation. Their greater accuracy allowed for the faster pace of life which was necessary for the Industrial Revolution. The home pendulum clock was replaced by less-expensive synchronous electric clocks in the 1930s and 1940s. Pendulum clocks are now kept mostly for their decorative and antique val ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
Electrical Contact
An electrical contact is an Electronic component, electrical circuit component found in electrical switches, relays, Electrical connector, connectors and circuit breakers. Each contact is a piece of electrically conductive material, typically metal. When a pair of contacts touch, they can pass an electrical current with a certain contact resistance, dependent on surface structure, surface chemistry and contact time; when the pair is separated by an insulator (electricity), insulating gap, then the pair does not pass a electric current, current. When the contacts touch, the switch is ''closed''; when the contacts are separated, the switch is ''open''. The gap must be an insulating medium, such as air, vacuum, oil, SF6, SF6. Contacts may be operated by humans in push-buttons and switches, by mechanical pressure in sensors or machine cams, and Electromechanics, electromechanically in relays. The surfaces where contacts touch are usually composed of metals such as silver or gold alloysM ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
