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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] |
Verge Escapement
The verge (or crown wheel) escapement is the earliest known type of mechanical escapement, the mechanism in a mechanical clock that controls its rate by allowing the gear train to advance at regular intervals or 'ticks'. Verge escapements were used from the late 13th century until the mid 19th century in clocks and pocketwatches. The name verge comes from the Latin ''virga'', meaning stick or rod. Its invention is important in the history of technology, because it made possible the development of all-mechanical clocks. This caused a shift from measuring time by Continuous function, continuous processes, such as the flow of liquid in water clocks, to repetitive, oscillatory processes, such as the swing of pendulums, which had the potential to be more accurate., p.31 Oscillating timekeepers keep time for all modern clocks. Verge and foliot clocks The verge escapement dates from 13th-century Europe, where its invention led to the development of the first all-mechanical clocks ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Balance Wheel
A balance wheel, or balance, is the timekeeping device used in mechanical watches and small clocks, analogous to the pendulum in a pendulum clock. It is a weighted wheel that rotates back and forth, being returned toward its center position by a spiral torsion spring, known as the '' balance spring'' or ''hairspring''. It is driven by the escapement, which transforms the rotating motion of the watch gear train into impulses delivered to the balance wheel. Each swing of the wheel (called a "tick" or "beat") allows the gear train to advance a set amount, moving the hands forward. The balance wheel and hairspring together form a harmonic oscillator, which due to resonance oscillates preferentially at a certain rate, its resonant frequency or "beat", and resists oscillating at other rates. The combination of the mass of the balance wheel and the elasticity of the spring keep the time between each oscillation or "tick" very constant, accounting for its nearly universal use as ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pendulum
A pendulum is a device made of a weight suspended from a pivot so that it can swing freely. When a pendulum is displaced sideways from its resting, equilibrium position, it is subject to a restoring force due to gravity that will accelerate it back toward the equilibrium position. When released, the restoring force acting on the pendulum's mass causes it to oscillate about the equilibrium position, swinging back and forth. The time for one complete cycle, a left swing and a right swing, is called the period. The period depends on the length of the pendulum and also to a slight degree on the amplitude, the width of the pendulum's swing. Pendulums were widely used in early mechanical clocks for timekeeping. The regular motion of pendulums was used for timekeeping and was the world's most accurate timekeeping technology until the 1930s. The pendulum clock invented by Christiaan Huygens in 1656 became the world's standard timekeeper, used in homes and offices for 270 years, and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mechanical Watch
A mechanical watch is a watch that uses a Movement (clockwork), clockwork mechanism to measure the passage of time, as opposed to quartz watches which function using the vibration modes of a piezoelectric quartz tuning fork, or radio clock, radio watches, which are quartz watches synchronized to an atomic clock via radio waves. A mechanical watch is driven by a mainspring which must be wound either periodically by hand or via a Automatic watch, self-winding mechanism. Its force is transmitted through a series of gears to power the balance wheel, a weighted wheel which oscillates back and forth at a constant rate. A device called an escapement releases the watch's wheels to move forward a small amount with each swing of the balance wheel, moving the watch's hands forward at a constant rate. The escapement is what makes the 'ticking' sound which is heard in an operating mechanical watch. Mechanical watches evolved in Europe in the 17th century from spring powered clocks, which appe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Clock
A clock or chronometer is a device that measures and displays time. The clock is one of the oldest Invention, human inventions, meeting the need to measure intervals of time shorter than the natural units such as the day, the lunar month, and the year. Devices operating on several physical processes have been used over the Millennium, millennia. Some predecessors to the modern clock may be considered "clocks" that are based on movement in nature: A sundial shows the time by displaying the position of a shadow on a flat surface. There is a range of duration timers, a well-known example being the hourglass. Water clocks, along with sundials, are possibly the oldest time-measuring instruments. A major advance occurred with the invention of the verge escapement, which made possible the first mechanical clocks around 1300 in Europe, which kept time with oscillating timekeepers like balance wheels., pp. 103–104., p. 31. Traditionally, in horology (the study of timekeeping), the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Astronomical Clock
An astronomical clock, horologium, or orloj is a clock with special mechanisms and dials to display astronomical information, such as the relative positions of the Sun, Moon, zodiacal constellations, and sometimes major planets. Definition The term is loosely used to refer to any clock that shows, in addition to the time of day, astronomical information. This could include the location of the Sun and Moon in the sky, the age and Lunar phases, the position of the Sun on the ecliptic and the current zodiac sign, the sidereal time, and other astronomical data such as the Moon's nodes for indicating eclipses), or a rotating star map. The term should not be confused with an ''astronomical regulator'', a high precision but otherwise ordinary pendulum clock used in observatories. Astronomical clocks usually represent the Solar System using the geocentric model. The center of the dial is often marked with a disc or sphere representing the Earth, located at the center of the S ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Armillary Sphere
An armillary sphere (variations are known as spherical astrolabe, armilla, or armil) is a model of objects in the sky (on the celestial sphere), consisting of a spherical framework of rings, centered on Earth or the Sun, that represent lines of celestial longitude and latitude and other astronomically important features, such as the ecliptic. As such, it differs from a celestial globe, which is a smooth sphere whose principal purpose is to map the constellations. It was invented separately, in ancient China possibly as early as the 4th century BC and ancient Greece during the 3rd century BC, with later uses in the Islamic world and Medieval Europe. With the Earth as center, an armillary sphere is known as '' Ptolemaic''. With the Sun as center, it is known as '' Copernican''. The flag of Portugal features an armillary sphere. The armillary sphere is also featured in Portuguese heraldry, associated with the Portuguese discoveries during the Age of Exploration. Manuel I of Po ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Anchor Escapement Animation 217x328px
An anchor is a device, normally made of metal, used to secure a vessel to the bed of a body of water to prevent the craft from drifting due to wind or current. The word derives from Latin ', which itself comes from the Greek (). Anchors can either be temporary or permanent. Permanent anchors are used in the creation of a mooring, and are rarely moved; a specialist service is normally needed to move or maintain them. Vessels carry one or more temporary anchors, which may be of different designs and weights. A sea anchor is a drag device, not in contact with the seabed, used to minimize drift of a vessel relative to the water. A drogue is a drag device used to slow or help steer a vessel running before a storm in a following or overtaking sea, or when crossing a bar in a breaking sea. Anchoring Anchors achieve holding power either by "hooking" into the seabed, or weight, or a combination of the two. The weight of the anchor chain can be more than that of the anc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Drive Wheel
A drive wheel is a wheel of a motor vehicle that transmits force, transforming torque into tractive force from the tires to the road, causing the vehicle to move. The powertrain delivers enough torque to the wheel to overcome stationary forces, resulting in the vehicle moving forwards or backwards. A two-wheel drive vehicle has two driven wheels, typically both at the front or back, while a four-wheel drive has four. A steering wheel is a wheel that turns to change the direction of a vehicle. A trailer wheel is one that is neither a drive wheel, nor a steer wheel. Front-wheel drive vehicles typically have the rear wheels as trailer wheels. Drive wheel configurations Front-wheel drive Front-wheel drive (FWD) vehicles' engines drive the front wheels. Using the front wheels for delivery of power as well as steering allows the driving force to act in the same direction as the wheel is pointing. This layout is commonly used in modern passenger cars. A rare example of front ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Song Dynasty
The Song dynasty ( ) was an Dynasties of China, imperial dynasty of China that ruled from 960 to 1279. The dynasty was founded by Emperor Taizu of Song, who usurped the throne of the Later Zhou dynasty and went on to conquer the rest of the Five Dynasties and Ten Kingdoms period#Ten Kingdoms, Ten Kingdoms, ending the Five Dynasties and Ten Kingdoms period. The Song frequently came into conflict with the contemporaneous Liao dynasty, Liao, Western Xia and Jin dynasty (1115–1234), Jin dynasties in northern China. After retreating to southern China following attacks by the Jin dynasty, the Song was eventually conquered by the Mongol-led Yuan dynasty. The History of the Song dynasty, dynasty's history is divided into two periods: during the Northern Song (; 960–1127), the capital was in the northern city of Bianjing (now Kaifeng) and the dynasty controlled most of what is now East China. The #Southern Song, 1127–1279, Southern Song (; 1127–1279) comprise the period following ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Zhang Sixun
Zhang Sixun (, fl. 10th century) was a Chinese astronomer and mechanical engineer from Bazhong, Sichuan during the early Song dynasty (960–1279 AD).Liu, 577. He is credited with creating an armillary sphere for his astronomical clock tower that employed the use of liquid mercury (dripped periodically from a clepsydra clock).Needham, Volume 4, 469-471. The liquid mercury filled scoops of the waterwheel would rotate and thus provide the effect of an escapement mechanism in clockworks and allow the astronomical armillary sphere to rotate as needed. Life and works According to the '' History of Song'', Zhang Sixun passed the state examinations in astronomy and mathematics, for this he was appointed to service in the national astronomical observatory (Si Tian Jian), within two years of taking office he had finished construction of an armillary sphere either in 977 or 979. As a result, he was rewarded as assistant to the Astronomical Bureau. Zhang Sixun, although innovative, built ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ahmad Y
Ahmad () is an Arabic male given name common in most parts of the Muslim world. Other English spellings of the name include Ahmed. It is also used as a surname. Etymology The word derives from the root ( ḥ-m-d), from the Arabic (), from the verb (''ḥameda'', "to thank or to praise"), non-past participle (). Lexicology As an Arabic name, it has its origins in a Quranic prophecy attributed to Jesus in the Quran which most Islamic scholars concede is about Muhammad. It also shares the same roots as Mahmud, Muhammad, Hamed, and Hamad. In its transliteration, the name has one of the highest number of spelling variations in the world. Some Islamic traditions view the name Ahmad as another given name of Muhammad at birth by his mother, considered by Muslims to be the more esoteric name of Muhammad and central to understanding his nature. Over the centuries, some Islamic scholars have suggested the name's parallel is in the word 'Paraclete' from the Biblical text,"Isa" ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
