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Isochronous (horology)
A balance spring, or hairspring, is a spring attached to the balance wheel in mechanical timepieces. It causes the balance wheel to oscillate with a resonant frequency when the timepiece is running, which controls the speed at which the wheels of the timepiece turn, thus the rate of movement of the hands. A regulator lever is often fitted, which can be used to alter the free length of the spring and thereby adjust the rate of the timepiece. The balance spring is a fine spiral or helical torsion spring used in mechanical watches, alarm clocks, kitchen timers, marine chronometers, and other timekeeping mechanisms to control the rate of oscillation of the balance wheel. The balance spring is an essential adjunct to the balance wheel, causing it to oscillate back and forth. The balance spring and balance wheel together form a harmonic oscillator, which oscillates with a precise period or "beat" resisting external disturbances, and is responsible for timekeeping accuracy. The additio ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Alarm Clock Balance Wheel
An alarm device is a mechanism that gives an audible, visual or other kind of alarm signal to alert someone to a problem or condition that requires urgent attention. Alphabetical musical instruments Etymology The word ''alarm'' comes from the Old French ''a l'arme'' meaning "to the arms", or "to the weapons", telling armed men to pick up their weapons and get ready for action because an enemy may have suddenly appeared. The word ''alarum'' is an archaic form of ''alarm''. It was sometimes used as a call to arms in the stage directions of Elizabethan dramas. The term comes from the Italian ''all'armi'' and appears 89 times in Shakespeare's first folio. Often explained as the off-stage sounds of conflict or disturbance, recent research suggests a bell or drum may have been used to rouse soldiers from sleep. History and development Early alarm devices were often bells, drums, other musical instruments, or any items which made unusual loud noises that attracted the attention ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mainspring
A mainspring is a spiral torsion spring of metal ribbon—commonly spring steel—used as a power source in mechanical watches, some clocks, and other clockwork mechanisms. ''Winding'' the timepiece, by turning a knob or key, stores energy in the mainspring by twisting the spiral tighter. The force of the mainspring then turns the clock's wheels as it unwinds, until the next winding is needed. The adjectives wind-up and spring-powered refer to mechanisms powered by mainsprings, which also include kitchen timers, metronomes, music boxes, wind-up toys and clockwork radios. Modern mainsprings A modern watch mainspring is a long strip of hardened and blued steel, or specialised steel alloy, 20–30 cm long and 0.05-0.2 mm thick. The mainspring in the common 1-day movement is calculated to enable the watch to run for 36 to 40 hours, i.e. 24 hours between daily windings with a power-reserve of 12 to 16 hours, in case the owner is late winding the watch. This is th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bimetallic Strip
A bimetallic strip is used to convert a temperature change into mechanical displacement. The strip consists of two strips of different metals which expand at different rates as they are heated. The different expansions force the flat strip to bend one way if heated, and in the opposite direction if cooled below its initial temperature. The metal with the higher coefficient of thermal expansion is on the outer side of the curve when the strip is heated and on the inner side when cooled. The invention of the bimetallic strip is generally credited to John Harrison, an eighteenth-century clockmaker who made it for his third marine chronometer (H3) of 1759 to compensate for temperature-induced changes in the balance spring. Harrison's invention is recognized in the memorial to him in Westminster Abbey, England. This effect is used in a range of mechanical and electrical devices. Characteristics The strip consists of two strips of different metals which expand at different rate ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Modulus Of Elasticity
An elastic modulus (also known as modulus of elasticity) is the unit of measurement of an object's or substance's resistance to being deformed elastically (i.e., non-permanently) when a stress is applied to it. The elastic modulus of an object is defined as the slope of its stress–strain curve in the elastic deformation region: A stiffer material will have a higher elastic modulus. An elastic modulus has the form: :\delta \ \stackrel\ \frac where stress is the force causing the deformation divided by the area to which the force is applied and strain is the ratio of the change in some parameter caused by the deformation to the original value of the parameter. Since strain is a dimensionless quantity, the units of \delta will be the same as the units of stress. Specifying how stress and strain are to be measured, including directions, allows for many types of elastic moduli to be defined. The three primary ones are: # ''Young's modulus'' (E) describes tensile and compressi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Big Ben
Big Ben is the nickname for the Great Bell of the Great Clock of Westminster, at the north end of the Palace of Westminster in London, England, and the name is frequently extended to refer also to the clock and the clock tower. The official name of the tower in which Big Ben is located was originally the Clock Tower, but it was renamed Elizabeth Tower in 2012 to mark the Diamond Jubilee of Elizabeth II. The tower was designed by Augustus Pugin in a neo-Gothic style. When completed in 1859, its clock was the largest and most accurate four-faced striking and chiming clock in the world. The tower stands tall, and the climb from ground level to the belfry is 334 steps. Its base is square, measuring on each side. Dials of the clock are in diameter. All four nations of the UK are represented on the tower on shields featuring a rose for England, thistle for Scotland, shamrock for Ireland, and leek for Wales. On 31 May 2009, celebrations were held to mark the tower's 150th annive ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Edward John Dent
Edward John Dent (1790–1853) was a famous English watchmaker noted for his highly accurate clocks and marine chronometers. He founded the Dent company. Early years Edward John Dent, son of John and Elizabeth Dent, was born in London on 19 August 1790. He was baptised on 18 October 1790, at St. Clement Danes Church in the Strand. Edward had a younger brother, William (born 11 February 1792). The boys' mother, Elizabeth, died while they were still young – she was buried on 16 May 1793. Interest in watchmaking At the age of 14, Dent became apprenticed to his grandfather, John Wright Dent, a tallow chandler. Under the terms of the indenture – dated 20 August 1804 – John Wright Dent was expected to find suitable lodgings for his apprentice. Fortunately, Edward John Dent's cousin, Richard Rippon, was willing to have him. Rippon was an expert watchmaker and Dent became fascinated by watchmaking and less interested in the business of making and selling candles. Indeed, D ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
John Harrison
John Harrison ( – 24 March 1776) was a self-educated English carpenter and clockmaker who invented the marine chronometer, a long-sought-after device for solving the problem of calculating longitude while at sea. Harrison's solution revolutionized navigation and greatly increased the safety of long-distance sea travel. The problem he solved was considered so important following the Scilly naval disaster of 1707 that the British Parliament offered financial rewards of up to £20,000 (equivalent to £ in ) under the 1714 Longitude Act. In 1730, Harrison presented his first design, and worked over many years on improved designs, making several advances in time-keeping technology, finally turning to what were called sea watches. Harrison gained support from the Longitude Board in building and testing his designs. Toward the end of his life, he received recognition and a reward from Parliament. Harrison came 39th in the BBC's 2002 public poll of the 100 Greatest Britons. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
John Arnold (watchmaker)
John Arnold (1736 – 11 August 1799) was an English watchmaker and inventor. John Arnold was the first to design a watch that was both practical and accurate, and also brought the term "chronometer" into use in its modern sense, meaning a precision timekeeper. His technical advances enabled the quantity production of marine chronometers for use on board ships from around 1782. The basic design of these has remained, with a few modifications unchanged until the late twentieth century. His legacy includes, together with Abraham-Louis Breguet, as one of the inventors of the modern mechanical watch. One of his most important inventions, the overcoil balance spring is still used in most mechanical wristwatches. It was from around 1770 that Arnold developed the portable precision timekeeper, almost from the point where John Harrison ended his work in this field. But, compared to Harrison's complicated and expensive watch, Arnold's basic design was simple whilst consistently accurate ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Thomas Tompion
Thomas Tompion, FRS (1639–1713) was an English clockmaker, watchmaker and mechanician who is still regarded to this day as the "Father of English Clockmaking". Tompion's work includes some of the most historic and important clocks and watches in the world, and can command very high prices whenever outstanding examples appear at auction. A plaque commemorates the house he shared on Fleet Street in London with his equally famous pupil and successor George Graham. Biography Thomas Tompion was born around 1639 and was baptized on 25 July 1639 in Northill, Bedfordshire, England. The family cottage in Ickwell, his home hamlet in the parish of Northill, bears a plaque erected in his honor by the Worshipful Company of Clockmakers in 1952. He was the eldest son of a blacksmith, also named Thomas Tompion, and probably worked as a blacksmith until 1664 when he became an apprentice of a London clockmaker. Very little of his earlier years is known. The first reference to Tompion i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Worm Drive
A worm drive is a gear train, gear arrangement in which a worm (which is a gear in the form of a Screw thread, screw) meshes with a worm wheel (which is similar in appearance to a gear#Spur, spur gear). The two machine element, elements are also called the worm screw and worm gear. The terminology is often confused by imprecise use of the term ''worm gear'' to refer to the worm, the worm wheel, or the worm drive as a unit. The worm drive or "endless screw" was invented by either Archytas of Terentum, Apollonius of Perga, or Archimedes, the last one being the most probable author.Witold Rybczynski, ''One Good Turn (book), One good turn : a natural history of the screwdriver and the screw''. London, 2000. Page 139. The worm drive later appeared in the Indian subcontinent, for use in roller cotton gins, during the Delhi Sultanate in the thirteenth or fourteenth centuries.Irfan Habib''Economic History of Medieval India, 1200–1500'', page 53 Pearson Education Explanation A tra ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
National Institute Of Standards And Technology
The National Institute of Standards and Technology (NIST) is an agency of the United States Department of Commerce whose mission is to promote American innovation and industrial competitiveness. NIST's activities are organized into Outline of physical science, physical science laboratory programs that include Nanotechnology, nanoscale science and technology, engineering, information technology, neutron research, material measurement, and physical measurement. From 1901 to 1988, the agency was named the National Bureau of Standards. History Background The Articles of Confederation, ratified by the colonies in 1781, provided: The United States in Congress assembled shall also have the sole and exclusive right and power of regulating the alloy and value of coin struck by their own authority, or by that of the respective states—fixing the standards of weights and measures throughout the United States. Article 1, section 8, of the Constitution of the United States, ratified in ... [...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'. Its origin is unknown. 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 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 are used in all modern timepieces. Verge and foliot clocks The verge escapement dates from 13th-century Europe, where its invention led to the development of the first all-mechanica ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
