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John Harrison was an English carpenter and clockmaker who invented the marine chronometer, a long-sought-after device for solving the problem of calculating longitude while at sea.
Navigation is a field of study that focuses on the process of monitoring and controlling the movement of a craft or vehicle from one place to another. The field of navigation includes four general categories: land navigation, marine navigation, aeronautic navigation, and space navigation.
Hanlon's razor is an adage or rule of thumb that states:
Murphy's law is an adage or epigram that is typically stated as: "Anything that can go wrong will go wrong." In some formulations, it is extended to "Anything that can go wrong will go wrong, and at the worst possible time."
A watch is a portable timepiece intended to be carried or worn by a person. It is designed to keep a consistent movement despite the motions caused by the person's activities. A wristwatch is designed to be worn around the wrist, attached by a watch strap or other type of bracelet, including metal bands, leather straps, or any other kind of bracelet. A pocket watch is designed for a person to carry in a pocket, often attached to a chain.
A watchmaker is an artisan who makes and repairs watches. Since a majority of watches are now factory-made, most modern watchmakers only repair watches. However, originally they were master craftsmen who built watches, including all their parts, by hand. Modern watchmakers, when required to repair older watches, for which replacement parts may not be available, must have fabrication skills, and can typically manufacture replacements for many of the parts found in a watch. The term clockmaker refers to an equivalent occupation specializing in clocks.
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 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 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 stopping of the escapement's tooth is what generates the characteristic "ticking" sound heard in operating mechanical clocks and watches.
The Contrôle officiel suisse des Chronomètres (COSC), the Official Swiss Chronometer Testing Institute, is the institute responsible for certifying the accuracy and precision of Swiss watches.
A chronograph is a specific type of watch that is used as a stopwatch combined with a display watch. A basic chronograph has an independent sweep second hand and a minute sub-dial; it can be started, stopped, and returned to zero by successive pressure on the stem. More complex chronographs use additional complications and can have multiple sub-dials to measure seconds, minutes, hours and even fractions of a second. In addition, many modern chronographs use moveable bezels as tachymeters for rapid calculations of speed or distance. Louis Moinet invented the chronograph in 1816 for use in tracking astronomical objects. Chronographs were also used heavily in artillery fire in the mid to late 1800s. More modern uses of chronographs involve aircraft piloting, auto racing, diving and submarine maneuvering.
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 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 the timekeeper in mechanical watches to the present. From its invention in the 14th century until tuning fork and quartz movements became available in the 1960s, virtually every portable timekeeping device used some form of balance wheel.
John Arnold was an English watchmaker and inventor.
The Hamilton Watch Company is a Swiss manufacturer of wristwatches based in Bienne, Switzerland. Founded in 1892 as an American firm, the Hamilton Watch Company ended American manufacture in 1969. Through a series of mergers and acquisitions, the Hamilton Watch Company eventually became integrated into the Swatch Group, the world's largest watch manufacturing and marketing conglomerate.
"A language is a dialect with an army and navy", sometimes called the Weinreich witticism, is a quip about the arbitrariness of the distinction between a dialect and a language. It points out the influence that social and political conditions can have over a community's perception of the status of a language or dialect. The facetious adage was popularized by the sociolinguist and Yiddish scholar Max Weinreich, who heard it from a member of the audience at one of his lectures in the 1940s.
In reliability engineering, dual modular redundancy (DMR) is when components of a system are duplicated, providing redundancy in case one should fail. It is particularly applied to systems where the duplicated components work in parallel, particularly in fault-tolerant computer systems. A typical example is a complex computer system which has duplicated nodes, so that should one node fail, another is ready to carry on its work.
In computing, triple modular redundancy, sometimes called triple-mode redundancy, (TMR) is a fault-tolerant form of N-modular redundancy, in which three systems perform a process and that result is processed by a majority-voting system to produce a single output. If any one of the three systems fails, the other two systems can correct and mask the fault.
A mechanical watch is a watch that uses a 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 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 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 appeared in the 15th century.
A marine chronometer is a precision timepiece that is carried on a ship and employed in the determination of the ship's position by celestial navigation. It is used to determine longitude by comparing Greenwich Mean Time (GMT), and the time at the current location found from observations of celestial bodies. When first developed in the 18th century, it was a major technical achievement, as accurate knowledge of the time over a long sea voyage was vital for effective navigation, lacking electronic or communications aids. The first true chronometer was the life work of one man, John Harrison, spanning 31 years of persistent experimentation and testing that revolutionized naval navigation.
Quartz clocks and quartz watches are timepieces that use an electronic oscillator regulated by a quartz crystal to keep time. This crystal oscillator creates a signal with very precise frequency, so that quartz clocks and watches are at least an order of magnitude more accurate than mechanical clocks. Generally, some form of digital logic counts the cycles of this signal and provides a numerical time display, usually in units of hours, minutes, and seconds.
Hard cases make bad law is an adage or legal maxim meaning that an extreme case is a poor basis for a general law that would cover a wider range of less extreme cases. In other words, a general law is better drafted for the average circumstance as this will be more common.
The Omega Marine Chronometer was the first quartz wristwatch ever to be awarded certified status as a marine chronometer. The watch was made by Omega SA and developed by John Othenin-Girard and is one of the most accurate non thermo-compensated production watches ever made, keeping time to within 1 second per month
References
- ↑ Bloch, Arthur (2003). Murphy's Law. New York: Perigee. p. 36. ISBN 978-0-399-52930-6. OCLC 52895461.
- ↑ "Barry Popik".