A clock is a device used to measure, verify, keep, and indicate time. The clock is one of the oldest human inventions, meeting the need to measure intervals of time shorter than the natural units: the day, the lunar month, and the year. Devices operating on several physical processes have been used over the millennia.
John Harrison 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.
The second is the base unit of time in the International System of Units (SI), commonly understood and historically defined as 1⁄86400 of a day – this factor derived from the division of the day first into 24 hours, then to 60 minutes and finally to 60 seconds each. Analog clocks and watches often have sixty tick marks on their faces, representing seconds, and a "second hand" to mark the passage of time in seconds. Digital clocks and watches often have a two-digit seconds counter. The second is also part of several other units of measurement like meters per second for speed, meters per second per second for acceleration, and cycles per second for frequency.
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.
Horology is the study of the measurement of time. Clocks, watches, clockwork, sundials, hourglasses, clepsydras, timers, time recorders, marine chronometers, and atomic clocks are all examples of instruments used to measure time. In current usage, horology refers mainly to the study of mechanical time-keeping devices, while chronometry more broadly includes electronic devices that have largely supplanted mechanical clocks for the best accuracy and precision in time-keeping.
A clockmaker is an artisan who makes and/or repairs clocks. Since almost all clocks are now factory-made, most modern clockmakers only repair clocks. Modern clockmakers may be employed by jewellers, antique shops, and places devoted strictly to repairing clocks and watches. Clockmakers must be able to read blueprints and instructions for numerous types of clocks and time pieces that vary from antique clocks to modern time pieces in order to fix and make clocks or watches. The trade requires fine motor coordination as clockmakers must frequently work on devices with small gears and fine machinery.
The grasshopper escapement is a low-friction escapement for pendulum clocks invented by British clockmaker John Harrison around 1722. An escapement, part of every mechanical clock, is the mechanism that gives the clock's pendulum periodic pushes to keep it swinging, and each swing releases the clock's gears to move forward by a fixed amount, thus moving the hands forward at a steady rate. The grasshopper escapement was used in a few regulator clocks built during Harrison's time, and a few others over the years, but has never seen wide use. The term "grasshopper" in this connection, apparently from the kicking action of the pallets, first appears in the Horological Journal in the late 19th century.
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 first mechanical escapement, the verge escapement, was invented in medieval Europe during the 13th century, and was the crucial innovation which led to the development of the mechanical clock. The design of the escapement has a large effect on a timepiece's accuracy, and improvements in escapement design drove improvements in time measurement during the era of mechanical timekeeping from the 13th through the 19th century.
A pocket watch is a watch that is made to be carried in a pocket, as opposed to a wristwatch, which is strapped to the wrist.
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.
The Buddhist calendar is a set of lunisolar calendars primarily used in mainland Southeast Asian countries of Cambodia, Laos, Myanmar and Thailand as well as in Sri Lanka and Chinese populations of Malaysia and Singapore for religious or official occasions. While the calendars share a common lineage, they also have minor but important variations such as intercalation schedules, month names and numbering, use of cycles, etc. In Thailand, the name Buddhist Era is a year numbering system shared by the traditional Thai lunisolar calendar and by the Thai solar calendar.
In horology, a complication is any feature of a mechanical timepiece beyond the display of hours, minutes and seconds. A timepiece indicating only hours, minutes and seconds is known as a simple movement. Common complications include date or day-of-the-week indicators, alarms, chronographs (stopwatches), and automatic winding mechanisms. Complications may be found in any mechanical clock, but they are most notable in mechanical watches where the small size makes them difficult to design and assemble. A typical date-display chronograph may have up to 250 parts, while a particularly complex watch may have a thousand or more parts. Watches with several complications are referred to as grandes complications.
In sociology and anthropology, time discipline is the general name given to social and economic rules, conventions, customs, and expectations governing the measurement of time, the social currency and awareness of time measurements, and people's expectations concerning the observance of these customs by others.
The history of watches began in 16th-century Europe, where watches evolved from portable spring-driven clocks, which first appeared in the 15th century.
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.
The National Watch and Clock Museum (NWCM), located in Columbia, Pennsylvania, is one of a very few museums in the United States dedicated solely to horology, which is the history, science and art of timekeeping and timekeepers.
A mechanical watch is a watch that uses a clockwork mechanism to measure the passage of time, as opposed to quartz watches which function electronically via a small battery, 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 is necessary for 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 and enabling the Age of Discovery and Colonialism to accelerate.
A chronometer is a specific type of mechanical timepiece. In Switzerland, only timepieces certified by the Contrôle Officiel Suisse des Chronomètres (COSC) may use the word certified chronometer or officially certified chronometer on them. Outside Switzerland, equivalent bodies, such as the Japan Chronometer Inspection Institute, have in the past certified timepieces to the same internationally recognised standards, although use of the term has not always been strictly controlled.
For thousands of years, devices have been used to measure and keep track of time. The current sexagesimal system of time measurement dates to approximately 2000 BCE from the Sumerians.
