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Time clock. A time clock, sometimes known as a clock card machine, punch clock, or time recorder, is a device that records start and end times for hourly employees (or those on flexi-time) at a place of business. In mechanical time clocks, this was accomplished by inserting a heavy paper card, called a time card, into a slot on the time clock.
The Shortt–Synchronome clock, an electrical driven pendulum clock designed in 1921, was the first clock to be a more accurate timekeeper than the Earth itself. [167] A succession of innovations and discoveries led to the invention of the modern quartz timer. The vacuum tube oscillator was invented in 1912. [168]
The evolution of United States standard time zone boundaries from 1919 to 2024 in five-year increments. Plaque in Chicago marking the creation of the four time zones of the continental US in 1883 Colorized 1913 time zone map of the United States, showing boundaries very different from today Map of U.S. time zones during between April 2, 2006, and March 11, 2007.
A clock or chronometer is a device that measures and displays time. The clock is one of the oldest 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 millennia .
In several countries the 12-hour clock is the dominant written and spoken system of time, predominantly in nations that were part of the former British Empire, for example, the United Kingdom, Republic of Ireland, the United States, Canada (excluding Quebec), Australia, New Zealand, South Africa, India, Pakistan, and Bangladesh, and others ...
Standard time is the synchronization of clocks within a geographical region to a single time standard, rather than a local mean time standard. Generally, standard time agrees with the local mean time at some meridian that passes through the region, often near the centre of the region. Historically, standard time was established during the 19th ...
The Uniform Time Act of 1966 established the system of uniform daylight saving time throughout the US. [1] In the U.S., daylight saving time starts on the second Sunday in March and ends on the first Sunday in November, with the time changes taking place at 2:00 a.m. local time. With a mnemonic word play referring to seasons, clocks "spring ...
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.