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An analog pendulum clock made around 18th century. 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.
Huygens first used a clock to calculate the equation of time (the difference between the apparent solar time and the time given by a clock), publishing his results in 1665. The relationship enabled astronomers to use the stars to measure sidereal time , which provided an accurate method for setting clocks.
Water clocks are one of the oldest time-measuring instruments. [1] The simplest form of water clock, with a bowl-shaped outflow, existed in Babylon , Egypt , and Persia around the 16th century BC. Other regions of the world, including India and China , also provide early evidence of water clocks, but the earliest dates are less certain.
The term is less commonly used for the time display on digital clocks and watches. A second type of clock face is the 24-hour analog dial, widely used in military and other organizations that use 24-hour time. This is similar to the 12-hour dial above, except it has hours numbered 1–24 (or 0–23) around the outside, and the hour hand makes ...
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An hourglass (or sandglass, sand timer, or sand clock) is a device used to measure the passage of time. It comprises two glass bulbs connected vertically by a narrow neck that allows a regulated flow of a substance (historically sand ) from the upper bulb to the lower one due to gravity .