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John Harrison (3 April [ O.S. 24 March] 1693 – 24 March 1776) 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. Harrison's solution revolutionized navigation and greatly increased the safety of long-distance sea travel.
Chronometer circa 1844-1860. 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.
The military time zones are a standardized, uniform set of time zones for expressing time across different regions of the world, named after the NATO phonetic alphabet. The Zulu time zone (Z) is equivalent to Coordinated Universal Time (UTC) and is often referred to as the military time zone. The military time zone system ensures clear ...
IRIG J-1 timecode consists of 15 characters (150 bit times), sent once per second at a baud rate of 300 or greater: <SOH>DDD:HH:MM:SS<CR><LF>. SOH is the ASCII "start of header" code, with binary value 0x01. DDD is the ordinal date (day of year), from 1 to 366. HH, MM and SS are the time of the start bit.
Coordinated Universal Time ( UTC) is the primary time standard globally used to regulate clocks and time. It establishes a reference for the current time, forming the basis for civil time and time zones. UTC facilitates international communication, navigation, scientific research, and commerce. UTC has been widely embraced by most countries and ...
The equation of time was engraved on sundials so that clocks could be set using the Sun. In 1720, Joseph Williamson claimed to have invented a clock that showed solar time, fitted with a cam and differential gearing, so that the clock indicated true solar time. [137] [138] [139]
Universal Time ( UT or UT1) is a time standard based on Earth's rotation. [ 1] While originally it was mean solar time at 0° longitude, precise measurements of the Sun are difficult. Therefore, UT1 is computed from a measure of the Earth's angle with respect to the International Celestial Reference Frame (ICRF), called the Earth Rotation Angle ...
The history of standard time in the United States began November 18, 1883, when United States and Canadian railroads instituted standard time in time zones. Before then, time of day was a local matter, and most cities and towns used some form of local solar time, maintained by some well-known clock (for example, on a church steeple or in a ...