# A report onMarine chronometer

Precision timepiece that is carried on a ship and employed in the determination of the ship's position by celestial navigation.

- Marine chronometer

## John Harrison

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John Harrison (3 April 1693 – 24 March 1776) 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.

## Balance wheel

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Timekeeping device used in mechanical watches and small clocks, analogous to the pendulum in a pendulum clock.

Timekeeping device used in mechanical watches and small clocks, analogous to the pendulum in a pendulum clock.

Until the 1980s balance wheels were the timekeeping technology used in chronometers, bank vault time locks, time fuzes for munitions, alarm clocks, kitchen timers and stopwatches, but quartz technology has taken over these applications, and the main remaining use is in quality mechanical watches.

## Clock

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Device used to measure and indicate time.

Device used to measure and indicate time.

In 1735, Harrison built his first chronometer, which he steadily improved on over the next thirty years before submitting it for examination.

## Longitude

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Geographic coordinate that specifies the east–west position of a point on the surface of the Earth, or another celestial body.

Geographic coordinate that specifies the east–west position of a point on the surface of the Earth, or another celestial body.

In order to perform this calculation, however, one needs a chronometer (watch) set to UTC and needs to determine local time by solar or astronomical observation.

## Escapement

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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.

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 detent or chronometer escapement is considered the most accurate of the balance wheel escapements, and was used in marine chronometers, although some precision watches during the 18th and 19th century also used it.

## Celestial navigation

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Practice of position fixing using stars and other celestial bodies that enables a navigator to accurately determine their actual current physical position in space without having to rely solely on estimated positional calculations, commonly known as "dead reckoning", made in the absence of satellite navigation or other similar modern electronic or digital positioning means.

Practice of position fixing using stars and other celestial bodies that enables a navigator to accurately determine their actual current physical position in space without having to rely solely on estimated positional calculations, commonly known as "dead reckoning", made in the absence of satellite navigation or other similar modern electronic or digital positioning means.

Practical celestial navigation usually requires a marine chronometer to measure time, a sextant to measure the angles, an almanac giving schedules of the coordinates of celestial objects, a set of sight reduction tables to help perform the height and azimuth computations, and a chart of the region.

## Lunar distance (navigation)

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Angular distance between the Moon and another celestial body.

Angular distance between the Moon and another celestial body.

A fuller method was published in 1763 and used until about 1850 when it was superseded by the marine chronometer.

## Greenwich Mean Time

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Mean solar time at the Royal Observatory in Greenwich, London, counted from midnight.

Mean solar time at the Royal Observatory in Greenwich, London, counted from midnight.

As the United Kingdom developed into an advanced maritime nation, British mariners kept at least one chronometer on GMT to calculate their longitude from the Greenwich meridian, which was considered to have longitude zero degrees, by a convention adopted in the International Meridian Conference of 1884.

## Navigation

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Field of study that focuses on the process of monitoring and controlling the movement of a craft or vehicle from one place to another.

Field of study that focuses on the process of monitoring and controlling the movement of a craft or vehicle from one place to another.

Reliable marine chronometers were unavailable until the late 18th century and not affordable until the 19th century.

## Chronometer watch

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Specific type of mechanical timepiece.

Specific type of mechanical timepiece.

The term chronometer is also used to describe a marine chronometer used for celestial navigation and determination of longitude.