A report on Marine chronometer

A marine chronometer by Charles Frodsham of London, shown turned upside down to reveal the movement. Chronometer circa 1844-1860.
The marine "Chronometer" of Jeremy Thacker used gimbals and a vacuum in a bell jar.
Henry Sully (1680-1729) presented a first marine chronometer in 1716
John Harrison's H1 marine chronometer of 1735
Drawings of Harrison's H4 chronometer of 1761, published in The principles of Mr Harrison's time-keeper, 1767.
Ferdinand Berthoud's marine chronometer no.3, 1763
Pierre Le Roy marine chronometer, 1766, photographed at the Musée des Arts et Métiers in Paris
Harrison's Chronometer H5 of 1772, now on display at the Science Museum, London
Ferdinand Berthoud chronometer no. 24 (1782), on display at the Musée des Arts et Métiers, Paris
Einheitschronometer pattern MX6 marine chronometer mass-produced in the Soviet Union after World War II
Mechanical boxed Marine Chronometer used on Queen Victoria's royal yacht, made about 1865
A chronometer mechanism diagrammed (text is in German). Note fusee to transform varying spring tension to a constant force
Einheitschronometer pattern marine chronometer (A. Lange & Söhne, 1948) displaying its second hand advancing in ½ second increments over a 60 seconds marked sub dial for optimal timing of celestial objects angle measurements at the GFZ
Omega 4.19 MHz (4,194,304 = 222 high frequency quartz resonator) Ships Marine Chronometer giving an autonomous accuracy of less than ± 5 seconds per year, French Navy issued,1980. The second hand can advance in ½ second increments for optimal timing of celestial objects angle measurements.
The inner working of a Marine Chronometer

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

- Marine chronometer
A marine chronometer by Charles Frodsham of London, shown turned upside down to reveal the movement. Chronometer circa 1844-1860.

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P. L. Tassaert's half-tone print of Thomas King's original 1767 portrait of John Harrison, located at the Science and Society Picture Library, London

John Harrison

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P. L. Tassaert's half-tone print of Thomas King's original 1767 portrait of John Harrison, located at the Science and Society Picture Library, London
Thomas King's 1767 portrait of John Harrison, located at the Science and Society Picture Library, London
Thomas King's 1767 portrait of John Harrison, located at the Science and Society Picture Library, London
Woodcut of cross section of English longcase (grandfather) clock movement from the mid-1800s
Longitude lines on the globe
Henry Sully's clock (Fig.1) with escapement (Fig.2) and shipboard gimbaled suspension mechanism (Fig.7).
Grasshopper escapement
Harrison's first sea clock (H1)
Harrison's second sea clock (H2)
Harrison's third sea clock (H3)
Drawings of Harrison's H4 chronometer of 1761, published in The principles of Mr Harrison's time-keeper, 1767.
Harrison's "sea watch" No.1 (H4), with winding crank
The clockwork in Harrison's H4 watch
Harrison's Chronometer H5, (Collection of the Worshipful Company of Clockmakers), in the Science Museum, London
A John Harrison ship chronometer
Captain James Cook, painted by Nathaniel Dance-Holland.
Harrison's tomb at St John-at-Hampstead.
Blue plaque in Red Lion Square in London
A modern memorial in Westminster Abbey
Bronze statue of John Harrison in Barrow upon Humber, Lincolnshire
Clock B at the Royal Observatory

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.

Foliot (horizontal bar with weights) from De Vick clock, built 1379, Paris

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.

Foliot (horizontal bar with weights) from De Vick clock, built 1379, Paris
Perhaps the earliest existing drawing of a balance wheel, in Giovanni de Dondi's astronomical clock, built 1364, Padua, Italy. The balance wheel (crown shape, top) had a beat of 2 seconds. Tracing of an illustration from his 1364 clock treatise, Il Tractatus Astrarii.
Early balance wheel with spring in an 18th-century French watch
Bimetallic temperature-compensated balance wheel, from an early 1900s pocket watch. 17 mm dia. (1) Moving opposing pairs of weights closer to the ends of the arms increases temperature compensation. (2) Unscrewing pairs of weights near the spokes slows the oscillation rate. Adjusting a single weight changes the poise, or balance.
Marine chronometer balance wheels from the mid-1800s, with various 'auxiliary compensation' systems to reduce middle temperature error
Low-temperature-coefficient alloy balance and spring, in an ETA 1280 movement from a Benrus Co. watch made in the 1950s

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.

The Shepherd Gate Clock at the Royal Observatory, Greenwich

Clock

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Device used to measure and indicate time.

Device used to measure and indicate time.

The Shepherd Gate Clock at the Royal Observatory, Greenwich
Clock face of the Elizabeth Tower in London, also known as Big Ben
Digital clock radio
Clock on the Beaux Arts façade of the Gare d'Orsay from Paris
24-hour clock face in Florence
Simple horizontal sundial
The flow of sand in an hourglass can be used to keep track of elapsed time
A water clock for goldbeating goldleaf in Mandalay (Myanmar)
A scale model of Su Song's Astronomical Clock Tower, built in 11th-century Kaifeng, China. It was driven by a large waterwheel, chain drive, and escapement mechanism
An elephant clock in a manuscript by Al-Jazari (1206 AD) from The Book of Knowledge of Ingenious Mechanical Devices
A 17th-century weight-driven clock
Richard of Wallingford pointing to a clock, his gift to St Albans Abbey
16th-century clock machine Convent of Christ, Tomar, Portugal
Lantern clock, German,
The Dutch polymath and horologist Christiaan Huygens, the inventor of first precision timekeeping devices (pendulum clock and spiral-hairspring watch)
Opened-up pocket watch
Early French electromagnetic clock
Picture of a quartz crystal resonator, used as the timekeeping component in quartz watches and clocks, with the case removed. It is formed in the shape of a tuning fork. Most such quartz clock crystals vibrate at a frequency of 32,768 Hz
Balance wheel, the oscillator in a mechanical mantel clock.
The Shepherd Gate Clock receives its timing signal from within the Royal Observatory, Greenwich.
Synchronous electric clock, around 1940. By 1940 the synchronous clock became the most common type of clock in the U.S.
A modern quartz clock with a 24-hour face
A linear clock at London's Piccadilly Circus tube station. The 24 hour band moves across the static map, keeping pace with the apparent movement of the sun above ground, and a pointer fixed on London points to the current time.
Software word clock
Many cities and towns traditionally have public clocks in a prominent location, such as a town square or city center. This one is on display at the center of the town of Robbins, North Carolina
A Napoleon III mantel clock, from the third quarter of the 19th century, in the Museu de Belles Arts de València from Spain
A monumental conical pendulum clock by Eugène Farcot, 1867. Drexel University, Philadelphia, USA
One mechanical clock (was useful for sailing purposes)
Mechanical digital clock (with rolling numbers)
Matthew Norman carriage clock with winding key
Decorated William Gilbert mantel clock
Digital clock displaying time by controlling valves on the fountain
Simplistic digital clock radio
Diagram of a mechanical digital display of a flip clock

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

A graticule on the Earth as a sphere or an ellipsoid. The lines from pole to pole are lines of constant longitude, or meridians. The circles parallel to the Equator are circles of constant latitude, or parallels. The graticule shows the latitude and longitude of points on the surface. In this example, meridians are spaced at 6° intervals and parallels at 4° intervals.

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.

A graticule on the Earth as a sphere or an ellipsoid. The lines from pole to pole are lines of constant longitude, or meridians. The circles parallel to the Equator are circles of constant latitude, or parallels. The graticule shows the latitude and longitude of points on the surface. In this example, meridians are spaced at 6° intervals and parallels at 4° intervals.

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.

Animation of anchor escapement

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.

Animation of anchor escapement
Animation of a verge escapement
(left) Original drawing from around 1637 of the pendulum clock designed by Galileo, incorporating the escapement. (right) Model of the escapement
Deadbeat escapement. showing: (a) escape wheel (b) pallets (c) pendulum crutch.
Pin wheel escapement of South Mymms tower clock
Duplex escapement, showing (A) escape wheel, (B) locking tooth, (C) impulse tooth, (D) pallet, (E) ruby disk. The pallet and disk are attached to the balance wheel arbor, but the wheel is not shown.
Double three-legged gravity escapement
Illustration of the Constant Escapement by Girard-Perregaux

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.

A diagram of a typical nautical sextant, a tool used in celestial navigation to measure the angle between two objects viewed by means of its optical sight.

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.

A diagram of a typical nautical sextant, a tool used in celestial navigation to measure the angle between two objects viewed by means of its optical sight.
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Using a marine sextant to measure the altitude of the sun above the horizon
Two nautical ship officers "shoot" in one morning with the sextant, the sun altitude (1963)
The relative longitude to a position (for example Greenwich) can be calculated with the position of the sun and the reference time (for example UTC/GMT).

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.

Finding Greenwich time while at sea using a lunar distance. The lunar distance is the angle between the Moon and a star (or the Sun). The altitudes of the two bodies are used to make corrections and determine the time.

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.

Finding Greenwich time while at sea using a lunar distance. The lunar distance is the angle between the Moon and a star (or the Sun). The altitudes of the two bodies are used to make corrections and determine the time.

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

Greenwich clock with standard measurements

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.

Greenwich clock with standard measurements
Clock in Kumasi, Ghana, set to GMT.

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.

Table of geography, hydrography, and navigation, from the 1728 Cyclopaedia, or a Universal Dictionary of Arts and Sciences

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.

Table of geography, hydrography, and navigation, from the 1728 Cyclopaedia, or a Universal Dictionary of Arts and Sciences
Manual navigation through Dutch airspace
A celestial fix will be at the intersection of two or more circles.
The marine sextant is used to measure the elevation of celestial bodies above the horizon.
Radar ranges and bearings can be used to determine a position.
Poor passage planning and deviation from the plan can lead to groundings, ship damage and cargo loss.
Integrated Bridge System, integrated on an Offshore Service Ship

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

Inside a chronometer mechanism

Chronometer watch

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Specific type of mechanical timepiece.

Specific type of mechanical timepiece.

Inside a chronometer mechanism
A 1928 Movado Ermeto mechanical chronometer.

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