John Harrison 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.
The longitude rewards were the system of inducement prizes offered by the British government for a simple and practical method for the precise determination of a ship's longitude at sea. The rewards, established through an Act of Parliament in 1714, were administered by the Board of Longitude.
The Commissioners for the Discovery of the Longitude at Sea, or more popularly Board of Longitude, was a British government body formed in 1714 to administer a scheme of prizes intended to encourage innovators to solve the problem of finding longitude at sea.
Horology is the study of the measurement of time. Clocks, watches, clockwork, sundials, hourglasses, clepsydras, timers, time recorders, marine chronometers, and atomic clocks are all examples of instruments used to measure time. In current usage, horology refers mainly to the study of mechanical time-keeping devices, while chronometry more broadly includes electronic devices that have largely supplanted mechanical clocks for the best accuracy and precision in time-keeping.
George Graham, FRS was an English clockmaker, inventor, and geophysicist, and a Fellow of the Royal Society.
William Derham FRS was an English clergyman, natural theologian, natural philosopher and scientist. He produced the earliest reasonably accurate measurement of the speed of sound.
The grasshopper escapement is a low-friction escapement for pendulum clocks invented by British clockmaker John Harrison around 1722. An escapement, part of every mechanical clock, is the mechanism that gives the clock's pendulum periodic pushes to keep it swinging, and each swing releases the clock's gears to move forward by a fixed amount, thus moving the hands forward at a steady rate. The grasshopper escapement was used in a few regulator clocks built during Harrison's time, and a few others over the years, but has never seen wide use. The term "grasshopper" in this connection, apparently from the kicking action of the pallets, first appears in the Horological Journal in the late 19th century.
Ferdinand Berthoud, was a scientist and watchmaker. He became master watchmaker in Paris in 1753. Berthoud, who held the position of Horologist-Mechanic by appointment to the King and the Navy, left behind him an exceptionally broad body of work, in particular in the field of marine chronometers.
Thomas Earnshaw was an English watchmaker who, following John Arnold's earlier work, further simplified the process of marine chronometer production, making them available to the general public. He is also known for his improvements to the transit clock at the Royal Greenwich Observatory in London and his invention of a chronometer escapement and a form of bimetallic compensation balance.
John Arnold was an English watchmaker and inventor.
The Clockmakers’ Museum in London, England, is believed to be the oldest collection specifically of clocks and watches in the world. The collection belongs to and is administered by the Clockmakers’ Charity, affiliated to the Worshipful Company of Clockmakers, founded in 1631 by Royal Charter. Since 2015 it has been housed in a gallery provided by the Science Museum in South Kensington, having formerly been located in the Guildhall complex in the City of London since 1874, where it first opened to the public. Admission is free.
Charles Frodsham was a distinguished English horologist, establishing the firm of Charles Frodsham & Co, which remains in existence as the longest continuously trading firm of chronometer manufacturers in the world. In January 2018, the firm launched a new chronometer wristwatch, after sixteen years in development. It is the first watch to use the George Daniels double-impulse escapement.
Rupert Thomas Gould was a lieutenant-commander in the British Royal Navy noted for his contributions to horology. He was also an author and radio personality.
Larcum Kendall was a British watchmaker.
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), or in the modern world its successor Coordinated Universal Time (UTC), and the time at the current location found from observations of celestial bodies. When first developed in the 18th century, it was a major technical achievement, as accurate knowledge of the time over a long sea voyage was vital for effective navigation, lacking electronic or communications aids. The first true chronometer was the life work of one man, John Harrison, spanning 31 years of persistent experimentation and testing that revolutionized naval navigation and enabling the Age of Discovery and Colonialism to accelerate.
A chronometer is an extraordinarily accurate timepiece, with an original focus on the needs of maritime navigation. In Switzerland, timepieces certified by the Contrôle Officiel Suisse des Chronomètres (COSC) may be marked as Certified Chronometer or Officially Certified Chronometer. Outside Switzerland, equivalent bodies, such as the Japan Chronometer Inspection Institute, have in the past certified timepieces to similar standards, although use of the term has not always been strictly controlled.
Jonathan Betts MBE is Curator Emeritus at the Royal Observatory, Greenwich, a horological scholar and author, and an expert on the first marine timekeepers created by John Harrison in the middle of the 18th century. He was formerly Senior Specialist in horology at Greenwich. Between 2016 and 2019 he served on the board of trustees of the Institute of Conservation.
The history of timekeeping devices dates back to when ancient civilizations first observed astronomical bodies as they moved across the sky. Devices and methods for keeping time have gradually improved through a series of new inventions, starting with measuring time by continuous processes, such as the flow of liquid in water clocks, to mechanical clocks, and eventually repetitive, oscillatory processes, such as the swing of pendulums. Oscillating timekeepers are used in all modern timepieces.
Pierre Le Roy (1717–1785) was a French clockmaker. He was the inventor of the detent escapement, the temperature-compensated balance and the isochronous balance spring. His developments are considered as the foundation of the modern precision clock. Le Roy was born in Paris, eldest son of Julien Le Roy, a clockmaker to Louis XV who had worked with Henry Sully, in which place Pierre Le Roy succeeded his father. He had three brothers: Jean-Baptiste Le Roy (1720-1800), a physicist; Julien-David Le Roy (1724–1803), an architect; and Charles Le Roy (1726–1779), a physician and encyclopédiste.
Henry Sully (1680–1729) was an English clockmaker. He was an apprentice and then journeyman for celebrated English clockmaker and watchmaker Charles Gretton. He lived in France for many years.
