John Harrison
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.
For other people named John Harrison, see John Harrison (disambiguation).
John Harrison
3 April [O.S. 24 March] 1693
24 March 1776 (aged 82)
English
Copley Medal (1749)
Longitude rewards (1737 & 1773)
Harrison's solution revolutionized navigation and greatly increased the safety of long-distance sea travel. The problem he solved had been considered so important following the Scilly naval disaster of 1707 that the British Parliament was offering financial rewards of up to £20,000 (equivalent to £3.97 million in 2024) under the 1714 Longitude Act,[1] though Harrison was never fully able to receive these rewards due to political rivalries.
Harrison presented his first design in 1730, and worked over many years on improved designs, making several advances in time-keeping technology, finally turning to what were called sea watches. Harrison gained support from the Longitude Board in building and testing his designs. Toward the end of his life, he received recognition and a reward from Parliament. Harrison came 39th in the BBC's 2002 public poll of the 100 Greatest Britons.[2]
John Harrison was born in Foulby in the West Riding of Yorkshire, the first of five children in his family.[3] His stepfather worked as a carpenter at the nearby Nostell Priory estate. A house on the site of what may have been the family home bears a blue plaque.[4]
Around 1700, the Harrison family moved to the Lincolnshire village of Barrow upon Humber. Following his father's trade as a carpenter, Harrison built and repaired clocks in his spare time. Legend has it that at the age of six, while in bed with smallpox, he was given a watch to amuse himself and he spent hours listening to it and studying its moving parts.
He also had a fascination with music, eventually becoming choirmaster for the Church of Holy Trinity, Barrow upon Humber.[5]
Harrison built his first longcase clock in 1713, at the age of 20. The mechanism was made entirely of wood. Three of Harrison's early wooden clocks have survived:
The Nostell example, in the billiards room of this stately home, has a Victorian outer case with small glass windows on each side of the movement so that the wooden workings may be inspected.
On 30 August 1718, John Harrison married Elizabeth Barret at Barrow-upon-Humber church. After her death in 1726, he married Elizabeth Scott on 23 November 1726, at the same church.[6]
In the early 1720s, Harrison was commissioned to make a new turret clock at Brocklesby Park, North Lincolnshire. The clock still works, and like his previous clocks has a wooden movement of oak and lignum vitae. Unlike his early clocks, it incorporates some original features to improve timekeeping, for example the grasshopper escapement. Between 1725 and 1728, John and his brother James, also a skilled joiner, made at least three precision longcase clocks, again with the movements and longcase made of oak and lignum vitae. The grid-iron pendulum was developed during this period. Of these longcase clocks:
Harrison was a man of many skills and he used these to systematically improve the performance of the pendulum clock. He invented the gridiron pendulum, consisting of alternating brass and iron rods assembled in such a way that the thermal expansions and contractions essentially cancel each other out. Another example of his inventive genius was the grasshopper escapement, a control device for the step-by-step release of a clock's driving power. Developed from the anchor escapement, it was almost frictionless, requiring no lubrication because the pallets were made from wood. This was an important advantage at a time when lubricants and their degradation were little understood.
In his earlier work on sea clocks, Harrison was continually assisted, both financially and in many other ways, by the watchmaker and instrument maker George Graham. Harrison was introduced to Graham by the Astronomer Royal Edmond Halley, who championed Harrison and his work. This support was important to Harrison, as he was supposed to have found it difficult to communicate his ideas in a coherent manner.
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