Editing John Harrison (section)

== Early life ==
{{No footnotes|section|date=April 2018}}
[[File:Longcase clock movement.png|thumb|Woodcut of cross section of English longcase (grandfather) clock movement from the mid-1800s]]
John Harrison was born in [[Foulby]] in the [[West Riding of Yorkshire]], the first of five children in his family.<ref name="britannica.com">{{Cite web|title=John Harrison {{!}} British horologist {{!}} Britannica|url=https://www.britannica.com/biography/John-Harrison-British-horologist|access-date=2021-12-11|website=www.britannica.com|language=en}}</ref> 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]].<ref>{{cite news|url=https://www.bbc.co.uk/bradford/content/articles/2009/04/06/nostell_john_harrison_feature.shtml |title=John Harrison: Timekeeper to Nostell and the world!|work=BBC Bradford and West Yorkshire|publisher=BBC|date= 8 April 2009|access-date= 10 February 2012}}</ref> 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 [[clock]]s 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 [[Conducting|choirmaster]] for the [[Church of Holy Trinity, Barrow upon Humber]].<ref>{{cite book | author=Sobel, Dava | title=Longitude: The True Story of a Lone Genius Who Solved the Greatest Scientific Problem of His Time | location=New York | publisher=Penguin | year=1995 | isbn=0-14-025879-5 | url=https://archive.org/details/longitudetruest000sobe }}</ref> 

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 first (1713) is in the [[Worshipful Company of Clockmakers]]' collection, previously in the Guildhall in London and since 2015 on display in the [[Science Museum, London|Science Museum]].
* The second (1715) is also in the Science Museum in London
* the third (1717) is at Nostell Priory in Yorkshire, the face bearing the inscription "John Harrison Barrow".

The Nostell example, in the [[billiards]] room of this stately home, has a [[Victorian decorative arts|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.<ref>{{Cite book|last=Whittle|first=Eric|title=The Inventor of the Marine Chronometer: John Harrison of Foulby (1693-1776)|publisher=Wakefield Historical Publications|year=1984|isbn=0-901869-18-X|pages=6–8}}</ref>

In the early 1720s, Harrison was commissioned to make a new [[turret clock]] at [[Brocklesby Hall]], 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 clock]]s, again with the movements and longcase made of oak and lignum vitae. The [[gridiron pendulum|grid-iron pendulum]] was developed during this period. Of these longcase clocks:
* Number 1 is in a private collection. Until 2004, it belonged to the Time Museum (USA), which closed in 2000.
* Number 2 is in the [[Leeds City Museum]], as the centrepiece of a permanent display dedicated to John Harrison's achievements. The exhibition, "John Harrison: The Clockmaker Who Changed the World", opened on 23 January 2014. It was the first longitude-related event marking the tercentenary of the Longitude Act.
* Number 3 is in the collection of the Worshipful Company of Clockmakers'.

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 (clockmaker)|George Graham]]. Harrison was introduced to Graham by the [[Astronomer Royal]] [[Edmond Halley]], who championed Harrison and his work. The support was important to Harrison, as he was supposed to have found it difficult to communicate his ideas in a coherent manner.