imported>Shaws username: Adding local short description: "Clock developed in the 1760s by James Cox", overriding Wikidata description "Clock"

2024-04-29T13:34:00Z

Adding local short description: "Clock developed in the 1760s by James Cox", overriding Wikidata description "Clock"

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{{Short description|Clock developed in the 1760s by James Cox}}
[[File:Clocks; James Cox's "perpetual motion" self-winding clock. E Wellcome V0023851.jpg|thumb|drawing of Cox's perpetual motion]]
[[File:Cox timepiece winding switch.png|thumb|Cox timepiece winding switch]]

'''Cox's timepiece''' is a [[clock]] developed in the 1760s by [[James Cox (inventor)|James Cox]]. It was developed in collaboration with [[John Joseph Merlin]] (with whom Cox also worked on developing [[automata]]). Cox claimed that his design was a true [[perpetual motion machine]], but as the device is powered from changes in [[atmospheric pressure]] via a [[mercury (element)|mercury]] [[barometer]], this is not the case. The clock still exists, but was deactivated at the time of its relocation to the [[Victoria and Albert Museum]] in London.<ref>{{cite book | last = Ord-Hume | first = Arthur W. J. G. | year = 1977 | title = Perpetual Motion: The History of an Obsession | publisher = St. Martin's Press | location = New York | isbn = 0-312-60131-X}}, p. 118 ({{Google books|022yYXnS_GQC|online copy|page=118}})</ref>

==Design and history==
The clock is similar to other mechanical clocks, except that it [[Automatic watch|does not need winding]]. The change of pressure in the [[Earth's atmosphere]] acts as an external energy source and causes sufficient movement of the winding mechanism. This keeps the [[mainspring]] coiled inside the barrel. The clock is designed to enable the timepiece to run indefinitely and overwinding is prevented by a safety mechanism. The [[Wiktionary:prime mover|prime mover]], encased in a finely detailed clock body, is a [[Fortin mercury barometer]]. The barometer contained 68 [[kilogram]]s (150 [[pound (mass)|pound]]s) of mercury (approximately 5 litres).<ref>{{cite book | last = Bruton | first = Eric | year = 1979 | title = The History of Clocks and Watches | publisher = Rizzoli International Publications | location = New York | isbn = 0-8478-0261-2 | url-access = registration | url = https://archive.org/details/historyofclocksw0000brut }}</ref>

==Similar clocks==
A similar design is [[Cornelis Drebbel]]'s circa 1610 device that told the time, date, and season. The gold machine was mounted in a globe on pillars and was powered by changes in air pressure (a sealed glass tub with liquid varied in volume through atmospheric pressure changes, rewinding constantly). It is unknown whether Cox was aware of Drebbel's device.

The [[Atmos clock|Atmos]], manufactured by [[Jaeger LeCoultre]] is a modern clock which is similar to Cox's clock although the main driving force is generated from temperature differential, instead of pressure differential.

==See also==
*[[History of perpetual motion machines]]
*[[Beverly Clock]] (1864)

==References==
{{Reflist}}

==External articles and further reading==
===Journals===
* [[William Nicholson (chemist)|William Nicholson]], "''Concerning those perpetual motions which are produced in machines by the rise and fall of the barometer or thermometrical variations in the dimensions of bodies''". Philosophical Journal.
* William Nicholson, Philosophical Journal, vol I, 1799, p375

===Books===
* Arthur W. J. G. Ord-hume, "''Clockwork Music''", Allen & Unwin, London 1973.
* John Joseph Merlin, "''The Ingenious Mechanick''". The Greater London Council, The Iveagh Bequest, Kenwood, Hampstead Lane, London, © 1985.
* [[Christoph Ransmayr]], "[[Cox (novel)|Cox oder der Lauf der Zeit]]". Fischer, Frankfurt am Main 2016.

===Radio===
*{{cite episode |series=The Engines of Our Ingenuity |series-link=The Engines of Our Ingenuity |credits=John H. Lienhard |network=NPR |station=KUHF-FM Houston |airdate=1991 |number=527 |transcript=Cox's Perpetual-Motion Machine|transcript-url=http://www.uh.edu/engines/epi527.htm}}
*{{cite episode |series=The Engines of Our Ingenuity |series-link=The Engines of Our Ingenuity |credits=John H. Lienhard |network=NPR |station=KUHF-FM Houston |airdate=1991 |number=630 |transcript=John Joseph Merlin |transcript-url=http://www.uh.edu/engines/epi630.htm}}

[[Category:Perpetual motion]]
[[Category:Individual clocks in England]]

Cox's timepiece - Revision history

imported>Shaws username: Adding local short description: "Clock developed in the 1760s by James Cox", overriding Wikidata description "Clock"