{{Infobox person | name = Jean-Joseph Tranchot | image = | caption = | birth_date = {{Birth date|1752|01|02}} | birth_place = [[Kœur-la-Petite]], [[France]] | death_date = {{Death date and age|1815|04|30|1752|01|02}} | death_place = [[Montlhéry]], [[France]] | other_names = | occupation = Cartographer | years_active = | known_for = | notable_works = }}
'''Jean-Joseph Tranchot''' (January 2, 1752 – April 30, 1815) was a French military [[cartographer]]. He is most well known for his topographical survey of the [[Rhineland]] under [[Napoleon]], and his assistance in measuring the [[meridian arc]] of France with astronomer [[Pierre Méchain]] to determine to length of the [[meter]].
==Biography== Tranchot was born on January 2, 1752, in [[Kœur-la-Petite]], [[France]].<ref name="Saarland">{{cite web |title=Saarland Biografien |url=http://www.saarland-biografien.de/frontend/php/ergebnis_detail.php?id=277 |website=www.saarland-biografien.de |access-date=31 August 2021 |language=German}}</ref> His parents were Remigius Tranchot, a carpenter, and Maria Maury.<ref>{{cite book |last1=Willems |first1=Bernhard |title=Colonel Tranchot and the Tranchot Stone on the High Fens |date=1955 |publisher=Eupen |page=3}}</ref>
Tranchot was first employed as a cartographer in 1774 in the triangulation of Corsica, which had been ordered by an edict from the French crown in 1770.<ref name="Augoyat">{{cite book |last1=Augoyat |first1=Antoine-Marie |title=Notice sur M. Maissiat, chef d'escadron au Corps royal des ingénieurs-géographes militaires, suivie de notices sur la carte des ex-quatre départemens réunis de la rive gauche du Rhin, et sur M. Tranchot, colonel au Corps royal des ingénieurs-géographes militaires |date=1822 |publisher=Anselin er Pochard |location=Paris |url=https://gallica.bnf.fr/ark:/12148/bpt6k5624353d/f45.item |access-date=31 August 2021 |language=French}}</ref> Upon completion of this task, Tranchot studied astronomy with [[Pierre Méchain]] before he was given orders to triangulate and link his Corsica map with neighboring Sardinia and coastal Tuscany. This task was completed with use of a new invention, the [[repeating circle]],<ref name="Alder">{{cite book |last1=Alder |first1=Ken |title=The Measure of All Things : The Seven-Year Odyssey and Hidden Error that Transformed the World |date=2002 |publisher=Free Press |location=New York |isbn=978-0743216760}}</ref> from 1788 to 1791, and he was subsequently recognized by the Méchain and the [[French Academy of Sciences]] for his work.<ref name="Augoyat" />
Following the cartography of these Mediterranean islands, Tranchot was approached by the French Academy of Sciences to accompany Méchain as his primary adjutant in measuring the southern part of meridian arc of France. This project, spanning 1791 to 1799, started in [[Barcelona]] and ended at [[Rodez]], and the resulting measurement became the basis for the metric system's unit of length, the meter.<ref name="Alder" /> Alongside working with Méchain, Tranchot assisted [[Jean Baptiste Joseph Delambre]] in measuring the baseline at [[Perpignan]] to assist in the meridian survey.<ref name="Alder" />
In 1794, Tranchot was appointed to the scientific staff of the [[Dépôt de la Guerre]].<ref name="Saarland" /> By 1801, the French government under [[Napoleon]] promoted him to the rank of Colonel and tasked him with mapping the [[Rhineland]]'s topography.<ref>{{cite book |title=Antologia Militare |date=1 February 2020 |pages=21–22 |url=https://www.nam-sism.org/Articoli/NAM%20695%20Articolo%20n.%201%20%20-%20FARRUGGIA.pdf |access-date=31 August 2021}}</ref> This final work lasted from 1801 until 1814. In this time, Tranchot completed 167 maps of the area, now known as the "Tranchot Maps". The project was finished in 1828 by [[Karl Freiherr von Müffling]].<ref name="Saarland" />
Tranchot died in 1815 from a stroke.
==Tranchot Maps== <gallery mode=nolines> File:Tranchot uebersicht.svg|Rhineland quadrants surveyed by Tranchot File:Trk5-Kleve B1.jpg|Survey of [[Kleve|Kleve, Germany]] File:TrK70-Bergheim C2.jpg|Survey of [[Bergheim, North Rhine-Westphalia|Bergheim, Germany]] </gallery>
==References== {{Commons category|Tranchot Maps}} {{Reflist}}
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{{DEFAULTSORT:Tranchot, Jean-Joseph}} [[Category:1752 births]] [[Category:1815 deaths]] [[Category:French cartographers]] [[Category:French surveyors]]