Jean-Joseph Tranchot (January 2, 1752 – April 30, 1815) was a French military

cartographer Cartography (; from , 'papyrus, sheet of paper, map'; and , 'write') is the study and practice of making and using maps. Combining science, aesthetics and technique, cartography builds on the premise that reality (or an imagined reality) can ...

. He is most well known for his topographical survey of the

Rhineland The Rhineland ( ; ; ; ) is a loosely defined area of Western Germany along the Rhine, chiefly Middle Rhine, its middle section. It is the main industrial heartland of Germany because of its many factories, and it has historic ties to the Holy ...

under

Napoleon Napoleon Bonaparte (born Napoleone di Buonaparte; 15 August 1769 – 5 May 1821), later known by his regnal name Napoleon I, was a French general and statesman who rose to prominence during the French Revolution and led Military career ...

, and his assistance in measuring the

meridian arc In geodesy and navigation, a meridian arc is the curve (geometry), curve between two points near the Earth's surface having the same longitude. The term may refer either to a arc (geometry), segment of the meridian (geography), meridian, or to its ...

of France with astronomer

Pierre Méchain Pierre François André Méchain (; 16 August 1744 – 20 September 1804) was a French astronomer and surveyor who, with Charles Messier, was a major contributor to the early study of deep-sky objects and comets. Life Pierre Méchain was bo ...

to determine to length of the

meter The metre (or meter in US spelling; symbol: m) is the base unit of length in the International System of Units (SI). Since 2019, the metre has been defined as the length of the path travelled by light in vacuum during a time interval of of ...

Biography

Tranchot was born on January 2, 1752, in Kœur-la-Petite,

France France, officially the French Republic, is a country located primarily in Western Europe. Overseas France, Its overseas regions and territories include French Guiana in South America, Saint Pierre and Miquelon in the Atlantic Ocean#North Atlan ...

. His parents were Remigius Tranchot, a carpenter, and Maria Maury. 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. Upon completion of this task, Tranchot studied astronomy with

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 The repeating circle is an instrument for geodetic surveying, developed from the Reflecting instrument#reflecting circle, reflecting circle by Étienne Lenoir (instrument maker), Étienne Lenoir in 1784. He invented it while an assistant of Jean ...

, from 1788 to 1791, and he was subsequently recognized by the Méchain and the

French Academy of Sciences The French Academy of Sciences (, ) is a learned society, founded in 1666 by Louis XIV at the suggestion of Jean-Baptiste Colbert, to encourage and protect the spirit of French Scientific method, scientific research. It was at the forefron ...

for his work. 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 Barcelona ( ; ; ) is a city on the northeastern coast of Spain. It is the capital and largest city of the autonomous community of Catalonia, as well as the second-most populous municipality of Spain. With a population of 1.6 million within c ...

and ended at

Rodez Rodez (, , ; , ) is a small city and commune in the South of France, about 150 km northeast of Toulouse. It is the prefecture of the department of Aveyron, region of Occitania (formerly Midi-Pyrénées). Rodez is the seat of the communau ...

, and the resulting measurement became the basis for the metric system's unit of length, the meter. Alongside working with Méchain, Tranchot assisted

Jean Baptiste Joseph Delambre Jean Baptiste Joseph, chevalier Delambre (19 September 1749 – 19 August 1822) was a French mathematician, astronomer, historian of astronomy, and geodesist. He was also director of the Paris Observatory, and author of well-known books on the ...

in measuring the baseline at

Perpignan Perpignan (, , ; ; ) is the prefectures in France, prefecture of the Pyrénées-Orientales departments of France, department in Southern France, in the heart of the plain of Roussillon, at the foot of the Pyrenees a few kilometres from the Me ...

to assist in the meridian survey. In 1794, Tranchot was appointed to the scientific staff of the

Dépôt de la Guerre The Dépôt de la Guerre was France's military archive and cartography department, set up in 1688 under Louis XIV and expanded during the French Revolutionary Wars and the Napoleonic Wars. History Established by François Michel Le Tellier de Louvo ...

. By 1801, the French government under

promoted him to the rank of Colonel and tasked him with mapping the

's topography. 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 Friedrich Karl Ferdinand Freiherr von Müffling, nicknamed Weiss (12 June 177510 January 1851), was a Prussian ''Generalfeldmarschall'' and military theorist. He served as Blücher's liaison officer in Wellington's headquarters during the Battle ...

. Tranchot died in 1815 from a stroke.

Tranchot Maps

File:Tranchot uebersicht.svg, Rhineland quadrants surveyed by Tranchot File:Trk5-Kleve B1.jpg, Survey of Kleve, Germany File:TrK70-Bergheim C2.jpg, Survey of Bergheim, Germany

References

{{DEFAULTSORT:Tranchot, Jean-Joseph 1752 births 1815 deaths French cartographers French surveyors