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

cartographer Cartography (; from grc, χάρτης , "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 im ...

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

Napoleon Napoleon Bonaparte ; it, Napoleone Bonaparte, ; co, Napulione Buonaparte. (born Napoleone Buonaparte; 15 August 1769 – 5 May 1821), later known by his regnal name Napoleon I, was a French military commander and political leader who ...

, and his assistance in measuring the

meridian arc In geodesy and navigation, a meridian arc is the curve between two points on the Earth's surface having the same longitude. The term may refer either to a segment of the meridian, or to its length. The purpose of measuring meridian arcs is to de ...

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 Kœur-la-Petite () is a commune in the Meuse department in Grand Est in north-eastern France. In 1463, during the Wars of the Roses, Kœur became a refuge for members of the defeated House of Lancaster. Henry VI of England's wife, Margaret o ...

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

French Academy of Sciences The French Academy of Sciences (French: ''Académie des sciences'') is a learned society, founded in 1666 by Louis XIV of France, Louis XIV at the suggestion of Jean-Baptiste Colbert, to encourage and protect the spirit of French Scientific me ...

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 and ended at

Rodez Rodez ( or ; oc, Rodés, ) 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 ...

, 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 in measuring the baseline at

Perpignan Perpignan (, , ; ca, Perpinyà ; es, Perpiñán ; it, Perpignano ) is the prefecture of the Pyrénées-Orientales department in southern France, in the heart of the plain of Roussillon, at the foot of the Pyrenees a few kilometres from the ...

to assist in the meridian survey. In 1794, Tranchot was appointed to the scientific staff of the Dépôt de la Guerre. By 1801, the French government under

promoted him to the rank of Colonel and tasked him with mapping the Rhineland'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. 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