Étienne Lenoir (1744–1832) was a French scientific instrument maker and inventor of the

repeating circle Developed from the reflecting circle, the repeating circle is an instrument for geodetic surveying, invented by Etienne Lenoir in 1784, while an assistant of Jean-Charles de Borda, who later improved the instrument. It was notable as being the ...

.Chronologie scientifique, technologique et économique de la France - Page 137 Danièle et Jean-Claude Clermontel - 2009 "POIDS ET MESURES : le 9 juin 1795, Étienne Lenoir fabrique le premier mètre étalon, sur la base de la mesure du méridien, effectuée en 1754 par l'abbé de La Caille (soit : 5 129 070 toises de Paris, du pôle à l'équateur)." When hired by

Jean-Charles de Borda Jean-Charles, chevalier de Borda (4 May 1733 – 19 February 1799) was a French mathematician, physicist, and Navy officer. Biography Borda was born in the city of Dax to Jean‐Antoine de Borda and Jeanne‐Marie Thérèse de Lacroix. In 17 ...

around 1772 to work on the reflecting circle, he was about thirty years old and nearly illiterate. However, his intelligence and mechanical genius allowed him to perform work that few others could perform. He played a significant role in the improvements to the reflecting circle and later used this experience in inventing the repeating circle. As a result of this work, he became known as the pre-eminent maker of instruments for

astronomy Astronomy () is a natural science that studies celestial objects and phenomena. It uses mathematics, physics, and chemistry in order to explain their origin and evolution. Objects of interest include planets, moons, stars, nebulae, g ...

navigation Navigation is a field of study that focuses on the process of monitoring and controlling the movement of a craft or vehicle from one place to another.Bowditch, 2003:799. The field of navigation includes four general categories: land navigation, ...

and surveying in

France France (), officially the French Republic ( ), is a country primarily located in Western Europe. It also comprises of overseas regions and territories in the Americas and the Atlantic, Pacific and Indian Oceans. Its metropolitan area ...

. In 1787, the king of France appointed him ''certificated engineer to the king''. He created the instruments used on all the major French

geodetic Geodesy ( ) is the Earth science of accurately measuring and understanding Earth's figure (geometric shape and size), orientation in space, and gravity. The field also incorporates studies of how these properties change over time and equivale ...

surveying projects and major naval expeditions of the time. He worked primarily for the ''Commission des Poids et Mesures'' (Weights and Measures Commission) after 1792 and for the Commission du Metre (Metre Commission - for the determination of the metric unit of length, the metre). For these commissions, he produced the instruments used to measure the meridian arc and created the

platinum Platinum is a chemical element with the symbol Pt and atomic number 78. It is a dense, malleable, ductile, highly unreactive, precious, silverish-white transition metal. Its name originates from Spanish , a diminutive of "silver". Pla ...

rules for baseline measurements. In 1793, he made and signed the provisional standard

brass Brass is an alloy of copper (Cu) and zinc (Zn), in proportions which can be varied to achieve different mechanical, electrical, and chemical properties. It is a substitutional alloy: atoms of the two constituents may replace each other wit ...

metre. He also invented a comparator for the measurement of the definitive standard metre. Lenoir was also a member of the ''Commission temporaire des Arts'' (1793–1794). He was made a member of the ''Bureau des Longitudes'' in 1814 and received the Legion of Honour. His son, Paul-Etienne Lenoir, followed in his footsteps, taking over his workshop around 1815 and continuing his work after Lenoir senior's death.

Honours

Lenoir Rock in

Antarctica Antarctica () is Earth's southernmost and least-populated continent. Situated almost entirely south of the Antarctic Circle and surrounded by the Southern Ocean, it contains the geographic South Pole. Antarctica is the fifth-largest cont ...

is named after Étienne Lenoir.

References

*Daumas Maurice, ''Scientific Instruments of the Seventeenth and Eighteenth Centuries and Their Makers'', Portman Books, London 1989 {{DEFAULTSORT:Lenoir, Etienne French scientific instrument makers 1744 births 1832 deaths