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

.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 Reflecting instruments are those that use mirrors to enhance their ability to make measurements. In particular, the use of mirrors permits one to observe two objects simultaneously while measuring the angular distance between the objects. While re ...

, 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 the phenomena that occur in the cosmos. It uses mathematics, physics, and chemistry in order to explain their origin and their overall evolution. Objects of interest includ ...

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

and

surveying Surveying or land surveying is the technique, profession, art, and science of determining the land, terrestrial Plane (mathematics), two-dimensional or Three-dimensional space#In Euclidean geometry, three-dimensional positions of Point (geom ...

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 ...

. 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 or geodetics is the science of measuring and representing the geometry, gravity, and spatial orientation of the Earth in temporally varying 3D. It is called planetary geodesy when studying other astronomical bodies, such as planets ...

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 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 ...

and created the

platinum Platinum is a chemical element; it has Symbol (chemistry), symbol Pt and atomic number 78. It is a density, dense, malleable, ductility, ductile, highly unreactive, precious metal, precious, silverish-white transition metal. Its name origina ...

rule Rule or ruling may refer to: Human activity * The exercise of political or personal control by someone with authority or power * Business rule, a rule pertaining to the structure or behavior internal to a business * School rule, a rule th ...

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

brass Brass is an alloy of copper and zinc, in proportions which can be varied to achieve different colours and mechanical, electrical, acoustic and chemical properties, but copper typically has the larger proportion, generally copper and zinc. I ...

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 (also known as the Antarctic Ocean), it contains the geographic South Pole. ...

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