Etienne Lenoir (instrument maker)
Encyclopedia
Etienne Lenoir was a French scientific instrument maker and inventor of the repeating circle
.
When hired by Jean-Charles de Borda
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
, navigation
and surveying
in France
.
In 1787, the king of France appointed him certificated engineer to the king. He created the instruments used on all the major French geodetic
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
rule
s for baseline measurements. In 1793, he made and signed the provisional standard brass
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.
He son, Paul-Etienne Lenoir, followed on in his footsteps, taking over his workshop around 1815 and continuing his work after Lenoir senior's death.
Repeating 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 equal of the great theodolite created by the renowned instrument maker, Jesse Ramsden...
.
When hired by Jean-Charles de Borda
Jean-Charles de Borda
Jean-Charles, chevalier de Borda was a French mathematician, physicist, political scientist, and sailor.-Life history:...
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
Astronomy is a natural science that deals with the study of celestial objects and phenomena that originate outside the atmosphere of Earth...
, navigation
Navigation
Navigation is the process of monitoring and controlling the movement of a craft or vehicle from one place to another. It is also the term of art used for the specialized knowledge used by navigators to perform navigation tasks...
and surveying
Surveying
See Also: Public Land Survey SystemSurveying or land surveying is the technique, profession, and science of accurately determining the terrestrial or three-dimensional position of points and the distances and angles between them...
in France
France
The French Republic , The French Republic , The French Republic , (commonly known as France , is a unitary semi-presidential republic in Western Europe with several overseas territories and islands located on other continents and in the Indian, Pacific, and Atlantic oceans. Metropolitan France...
.
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
Geodesy , also named geodetics, a branch of earth sciences, is the scientific discipline that deals with the measurement and representation of the Earth, including its gravitational field, in a three-dimensional time-varying space. Geodesists also study geodynamical phenomena such as crustal...
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
Meridian arc
In geodesy, a meridian arc measurement is a highly accurate determination of the distance between two points with the same longitude. Two or more such determinations at different locations then specify the shape of the reference ellipsoid which best approximates the shape of the geoid. This...
and created the platinum
Platinum
Platinum is a chemical element with the chemical symbol Pt and an atomic number of 78. Its name is derived from the Spanish term platina del Pinto, which is literally translated into "little silver of the Pinto River." It is a dense, malleable, ductile, precious, gray-white transition metal...
rule
Ruler
A ruler, sometimes called a rule or line gauge, is an instrument used in geometry, technical drawing, printing and engineering/building to measure distances and/or to rule straight lines...
s for baseline measurements. In 1793, he made and signed the provisional standard brass
Brass
Brass is an alloy of copper and zinc; the proportions of zinc and copper can be varied to create a range of brasses with varying properties.In comparison, bronze is principally an alloy of copper and tin...
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.
He son, Paul-Etienne Lenoir, followed on in his footsteps, taking over his workshop around 1815 and continuing his work after Lenoir senior's death.