|
Étienne Lenoir (instrument Maker)
Étienne Lenoir (1744–1832) was a French scientific instrument maker and inventor of the repeating circle.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 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 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
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-Charles de Borda, who later improved the instrument. It was notable as being the equal of the Ramsden surveying instruments#great theodolite, great theodolite created by the renowned instrument maker, Jesse Ramsden. It was used to arc measurement, measure the meridian arc from Dunkirk to Barcelona by Jean Baptiste Joseph Delambre, Jean Baptiste Delambre and Pierre Méchain (see: meridian arc of Delambre and Méchain). Construction and operation The repeating circle is made of two telescopes mounted on a shared axis with scales to measure the angle between the two. The instrument combines multiple measurements to increase accuracy with the following procedure: At this stage, the angle on the instrument is double the angle of interest ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
