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18-inch Borda Repeating Circle, by Troughton, London, Early 19th Century

preview image for 18-inch Borda Repeating Circle, by Troughton, London, Early 19th Century
Inventory Number: 76252
Object Type:
Persons: Troughton
Date Created: Early 19th Century
Place Created: London England United Kingdom Europe
Accession Number: 1931-6/38
Brief Description: Copper alloy repeated circle without reflection, and with painted coating. With 18 inch diameter scale divided on silver and 2 1/8 inch aperture, signed "Troughton London".

This adaptation by Troughton of the Borda circle is based on that produced by the original French maker, Lenoir of Paris. Lenoir's instrument was usually half a metre in diameter, the circle being divided into 400 parts, according to the system adopted by the Academie des Sciences on 27 February 1793.

This type of instrument, sometimes called the repeating land circle, was used for the general purposes of astronomy and topography.
Primary Inscriptions: "Royal Astronomical Society. Presented by Miss Sheepshanks. No. 12" engraved along side of sight. "Troughton London" engraved upon surface of brass circle.
Provenance: Lent by the Royal Astronomical Society in 1931. Presented to the Royal Astronomical Society by Miss Sheepshanks.
Collection Group: Royal Astronomical Society Collection
Material(s): Copper Alloy
Height Width Depth Diameter Unit
830 395 mm


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