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Inventory no. 76252 - Former Display Label

English REPEATING CIRCLE
c.1810

Repeating circle without reflection; 18 inch diameter scale divided on silver; telescope 2 1/8 inch aperture; signed "Troughton London". Inscribed "Royal Astronomical Society. Presented by Miss Sheepshanks No. 12".

This adaptation by Troughton of the Borda circle is based on that produced by the original French maker, Lenoir of Paris (see the 5 inch hand circle above). 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.

31.6.38
R.A.S.

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