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Reflecting Circle - click to enlarge

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Reflecting Circle

Catalogue number:

"Le noir AParis no 10"

diameter 10.5 inches

The Chevalier de Borda developed this type of reflecting circle, and published a description of it in Paris in 1787. This example has a silvered scale that is graduated every 20 minutes and read by two verniers with tangent screws and magnifiers to single minutes. It was made by Étienne Lenoir (1744-1832), the French craftsman who is credited with having made Borda’s first instrument of this sort. It belonged to Columbia College (now University) in New York, and probably dates from the 1790s.

Ref: A. J. Turner, From Pleasure and Profit to Science and Security. Étienne Lenoir and the transformation of precision instrument-making in France, 1760-1830 (Cambridge: Whipple Museum of the History of Science, 1989).

Further Information:

Reflecting Circle