Swiss bagnolet calibre watch with visible movement Circa 1840

Gold extra flat watch with chain and male key
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A very fine and rare Swiss 18 Carat gold extra flat watch with bagnolet calibre and visible movement. Accompanied by an 18 Carat gold chain and brass female key. Made by Edward Robert Theurer, Chaux-de-Fonds Switzerland Circa 1840. Three body and bassine pincée case with engine-turned back cover and female aperture for winding.
White enamel dial with annular ring with radial Roman numerals, outer minute track and blued steel Breguet hands. Single gilt brass movement with foliate engraved plate, 8 jewels, bar calibre with foliate engraved bridges, plate and barrel, cylinder escapement, three-arm brass balance with flat balance spring and an index regulator.
Movement signed, case numbered.
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Diameter: 44.5 mm
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Thickness (with glass) 5 mm
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Signed: Edward Robert Theurer