Extremely rare American gold-plated tourbillon watch Circa 1940

\Gold-plated one-minute tourbillon
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An extremely rare American 10 carat gold-plated open faced one-minute tourbillon pocket watch, circa 1940. Glazed bridge movement, a tourbillon, gold screw compensation balance. White enamel dial with Roman hours, outer minute divisions and sunk subsidiary seconds. A hand-engraved and chiselled case, the back is decorated with flowers, leaves and an ornamental band. Dial signed American Watch Co Waltham Mass., movement signed Tourbillon Frank C. Smith 1939, case numbered.
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Diameter: 52 mm
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Weight: 93 g
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Signed: American Watch Co Waltham Mass.
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None of the early pocket watch makers in America had marketable tourbillons in their product range. This timepiece is the only tourbillon known that was produced in the U.S. in the early 1940s. It is possibly a graduation piece created by Frank C. Smith, who applied for a patent for a timer mechanism in 1942.