French oignon with straight-line balance spring Circa 1700

A rare French gilt metal oignon pocket watch with straight-line balance spring, circa 1700. Gilt full plate movement, pierced and engraved balance bridge, verge escapement, straight-line balance spring, fine thread regulation to shorten the effective length of the spring. White enamel dial, Roman numerals and later single hand. Later gilt metal case. Movement signed Gloria Rouen.
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