German precision pocket watch with regulator dial Circa 1796

Brass open faced pocket watch by Johann Heinrich Seyffert
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An important precision pocket watch with regulator dial, this is the earliest known pocket watch by Seyffert with a cylinder escapement and a unique adjustable bimetallic temperature compensation attachment for the hairspring, circa 1796.
The outer case is  gilt brass, applied shagreen. The inner case is silver gilt polished. Enamel dial, Arabic/Roman numerals, auxiliary seconds at 4, gold hands. Full plate movement, keywind, frosted, gilt, signed, chain/fusee, round pillars, cylinder escapement with brass cylinder wheel, three-arm brass balance, bimetallic steel and brass bar for temperature compensation of the hairspring.
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Diameter: 67 mm
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Weight: 170 g
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Signed: Johann Heinrich Seyffert, Dresden