Technically interesting English silver pocket chronometer Circa 1830

Silver open faced chronometer by Robert Pennington
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A very heavy and technically highly interesting English silver open faced pocket chronometer, circa 1830. Full plate movement, chain/fusee with Harrison’s constant force, spring detent escapement, Pennington secondary deviation compensation balance, blued, curved, and free helical hairspring (a special feature by Pennington), diamond endstone. White enamel dial with Roman hours and Arabic five minutes, subsidiary seconds, blued steel hands. Case with engraved coat-of-arms on the back, gold hinges, case maker’s punch CH, English hallmarks for 1830. Case numbered, movement signed and numbered.
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Diameter: 63 mm
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Weight: 219 g
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Signed: Pennington London
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Formerly a nobleman’s possession.
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Robert Pennington was a well-known watchmaker who worked in London from about 1780 until his death in 1824. He is known as the inventor of the screw balance, a very early version of it was used in this chronometer watch. Pennington worked with William Howells and a number of other well-known watchmakers. From 1794 to 1799, this group produced at least 27 pieces of Thomas Mudges marine chronometers on behalf of his son. Pennington also created the outstanding plate drawings in ‘A Description with Plates’, published by Mudge jr. in 1799.