English technically interesting pocket chronometer Circa 1830

Silver open faced pocket watch by Robert Pennington
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A very heavy and technically highly interesting English pocket watch chronometer, formerly noblemen’s possession, circa 1830.
Silver case, high-grade gold hinges, coat of arms with 9-point crown (count) on back, casemaker’s punch CH, English hallmarks 1830. Full plate movement, chain/fusee with “Harrisons constant force”, spring detent escapement, Pennington secondary deviation compensation balance, blued, curved, and free helical hairspring (a special feature by Pennington), diamond endstone. Enamel dial, Roman hours, Arabic minutes, sunk subsidiary dial with Arabic seconds, blued steel hands.
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Diameter: 63 mm
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Weight: 219 g
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Signed: Robert Pennington, London
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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.