Robert Pennington, London, Movement No. 4-433, Case No. 4784, 62 mm, 218 g, circa 1810

A rare and heavy pocket chronometer with spring detent escapement according to Thomas Earnshaw
Case: silver, tiered, engraved crest and crown, gold hinges. Dial: enamel, radial Roman hours, auxiliary seconds, blued spade hands. Movm.: full plate movement, keywind, gilt, signed, chain/fusee with "Harrison's maintaining power", spring detent escapement, Pennington's auxiliary compensation balance, blued freesprung helical balance spring with a left-hand spiral (special feature by Pennington), chatoned diamond endstone on balance.

Robert Pennington
Robert Pennington was a renowned watchmaker who worked in London from about 1780 to his death in 1813. He is thought to have invented the screw balance - a very early version of which was used in the chronometer we have here. Pennington worked with William Howells and a number of other makers; between 1794 and 1799 the group produced at least 27 examples of Thomas Mudges's 'marine timekeepers' commissioned by Mudge’s son. Pennington also created the magnificent drawings of plates in "A Description with Plates" which Mudge Jr. published in 1799.