Extremely rare Danish silver open faced chronometer Circa 1837

Silver precision watch by Louis Urban Jürgensen
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An extremely rare and early Danish silver open faced precision pocket watch, circa 1837. Full plate movement, key wind, chain and fusee, a spring detent escapement according to Thomas Earnshaw, bimetallic chronometer balance, free-sprung blued helical balance spring. The dust cover is secured by a screw and bayonet fitting. White enamel dial with Roman hours, an outer minute track and black moon hands. Polished case with maker’s punch mark LUI with a crown for Louis Urban Jürgensen and UJKK, the pendant monogrammed LUJ, gold hinges. Dial signed, case numbered. Comes with the original mahogany presentation box.
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Diameter: 60 mm
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Weight: 204 g
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Signed: Urban Jürgensen sönner Kjöbenhavn
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Probably at the special request of a customer, Louis Urban Jürgensen regulated the watch for special astronomical use for sidereal time.
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It was Urban Jürgensen’s wish, when he died in 1830, that his sons Louis Urban and Jules Frederik would continue the family business together. For that reason, the company was renamed Urban Jürgensens Sønner. However, Jules Frederik remained in Switzerland and Louis Urban Jürgensen ran the company on his own. In 1836 he produced his first sales catalogue. The number engraved on the dust cover is most likely a year date, as such a high movement number is improbable. It would indicate that the watch was produced a year after the catalogue and classed into the catalogue’s second category under ‘Mindre Chronometre til Længdens Bestemmelse paa Sø- og Land-Reiser til Brug paa Observatorier’ beneath the typical marine chronometer. The quality of this timepiece, however, exceeds the standard described in the catalogue due to some particular features such as the missing movement number, the engraved makers initials in addition to the company signature, some technical specifics as well as the extremely skilled execution.