German verge watch with calendar and 24h indicator Circa 1790

Silver open faced astronomical pocket watch
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An important and astronomical Swabian verge pocket watch with calendar and 24h indicator by Jacob Auch, circa 1790.
Silver plain tiered case. Enamel dial with double radial Roman hours “I-XII”, Arabic minutes, subsidiary chapter ring with Arabic numerals for date indication, small auxiliary chapter ring with moon phases in combination with the time from moonrise to moonset “the ring is divided into quarters of the night” and filigree hands. Full plate movement, key wind, fire gilt, moulded movement pillars, large three-arm brass balance, pierced balance bridge.
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Diameter: 65 mm
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Weight: 177 g
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Signed: Jacob Auch à Louisbourg
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Jacob Auch was one of the most talented pupil of clergyman and famous precision engineer and watchmaker Phillip Matthaeus Hahn.
He began his apprenticeship in the workshop of Philipp Matthaeus Hahn in Echterdingen. From 1787 until 1798 he had his own small workshop in Vaihingen an der Enz and worked for the Institute of Physics in Karlsruhe. As court mechanic for the Duke of Weimar he worked mainly for the new Seeberg Observatory from 1798 on. The renowned astronomer Baron Franz Xaver von Zach headed the observatory until 1806 and was one of Jacob Auch’s most important customers. Auch supplied numerous watches and instruments for the observatory, which was at the time the most modern in Europe. His work was at the time always measured against the quality of English chronometer makers such as Josiah Emery and Thomas Mudge. Auch also created important astronomer’s pocket watches in the style of his master Philipp Matthaeus Hahn, with dials on both sides. One of the most famous customers of Auch was Johann Wolfgang von Goethe.