Danish massive 18k gold experimental pocket watch Circa 1850

Hunting cased pocket watch by Jules Jürgensen
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A very fine, massive gold, Danish hunting cased experimental pocket watch, circa 1850.
Engine turned 18 carat gold case with hinged cuvette and winding/setting apertures. White enamel dial with Roman hours, auxiliary seconds and blued steel “pear” hands. Signed gilt brass 44.5mm movement with 20 jewels, lever escapement with long fork, temperature compensation balance with gold adjustment screws and Breguet balance spring with experimental very small terminal curve.
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Diameter: 53 mm
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Weight: 120 g
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Signed: Jules Jürgensen, Copenhagen
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Jules Jürgensen was the one who brought horological scientific principles to Le Locle’s horological establishment. Already in 1838, Le Locle’s mayor, Nicolet, wrote about Jürgensen to the canton’s government “…he introduced to us theoretical principles which, if not for him, would not have reached us…”. One of those principles was the material and shape of the balance springs.
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This watch is an example of Jürgensen’s experimentation in this field where he employed an unusual terminal curve with a very small inner radius ending on the third inner coil of the 14-coil spring.