Rare Swiss double-sided astronomical lever watch Circa 1885

Gold double-sided calendar watch with electric alarm function
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An extremely rare, Swiss 14K gold double-sided astronomical calendar watch, circa 1890. With electric alarm function Avertisseur Electrique et Calendrier, according to the patent of Henri Jacot-Burmann.
Swiss lever movement, face with the rotating beaded bezel with a metal pin as electrical contact, underneath a very solid iron ring. Rare enamel dial with an indication of the moon phase and unusual outer scale with 1/3 seconds division, Roman radial hours, outer minutes track with Arabic five minutes numerals, subsidiary dial for the seconds, blued pear hands, and dial marked Avertisseur Electrique et Calendrier. 14K pink gold case, No.99300, back with spring lid, opened by a pusher in the crown, underneath the calendar with day of the week, date, month and length of the month, glazed.
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Diameter: 50 mm
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Weight: 102 g
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Unsigned
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The patent for the electric alarm was filed by Jacob Burmann Bienne as patent no. 327919 in 1885. The watch was fixed in a special watch stand to receive the electric signal and set off the alarm. Only a few pocket watches with this function are known, all with silver cases.