Swiss 18K pink gold complicated lever pocket watch Circa 1880

Gold open faced pocket watch
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A Swiss 18 carat pink gold complicated keyless pocket watch, made by B. Haas in Geneva, circa 1880. A solid, polished case, case back is polished with a chased gold cypher: A.H. White enamel dial with black painted radial Roman numerals for the hours, and small red painted radial Arabic numerals for the minutes from five to five and gold hands. With subsidiary seconds at 6 and five horological complications: Perpetual calendar, Half-instantaneous date of the month (subsidiary dial at 3 o’clock), Day of the week (subsidiary dial at 9 o’clock; indications given in French), Month of the year (subsidiary dial at 12 o’clock; indications given in French), Age and phases of the moon (subsidiary dial, graduated from 0 to 29 ½, and aperture at 6 o’clock). A rhodium plated movement with going barrel, straight line equilibrated lever escapement, cut compensated balance with gold poising screws and blued steel hairspring with terminal curve. Signature on the cuvette.
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Diameter: 52 mm
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Signed: B. Haas  Geneva/Paris
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Accompanied by a copy of the invention patent.
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Benjamin Haas perpetual calendar
Perpetual calendar mechanism based on the English invention patent No. 2 870, delivered on September 30, 1872, to Benjamin Haas Jeune, Paris, for a Improvements in Watches, showing the Date of the Month and Days of the Week.