Swiss rose gold keyless lever with linear calendar Circa 1890

Gold pocket watch with American perpetual calendar
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A fine and unusual Swiss 18 carat rose gold open faced keyless lever pocket watch with linear calendar, circa 1890. The polished case with a hinged gold cuvette. White enamel dial with Roman hour numerals, an outer minute track, Arabic five minute numerals, apertures below 12 o’clock for the days of the week, date and months of the year, subsidiary seconds at 6 o’clock and yellow gold spade hands. A frosted gilt movement with 18 jewels, wolf’s tooth winding, counterpoised straight line lever escapement, cut bimetallic compensation balance, steel Breguet balance spring and an index regulator. Case hallmarked and numbered.
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Diameter: 50 mm
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Signed: No name
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The linear digital calendar or so-called American (perpetual) calendar is a calendar in which the date is displayed in a single linear aperture, allowing for a legible dial to be read at a glance. This type of display was invented in the early Art Deco period and is most often found in watches destined for the Anglo-American market. This kind of calendar became popular once again after the Second World War.