Swiss 18k gold, perpetual calendar with moon phases Circa 1940

Gold complicated lever watch
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A fine and rare yellow gold open faced keyless perpetual calendar watch with moon phases, circa 1940. Manual winding nickel lever movement, swan neck precision regulator, 18 jewels, cut bimetallic compensation balance, silvered Stern Frères dial, applied yellow gold Arabic and dot indexes, four subsidiary dials for a month combined with leap year at 12, date at 3, moon phases combined with constant seconds at 6 and day at 9, 18k yellow gold circular case by Wenger, concave bezel, snap-on back, case, dial and movement signed retailed by Gubelin: Patek Philippe.
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Diameter: 46 mm
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Signed: Patek Philippe Genève
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Accompanied by a Patek Philippe Extract from the Archives confirming the date of sale on July 21st 1942. Production of reference 725 began in 1940 and ceased in the early 1980s. It is interesting to note the similarities in design between the reference 725 pocket watch and its contemporary wristwatch models.  The first series reference 725, to which the present lot belongs, had applied Arabic and dot numerals, similar to those of the famous perpetual calendar reference 1526 wristwatch launched only one year after. The second series of Ref. 725 featured applied baton numerals, a change that was also seen in the last examples of the reference 2497 and the 2438-1 models. Both the first and second series of reference 725 had scooped bezels, another design feature in common with the major complication Patek Philippe wristwatches of the same era. The layout of the present lot is particularly exceptional. Indeed, it is only the second example with tumbling Arabic numerals known to have survived. The other one is illustrated in the Patek Philippe Museum book, The Emergence of the Portable Watch vol. 1, p. 284. Furthermore, the prestigious signature of Gubelin makes the only piece with such a dial.