Swiss silver pocket watch with independent seconds Circa 1877

Silver open faced lever pocket watch
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A very rare Swiss silver open faced keyless winding pocket watch by Patek Philippe, Geneva, circa 1877. A solid, plain case with two horological complications: Dead independent seconds, exterior graduation with central hand, activated by the push piece located on the case band at 4 o’clock. Two mounting barrels in series with unidirectional winding and a free mainspring. White enamel dial with radial Roman numerals, subsidiary seconds at 6 and blued steel Pear hands.
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A gilded brass movement, two going barrels (the one of the dead seconds mechanism with slipping mainspring, so called free spring), double train of wheels, straight line equilibrated lever escapement, cut bimetallic balance with gold poising screws and blued steel hairspring with terminal curve, polished steel index regulator. A custom-made silver 0.925 case, movement in a later working case circa 1919 (with London import letter date for 1919), probably not made by Patek Philippe, with a screwed case back. Originally, the watch was certainly cased in a gold half hunting cased. Signature on the case.
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Diameter: 63 mm
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Weight: 153 g
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Signed: Patek Philippe, Geneva
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This watch is fitted with the new system with two mounting barrels in series with unidirectional winding and a free mainspring, which gives the Swiss invention patent No. 1 017, delivered to Patek Philippe, Geneva, on May 23, 1889. In fact, this invention was already presented by Jean-Adrien Philippe (1815-1894), during the Universal Exhibition of Paris in 1867. This invention dates back to 1866. The Genevan manufacturer will market watches of this type until 1913. As with its mechanism of winding and time-setting at the pendant, nearly a quarter of a century of reflections and improvements led to the final version, that finally patented in 1889. Very few of them were made; this watch is one of the first ten or fifteen produced according to this design.