Swiss gold open faced keyless pocket watch Circa 1870

Gold watch with independent dead seconds
–
A wonderful Swiss 18K gold double-train independent dead seconds keyless pocket watch, circa 1870. Sold to Mr E. Bonneault on July 14, 1880. An engine-turned back cover, reeded band, bolt at 2 o’clock on the band to prevent accidental stopping of independent seconds and a hinged gold cuvette. White enamel dial with radial Roman numerals, outer minute track and gold paste-set hands. A gilt brass movement, tandem winding, straight line counterpoised lever escapement, cut bimetallic compensation balance, blued steel Breguet balance spring, 27 jewels, a flirt mounted on the last pinion of the independent dead second’s train engages escape wheel pinion allowing one-second jumps. Cuvette signed.
–
Diameter: 53 mm
–
Signed: Patek, Philippe & Co  Genève
–
The independent dead seconds mechanism in which the movement has two trains, one conventional, and the second with a sweep second hand which can be stopped without stopping the main train, was invented by Moise Pouzait in Geneva in 1776. Adrien Philippe’s independent dead second mechanism differs radically from the conventional one, based on Pouzait’s design. Philippe moved the entire independent train over the centre bridge, allowing more room for the going train and the balance, which is more extensive, allowing for better timekeeping.
–
There are fewer than two dozen recorded independent dead second watches by Patek Philippe, including the first ones made by Patek and Czapek. This watch incorporates Adrien Philippe’s two patents regarding tandem winding: the first, for a free, or slipping mainspring, patented on June 16, 1863, in France, and the second, patented ten years after this watch was made, for winding two mainsprings with one crown, Swiss patent No. 1017 of May 23, 1889. A virtually identical movement, but much later (No. 174021), is illustrated in Patek Philippe, Genève by Martin Huber and Alan Banbery.