Rare Swiss 18k yellow gold World Time dress watch Circa 1943

Gold lever keyless dress watch 
–
A very fine and rare Swiss, 18K yellow gold keyless World Time dress watch, circa 1943. Sold on September 12th, 1945. Accompanied by the Extract from the Archives. A solid, polished case, back and milled revolving bezel. Brushed silver dial with applied yellow gold dot indexes and Roman quarter-hour numerals, outer Arabic dark and light revolving chapter ring for the day and night hours and the World Time chapter ring, bearing the name of 41 locations around the world and revolving with the bezel according to the Louis Cottier world time patent. Gold Circle & dauphine hands. A rhodium-plated movement, Geneva striping decoration, 18 jewels, straight-line lever escapement, cut bimetallic compensation balance adjusted to heat, cold, isochronism and five positions, blued steel Breguet balance spring with swan-neck micrometre regulator. Dial, case and movement signed.
–
Diameter: 45 mm
–
Signed: Patek, Philippe & Co.  Geneva
–
The World Time system was invented around 1935 by Louis Cottier (1894-1966), a famous independent watchmaker in Geneva. This system was used by Patek Philippe and other major names in the Swiss watch industry, such as Agassiz, Rolex and Vacheron Constantin. Patek Philippe created various series of World Timers from 1937 to the mid-1960s.