1940 rare Longines Fly-back cal. 13ZN ref. 23173 39, big 39.5mm case, one of my favorites.

If you think Patek made the best chronographs in the 1940s and 50s youre half right. Patek absolutely made some of the best and still most desirable chronos in the middle part of last century, but there was another manufacturer making truly top-notch stopwatch mechanisms for the wrist, and that was Longines. Yes, Longines.

Longines was one of the premiere manufacturers in the world. And I say “manufacturer” because while even Patek, Vacheron, and AP were using outsourced movements, Longines was indeed one of the few companies manufacturing its own in-house chronograph movements.

Introduced in the 1936, the Caliber 13ZN was a large 13 1/4 ligne movement, the large diameter was purposeful, as the caliber would be placed into several aviation-oriented chronographs. It is a beautifully finished movement, and one of the first “fly-back movements”, meaning it was not required to stop the chronograph before resetting it.
The 13ZN also featured a semi-instantaneous minute hand, so instead of the minute hand creeping along continuously, it would remain in position until the second hand hit 60 and then jump. It may not sound like much, but these details werent seen together again until A. Lange & Sohne released their monumental Datograph.

Longines was founded in 1832, its winged hourglass logo is the oldest registered trademark for a watchmaker.
Longines provided timers used at the first modern Olympics in 1896.
In 1899, a Longines watch went to the North Pole with the Arctic explorer Luigi Amedeo of Savoy.
Charles Lindbergh, after his transatlantic flight, designed a pilot watch to help with air navigation. Built to his specifications, the Longines hour angle was introduced in 1931 and it is still produced today.
The company began to produce military issue watches for the second World War, most for the European forces.
Today Longines is owned by the Swatch Group.