Longines Hydroconquest Ref. L3.7184.108.40.206
The bezel is the ring or frame that secures a transparent protective layer of material made of either sapphire crystal, mineral glass or plexiglass over the dial and to the watch case.
There are fixed bezels and rotating bezels. Rotating bezels tend to have indications on them that offer additional functions such as a dive counter or a second time zone indication, among other things. Fixed bezels can also add functionality to a wristwatch with useful indications such as a tachymetre.
Longines is the first to have a wristwatch equipped with a functional rotating bezel and used in aviation for navigational purposes.
Its rotating bezel idea most likely evolved from the Weems Second Setting watch, named after US naval officer Philip van Horn Weems who designed it in 1927. He developed it in collaboration with Longines and it was made in 1929. It had an inner rotating disc with a 60-second scale on the dial.
In 1931, the world’s first wristwatch with a rotating bezel was produced – the Lindbergh Hour Angle Watch reference 3210. The watch, designed by Weems and American aviator Charles Lindbergh, had a bezel calibrated to 15 degrees and an inner rotating disc.
The world’s first wristwatch with a rotating bezel graduated to 60 seconds was the Longines Weems New Second Setting watch reference 4036 protected by the US patent 2008734 issued in 1935. The patent covered a pilot’s navigational aid, a “second-setting” watch, with either an inner rotating disc on the dial or a rotating bezel that could be synchronised with a radio time signal.
Simple measurements of elapsed dive times can be read off the watch by aligning the zero index marker on the rotating bezel with the minute hand. In addition to recording elapsed time, the rotating bezel can serve as a slide rule, an indication for the second time zone and even a compass, among other things.