Pre-Owned Longines Longines Lindbergh Hour Angle 90th Anniversary 40991732/AS09262

In a time before GPS, sailors and aviators had to rely on mathematics, knowledge of celestial bodies, and — perhaps most crucially — a good chronometer to find their way home.

When Charles Lindbergh returned from his pioneering solo flight across the Atlantic, he sought a way to simplify the complicated equations and the array of tools needed to calculate longitude. Approaching Longines, he proposed an unusual timepiece that would allow a navigator to make these calculations quite literally on fly. The result was the Longines ‘Hour Angle’ watch. 

Using the bezel (which featured an ‘equation of time’ scale for calculating the difference between a fluctuating ‘Earth’ day and a standardized 24-hour day); an inner, rotating dial disk for synchronizing the seconds hand; and dial markings that allowed the wearer to calculate his position within the Earth’s 360-degree rotation, a pilot could effectively tell his position at any point mid-flight. Until the advent of LORAN, radio navigation and — much later — GPS, this system was the most effective navigational aid in use. 

Longines has since issued numerous iterations of the Hour Angle, including this particular piece produced to celebrate 90 years since Lindbergh’s famed transatlantic flight. That took 33 hours, 30 minutes, and 29.8 seconds in case you were wondering! This model was released in 2017 and features a 47.5mm stainless steel case with a black PVD bidirectional friction bezel and a large ‘onion’ crown. 

The bezel function allows the wearer to adjust for the daily variations in the equation of time, while the galvanic black disk in the center of the dial rotates to synchronize the seconds with a radio time signal. The watch can thus be used to indicate the hour angle in degrees and in minutes of arc. Amazingly, it can also be used to tell the time!

 Powered by an automatic-winding Calibre L699 movement, it comes fitted with a signed brown leather strap with contrast stitching, as well as a signed buckle. It also comes complete with its inner and outer box set, books, hangtags, strap extension, and is numbered 9 out of 90 pieces produced,

Interesting, vintage-inspired, and cool as hell, the Longines Hour Angle is the perfect watch for those intrigued by horological history or aeronautical adventuring!