The Aerospace Engineer of the Enlightenment

Ferdinand Berthoud, the Longitude Problem, and the Birth of Marine Chronometry.

Marine Clock No. 8, Paris, 1777.

In the 18th century, the longitude problem was not an abstract scientific puzzle. It was a geopolitical liability.

Latitude could be measured with tolerable confidence. Longitude could not. Minutes of error became hundreds of miles at sea. Ships vanished on unseen coasts. Fleets missed rendezvous. Trade routes faltered. Na…