Longitude: The True Story of a Lone Genius Who Solved the Greatest Scientific Problem of His Time

Knowing your longitude for navigation (and related, an accurate mobile clock). While you could use stars to pin point your latitude, there was no reliable way to determine your longitude on sea voyages so it was a dangerous guessing game as to how far you traveled. Get it wrong and you could go off course or fall short of you destination. It wasn't until around 1760 that a clock was invented that allowed for navigators to know how far they had traveled. There's an interesting book by Dava Sobel on the subject. Longitude: The True Story of a Lone Genius Who Solved the Greatest Scientific Problem of His Time https://a.co/d/0fQRkqqd