In A while, Arnold’s chronometers would serve important roles in famous voyages, since the devices helped navigators compute their longitude. Declaring the winner on the race to construct the main automated chronograph in 1969 is contentious enterprise, so Zenith’s “El Primero” moniker is arguable. That’s the title on the movement https://www.watchesworld.com/understanding-the-complex-world-of-chronometers/