Early Races were being mostly timed by stopwatches mounted to vehicle dashboards, but since the complication was shrunk, they ended up more frequently seen on wrists, specifically in the F1 and endurance racing heyday among the ’50s and ’70s. Impressed by British pilot’s watches through the 1970s, Hamilton’s Khaki Aviation https://www.watchesworld.com/understanding-the-complex-world-of-chronometers/