Ethan Siegel in Forbes:
For nearly three full centuries, the most accurate way that humanity kept track of time was through the pendulum clock. From its initial development in the 17th century until the invention of quartz timepieces in the 1920s, pendulum clocks became staples of household life, enabling people to organize their schedules according to a universally agreed upon standard. Initially invented in the Netherlands by Christian Huygens all the way back in 1656, their early designs were quickly refined to greatly increase their precision.
But when the first pendulum clock was brought to the Americas, something bizarre happened. The clock, which had worked perfectly well at keeping accurate time in Europe, could be synchronized with known astronomical phenomena, like sunset/sunrise and moonset/moonrise. But after only a week or two in the Americas, it was clear that the clock wasn’t keeping time properly. The first clock in America was a complete failure, but that’s only the beginning of a story that would revolutionize our understanding of the physics of planet Earth.