The First Clock In America Failed, And It Helped Revolutionize Physics

By developing a temperature-compensated pendulum — where the period of a swing didn’t change even as the temperature did — pendulum clocks could be accurate to within just a few seconds per week. The first American-built clock wouldn’t occur for many decades after that advance, and so the first American timekeeping devices were imported.

Which is why it was such a puzzle when the first pendulum clock was brought from Europe to America. The clock, built and calibrated in the Netherlands, was exquisitely accurate. Sunset/sunrise and moonset/moonrise times were accurate for weeks, with stars rising and setting within a minute of the predicted time without any calibration for approximately a full month. But once that clock arrived in America, was wound, and began ticking, everything began to go wrong.

The pendulum clock, arguably, was the first experimental indication we had that gravity is not uniform over the surface of the Earth. Even before the advances of Isaac Newton, it was known that a pendulum — if the swing is small, the air resistance is negligible, and the temperature and length remain constant — always takes the same amount of time to complete a full swing. But the time it takes a pendulum to swing does vary over the surface of Earth, not only with length, but with two other factors: altitude and latitude.