mechanical clock

A pendulum clock uses a pendulum as its time base. From their invention, in 1656, until the 1930s, clocks using pendulum movements were the most accurate. Because of their need to be stationary and immovable while operating, pendulum clocks cannot operate in vehicles; the motion and accelerations of the vehicle will affect the motion and pace of the pendulum, causing inaccuracies. See marine chronometer for a discussion of the problems of navigational clocks.
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