force, while later in the running period as the force of the mainspring decreased, the spring would bear against the narrower part of the cam and the opposing force would also decrease. The stackfreed added a lot of friction and probably reduced a clock's running time substantially; it was only used in some German timepieces and was abandoned after about a century.

Fusee

The fusee was a much longer-lasting innovation. This was a cone-shaped pulley that

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