Tuning fork watch
A tuning fork watch is a watch with electrically driven tuning fork.
Max Hetzel, an employee of Bulova, since 1953 worked at a mechanism for stabilizing the rate accuracy of a wristwatch by means of an electrically driven tuning fork. 1960 the Bulova Accutron was the first wristwatch with a tuning fork which was brought on the market.
The invention was revolutionary at the time, as it rose the accuracy of the watches above levels known from contemporary mechanical movements. One might therefore regard the tuning fork watch as predecessor to the quartz watch, which then had an even higher precision.