The Bulova Watch Co. introduced the Accutron in the early 1970s and donated this example to the Smithsonian in 1973. Its escapement consists of three interconnected electronic tuning forks, the vibrations of which are converted into a rotary motion that turns the hands on the face of the instrument. It is powered by a mercury battery, and is accurate to plus or minus one second per day.
Ref: Marvin E. Whitney, The Ship's Chronometer (Cincinnati, 1985), pp. 313-315.