Bulova Accutron (commercial, 1960s)

This is a balance wheel. You'll find one in every watch in the world, every watch. Wine, self-wind, and electric. For the past 300 years, the balance wheel has made every watch in the world either too fast or too slow.

This is a tuning fork. It runs on an electronic circuit and keeps time by vibrations. It divides every second into 360 equal parts. The Accutron timepiece uses this tuning fork instead of the balance wheel, and it's so precise.

We guarantee monthly accuracy within 60 seconds, two seconds a day, and your jeweler will regulate this accuracy free. Accutron issued to X-15 pilots by the United States government.