The regulator, or oscillator, in a mechanical watch. The balance is a wheel that rotates back and forth on an axle, its motions governed by the coiling and uncoiling of the hairspring, or balance spring. The precision of the timepiece depends to a very large degree upon the construction of the balance. Most modern watches have balances that oscillate 21,600 or 28,800 times per hour (often abbreviated “vph” for “vibrations per hour”), but some have lower or higher frequencies, such as 18,000 or 36,000 vph.
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