PERIOD

The period is the duration of an oscillation complete of the organ regulating organ, that is to say the time that the balance takes to make a back-and-forth movement and return to its starting position, i.e. two beats.

It is the inverse of the frequency : an oscillator beating at 4 Hz has a period of a quarter of a second. The period determines the rate at which the escapement releases the train (wheel train) and thus the unit of time counted by the watch; its consistency directly determines accuracy.

Ideally, the period of the balance-hairspring (balance spring) must remain identical regardless of the amplitude, a property called isochronism and sought through a judicious choice of the hairspring, its terminal curve and its attachment point.

Many factors disturb the period: variations in temperature, position, magnetism, friction and aging of the materials. regulation / Adjustment specifically aims to stabilize the period. This physical quantity, borrowed from oscillator theory, is at the heart of mechanical chronometry.

Useful links:

• The regulating organ
• The hairspring
• Isochronism

The period is the time needed for the regulating organ to complete one oscillation.

The period is the inverse of the frequency:

• If the frequency increases → the period decreases
• If the frequency decreases → the period increases

For example, for a balance oscillating at:

• 4 Hz (28’800 A/h)
  → T = 0.25 second
• 3 Hz (21’600 A/h)
  → T = 0.333 second