QUARTZ
Quartz is a mineral material that is used as a resonator in many electronic watches.
As a resonator it is packed in a vacuum capsule and works thanks to a phenomenon specific to quartz which is piezoelectricity. When we vibrate a quartz it creates electricity and when we inject electricity it vibrates.
It is these vibrations that an integrated circuit can count and then give an impulse to a motor that can display the time. For several decades the most standard frequency of a quartz is 32’768 Hz which corresponds to two power fifteen.
One can sometimes still find chronometers of marine megaquartz where the frequency is 4’194’304 Hz which corresponds to two power twenty-two. There is sometimes this logic of power in the decision of the frequency of a quartz.