Reference Library

How exactly do watches work?

This measurement (as far as recorded history) dates to 3000 BC, it was then the sexagesimal system (based on 60) was implemented by the ancient Sumerians, who in turned passed the knowledge to the Babylonians.  From those humble beginnings man has refined the craft and art of measuring time (termed Horology).

The sun tracking across the sky is a reminder of time passing, thus sundials tracked this by the shadow it cast on a circular scribed circle.  This was first introduced by the ancient Egyptians who divided the day into two 12 hours periods.  Since sundials work poorly (if at all) on cloudy days and certainly not at night, water clocks were an innovation, and one of the earliest forms of time measurement; these were overlapped by “candle clocks”, “timesticks” and “the hourglass” (measuring time by the funneling of sand through a small channel).

Mechanical clocks (using the Verge escapement) were first introduced in Europe in the 14th century; it is from the point that accuracy, craftsmanship and technology (humble at first) began to take shape, evolving during the 16th century into a spring powered clock, then the pocket watch, pendulum clock in the 18th century, quartz clock in the 20th century and the atomic clock which is at the core of modern technology.

But how does it all work and track the measurement of time?

The Pendulum Clock


  • Face (where the hour and minute hands are shown)
  • Weights (or a spring)
  • Pendulum

The weight is at the heart of a pendulum clock, storing “potential energy” when at its peak, then releasing that energy as it slowly falls toward the earth’s center.  It is however the pendulum itself which allows its accuracy, since (established by scientific fact) a pendulum will travel its full swing, based on its length and the force of gravity.  Gravity is constant, thus the length of the pendulum is adjusted to accurately measure the passing of a second, then a minute, then an hour.

Before and After the Quartz Watch

Prior to the invention of the quartz watch in the 1970s, the wind-up-watch was the forefront of technology and time was measured time by an oscillating balance wheel powered by a spring, the energy released through a complex arrangement of gears eventually moving the hands on the face.

It was Bulova who took a bold step from the oscillating wheel to a transistor oscillator (it hummed) that was attached to a tuning fork.  The humming was the transistor oscillating at hundreds of hertz per seconds (many purest missed the ticking sound).  This energy was still released through the intricate integration of cogs and wheels and eventually to the display.

Quartz has an inherent natural property that has made it invaluable in electronics (and eventually in time keeping), when quartz is bent it generates voltage on its surface (called the Piezoelectric effect), the reverse is also true and if voltage is applied (as it is in a watch) the quartz will bend and it is this features that allows time-to-be-measured.  Inside the watch sophisticated electronics amplify the signal and it begins to oscillate.  It is this oscillation (which is nearly a constant), when converted to pulses, drives a very small motor, the motor connects to gears, and the gears to the display mechanism.

The Atomic Clock

While none of us will be wearing an atomic watch in the near future, it is the “Atomic Clock” that drives modern technology.  Without this clock the Internet would cease to function (or at least without accuracy), GPS satellites would not send precise signals and airplanes (or cars that utilize GPS navigation) would likely miss their destination by miles.  When your home power is interrupted, then later restored, clocks in America are reset by the US Naval Observatory’s Master Clock (USNO) and its atomic clock.

Because an atomic clock is based on atoms and their surrounding electrons, the similarity to your everyday clock is the oscillation frequencies, but the accuracy of the atomic clock, as compared to the most sophisticated wrist watch is astronomical in comparison.  An atomic clock, which can be Cesium, Hydrogen or Rubidium, is accurate to plus or minus one second in 20 MILLION YEARS.

A watch works by measuring time as accurately as possible, how that is accomplished is both an art and science.  The art lies in the beauty and craftsmanship of an elegant timepiece, the science is at the very fabric of our universe.  And while time can certainly be measured accurately on planet earth, from a galactic standpoint, as Einstein said, time is still relative.  Who can predict how time will be measured when “The 10,000 Year Clock” begins its journey toward eternity.