Question: how are clocks made?

Ruth Elderfield answered on 22 Jun 2015:

Clocks usually require two things. Energy to keep them going an a fixed measure of time that can be counted and displayed by the clock.
There have been many forms of clock through the years.
Sun dials, energy from the sunlight shines down creating a shadow that will form at known points depending upon the time of day.
Candle, incense, sand and water clocks have a material that either burns or flows at a known time, so the candle will burn 2cm every 30 mins or half the water will empty out after 50 mins.
More complicated clocks can have gears and pendulums. The gears are usually supplied with energy by a battery or by a mainspring being wound up, they move around at a set pace, but this is kept correct by the pendulum, which is the main measure of time, we know how long it takes to swing back and forth, so it can be used as the measure of time.
Even more complicated clocks use quartz or atomic energy, the quartz when electricity is added will vibrate a known number of times per second and the atomic energy has particles that switch between positive and negative states in a known about of time. These make sure the gears move round at the right speed and display the right time on the clock face.