Image via Wikipediahttp://www.msnbc.msn.com/id/43532031/ns/technology_and_science-innovation/In between the purely mechanical era and quartz becoming common, clocks that based time on 60 cycle household current were very common.
"Since 1930, electric clocks have kept time based on the rate of the electrical current that powers them. If the current slips off its usual rate, clocks run a little fast or slow. Power companies now take steps to correct it and keep the frequency of the current — and the time — as precise as possible."
In fact, electric clocks can be more accurate than quartz timers. This type of clock still exists, but is much less common than it used to be. Increasingly, consumer devices get time from a cable or phone service, or via the internet.
Power companies are now expected to begin experimenting with reducing the corrections that currently keep the power system's frequency steady.
"wall clocks and those on ovens and coffeemakers — anything that flashes "12:00" when it loses power — may be just a bit off every second, and that error can grow with time."
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