Learn more about methods of keeping time.

Recording the Passage of Time
Clocks from the Past to the Present
Calenders and Time
Tracking Day and Night with a Geochron
Time of Sunrise and Sunset
Making a Sun Clock
The Invention of the Quartz Watch
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Time and Navigation
Time and Longitude
Find Your Longitude
Navigating with a GPS
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More About Time
Daylight Savings Time
Frequently Asked Questions about Time
An Article about the New Optical Atomic Clock
National Institute of Standards and Technology
International Earth Rotation Service
A History of Atomic Clocks
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