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The History of Timekeeping Devices
A plain-language overview of how people measured hours, from shadow sticks and water clocks to mechanical clocks, quartz watches and atomic standards.
Tools and Industry
Clocks and Timekeeping
Devices that measured hours, from shadows to atomic frequencies.
Atomic Clocks and Standard Time
How cesium atomic clocks work, how they came to define the second in 1967, and how they feed the standard time used by networks, satellites and travelers.
Hourglasses and Candle Clocks
A look at simple sand and wax timers, how they worked, their limits, and why hourglasses became a trusted tool on ships and in churches and courts.
Quartz Watches and the Electronic Revolution
How quartz crystal oscillators moved from laboratories into watches in 1969 and the 1970s, and how they shook the traditional mechanical watch industry.
Sundials and Telling Time by Shadow
How ancient Egyptians, Babylonians, Greeks, Romans, Chinese and Indian astronomers read time from shadows, and how sundials were designed and improved.
The Marine Chronometer and the Longitude Problem
Why finding longitude at sea was so hard, how John Harrison and others built sea-going clocks, and how chronometers changed navigation in the 1700s.
The Mechanical Clock and the Verge Escapement
How the verge and foliot escapement let falling weights run clocks in medieval towers, why it was crude, and what we know and don't know about its origins.
The Pendulum Clock and Accurate Time
How Christiaan Huygens and others used the pendulum in the 1650s to make clocks far more accurate, and how later escapements refined the idea.
Water Clocks and the Clepsydra
How outflow and inflow water clocks measured the night hours and timed court speeches in Egypt, Greece, Rome and China, and why they needed constant care.
Wristwatches from Ladies Jewelry to Soldier Gear
How wrist-worn watches went from early jewelry for women to practical military gear, then to everyday wear for men and women in the early twentieth century.
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