Sundial
The gnomon's shadow walks across the dial after the Sun.
Read the article →An encyclopedia of clocks
How people
caught time
Three and a half thousand years of engineering, from a stick casting a shadow to the caesium atom. Every article is built around a working mechanism you can play with and take apart.
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Water clock
Water drips at a steady rate, and the level tells the hour.
Read the article →Fire clock
Marked candles and Chinese trails of incense.
Read the article →Hourglass
It timed watches at sea and the length of sermons.
Read the article →Turret clock
A weight, a verge escapement, and a bell instead of a dial.
Read the article →Pendulum clock
Huygens makes the pendulum the regulator: from 15 minutes to 15 seconds a day.
Read the article →Marine chronometer
Harrison's H4 keeps time at sea and solves the longitude problem.
Read the article →Quartz clock
The first quartz clock filled a cabinet at Bell Labs: a crystal rings when driven by current.
Read the article →Atomic clock
Caesium: 9,192,631,770 periods, and by definition that is one second.
Read the article →Digital watch
LEDs, then liquid crystals: digits on the wrist and a battery that lasts seven years.
Read the article →A mechanism, not a picture
The drawings here are not drawn but computed. The sundial's shadow falls where the real Sun over Gandia would cast it, and the pendulum swings with the period Huygens's formula gives.
Hands on
Move the pointer over a drawing, press the arrow keys, take a mechanism apart. Everything the readout in a drawing's corner shows is computed live.
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A hobby project: no monetisation, just curiosity. Ten eras, ten articles, from the shadow of a gnomon to the caesium atom.