About Clock of Ages
Clock of Ages: a free educational web toy with puzzles. Upon arrival, a plain clock tells your time. Beside it, a brass lift travels down fourteen floors, each an era of timekeeping history, where the clock becomes a clock of clocks.
The lift
Drag the brass knob down or up the lift, tap a floor, or use the arrow keys, to travel from now back to the stones that first framed the sun. Each floor is an era, a span of years, and there the clock’s twelve hours hold the twelve ways of telling time first found in them: the oldest at one o’clock, the newest at twelve.
The cases
Tap a timekeeper to open its case. Each holds its tale: where and when it was first made, and how long it stayed in use. Many also show the time where you are, counted their own way: in Babylonian double hours, by the sixty-day cycle, in Italian hours from the last sunset, or in the seconds of Unix time.
A gilt star marks an hour you can play: its case holds a toy and a challenge, such as making a sundial’s shadow say three in the afternoon, or a pendulum beat seconds. Solve one and its ring on the clock turns gold.
When something happened on today’s date in a floor’s years, its cases tell that too, from Wikipedia’s “On this day”.
The winding crown
The crown at twelve o’clock turns the clock’s finish: brass, silver, walnut, blacked steel and enamel blue. Gilt can’t be chosen, only earned: solve every challenge on the open floors and the whole clock turns gilt, and gilt joins the crown’s turn for good.
Five Clocks
A new puzzle every day, the same for everyone: five old clocks from five ages each show a time. Read each one, then set the plain clock to match. The closer you are, the more it scores, allowing for how precise each clock really was, and the clocks grow harder through the week. A new five arrive at midnight, your time.
When you’ve read all five, copy the share line to show how you did without giving the times away.
Timeline
If you’d rather see one at a time, the timeline puts every timekeeper in a single line, newest first, with the same tales and the same toys. Drag the knob down it, or use the arrow keys.
The timeline: every timekeeper, one at a time
Sound
Sound starts with your first tap. The speaker at the top right turns it off and on.
Where the history comes from
Every tale was checked against published sources before it went in: Wikipedia most often, and museums’ own records (the British Museum, Royal Museums Greenwich, Oxford’s History of Science Museum, the V&A and the German Clock Museum among them), journals, and old texts such as Vitruvius. Where historians still argue over a date or an inventor, the tale says so.
The live readings are worked out in your browser from your own clock, with the sun, moon and planets placed by the methods of Jean Meeus’s Astronomical Algorithms and E. M. Standish’s planetary elements at NASA JPL.
“On this day” comes from Wikipedia’s “On this day”, under CC BY-SA 4.0: one event for each year, roughly filtered, and kept as files on this site.
Found a mistake in a tale? Write to hello@clockofages.com.
What’s new
The clock keeps growing: more of its hours become toys. To hear when something new arrives (an occasional email, and nothing else): Get updates by email
The clock is free, with no ads, and kept wound by the people who enjoy it: Support.
Something you’d like it to do next? Suggest it.
Part of Cruxially
Clock of Ages is an educational web toy in Cruxially, a small, growing collection of educational web toys and puzzles. The same person makes and runs them all, and each one keeps its own site, terms and privacy page.
All the collection’s apps take payments through one Stripe account, so Stripe’s pages, your receipt and your card statement will reference Cruxially, not Clock of Ages.
v0.6.0 · November 3, 2026