Why clocks turn clockwise
No law of nature says clock hands must turn to the right. The most likely reason they do is a shadow, and the part of the world where the first clocks were made.
No law of nature says clock hands must turn to the right. The most likely reason they do is a shadow, and the part of the world where the first clocks were made.
It is such a basic rule that we rarely notice it. “Clockwise” is even the word we use to describe the direction. But the word came after the clock, so the real question is why the clock went that way in the first place.
The sundial came first#
Long before mechanical clocks, people told the time with sundials: a flat plate with an upright piece, called a gnomon, that casts a shadow. Sundials are very old, with the earliest dating back to around 1500 BC in Egyptian and Babylonian astronomy.
In the northern half of the world, a sundial’s shadow moves in one particular direction over the day. It sweeps from the west side, past the north side, to the east side. Seen from above, that is clockwise.
The clock copies the shadow#
Mechanical clocks appeared in Europe around the start of the 14th century. They were new machines, and the people who built them had no rule to follow. What they did have was a lifetime of reading time from sundials.
The explanation most often given is that they copied what was familiar. If time had always moved one way on a sundial, a clock face that moved the same way would feel right, and it would be easy to check against the sundial in the town square.
It is worth being honest that this is an argument, not a documented fact. As one writer puts it, it cannot be proved, but it makes sense. Nobody has found a clockmaker’s note saying “we chose clockwise because of sundials”.
A question of geography#
There is a second part to the answer. Clockmaking developed almost entirely in the northern half of the world, so the northern shadow became the standard. A sundial placed in the southern half would cast a shadow that moves the other way.
If the first mechanical clocks had been built in, say, Australia, our hands might turn the other way, and we would call it clockwise anyway.
The exceptions#
Clocks that run backwards do exist. A well-known example is the clock in the cathedral of Florence, which is often cited as running anticlockwise, and there is a clock with Hebrew letters on the Jewish Town Hall in Prague that does the same. In 2014, a clock on the national congress building in La Paz, Bolivia, was changed to run anticlockwise, with the government linking the change to the country’s identity.
What to take from it#
Many conventions we think of as natural began as someone copying what they already knew. After enough copies, the choice was no longer a choice. It became the way things are done, and the people who might have done it differently were not asked.
The next time something seems to have only one possible form, it is worth asking where the first one was made, and who it was copying.
Sources#
- Curious Questions: Why do clocks go clockwise? Country Life. https://www.countrylife.co.uk/luxury/curious-questions-why-do-clocks-go-clockwise-213343
- Why Clocks Run Clockwise. Today I Found Out. https://www.todayifoundout.com/index.php/2016/06/clocks-run-clockwise/