We use the word "clockwise" without a second thought. Tighten the lid clockwise. Stir the soup clockwise. But why do clock hands go that way in the first place? Couldn't they just as easily have gone the other direction?
The answer is the sundial. The first clocks with hands were built in the Northern Hemisphere, and they were made to work like the horizontal sundials people already knew. North of the equator, a sundial's shadow sweeps around in the same direction we now call clockwise. Clockmakers simply copied it.
Following the Shadow
A sundial is basically a flat plate with a pointer that casts a shadow. As the Sun appears to move across the sky, the shadow lines up with different hour marks. To stay accurate all year, the pointer's edge has to be parallel to Earth's axis, tilted at an angle equal to the local latitude.
In the Northern Hemisphere, the Sun travels from east to south to west over the day. A shadow always points the opposite way from the Sun, so on a flat, horizontal sundial, the shadow moves from west to north to east. Looking down at the dial, that's the familiar clockwise sweep. When mechanical clocks came along, their makers arranged the numbers and hands to match what people were used to seeing.
Before Clocks, It Was "Sunwise"
Before clocks were common, English speakers had other words for this direction. Clockwise motion was called "sunwise," or "deasil," a word from Scottish Gaelic tied to an old root meaning "right." The opposite direction had a wonderfully odd name: "widdershins," from an old German phrase meaning "against the direction."
Sundials have a very long head start. Along with water clocks, they are possibly the oldest timekeeping tools of all, so old that nobody knows exactly where or when they first appeared. Simple water clocks already existed in Babylon and Egypt by around the 16th century BC.
The early mechanical clocks of the 1200s didn't even have faces. They told time by ringing bells. In fact, the word clock comes from the medieval Latin word for bell, clocca.
Clocks That Run Backward
Not every clock follows the rule. A sundial mounted on a wall works differently. Its shadow moves counterclockwise, because the dial is turned on its side. Some clocks were built to mimic it, and the best-known surviving example is the astronomical clock in Münster, Germany, whose hands move counterclockwise.
In 18th-century Prague, a clock at the Jewish Town Hall was built to run counterclockwise, matching the right-to-left reading of Hebrew. And in 2014, under President Evo Morales, the clock outside Bolivia's legislature in La Paz was switched to run counterclockwise to promote indigenous values.
Clockwise Everywhere
Once clocks set the standard, the direction showed up all over daily life. Most nuts, screws, bolts, bottle caps, and jar lids tighten clockwise and loosen counterclockwise. One reason is that a right-handed person can twist more strongly when turning clockwise.
Here's one more twist. Whether something spins clockwise depends on where you're looking from. Earth's daily spin looks counterclockwise from above the North Pole, but clockwise from above the South Pole.
So the next time you check the time on the kitchen clock, you're really watching an echo of an ancient shadow, creeping across a sundial somewhere north of the equator. It's a small daily reminder that even our most modern habits can have very old roots.
