Why Do the Hands on a Clock Move Clockwise?

Clocks run clockwise, like this one, and even counter-wise.

"Why" questions are not only some of the most interesting to ask, they are often some of the hardest to answer. One of these (asked in a popular book by David Feldman) is why clocks run clockwise. There are two answers, the first deriving from a play on words, the other, more serious answer, deriving from the history of time telling.

Clockwise

The simplest answer to the question of why the hands of a clock move clockwise is because the word clockwise was coined to describe the motion of the hands of the clock. Even if the hands of a clock moved in the opposite direction, provided they had always done this, this is the direction that would be called clockwise. But, for a more serious answer, you have to look at the history of time telling.

Sun Dials

Prior to the invention of mechanical clocks, time was told by tracking the movement of the sun, moon and stars through the sky. Sun dials tracked the movement of the sun and indicated the time during the day. These simple devices contained an erect tab in the middle of a circle and, depending on the position of the shadow, the time of day could be known. In the Northern hemisphere, the shadow of the sun on a sundial moves in the direction we now call clockwise.

Mechanical Clocks

Though clocklike devices have appeared in various cultures around the world, modern clocks trace their lineage most directly to an invention by Christiaan Huygens of Hague, Netherlands in 1602. Since Hague is in Europe, and Europe is in the Northern hemisphere, when the first mechanical clocks were made, they preserved the same basic operation as a sundial in the Northern hemisphere. Only instead of a shadow moving across the dial in a clockwise direction, metallic hands driven by springs and pendulums were used instead.

Reverse Clocks

If the arbitrary nature of the selection of which direction counts as clockwise is an annoyance to you, you can make a bold statement by purchasing a reverse clock in which the hands move in a counter-clockwise direction -- with numbers adjusted to suit.

References

• "Smithsonian Astrophysical Observatory - Harvard University"; Eyes on the Sky, Feet on the Ground"; Dr. Christine Jones et al.
• Antique Clocks: Who Invented the Clock?
• Trinity College Dublin: Christiaan Huygens

Resources

• The Backwards Clock