Keeping Time
“It’s the epicycloidal curve that governs the gears and gizmos that turn the hands of time,” Bob tells me. “No epicycloidal curve, no clock!”
The word epicycloidal is new to me. I like it. I like how it rolls off the tongue. Five cool syllables sliding along until the last final (-kloid’l), forces the tip of the tongue to the roof of the mouth, stopping where the roots of the two front teeth slip under the gum line; you don’t get that kind of lexical adventure every day. Go ahead. Try it! Ep-i-cy-cloid’al. What’s not to like about that? It’s fun to say.
The epicycloidal curve is the path that a point on the perimeter of a circle will travel when it rotates around the perimeter of another circle. When one gear rotates around another, the point on the rotating gear draws an invisible epicycloidal curve. And because it does, the hands of time make their journey around the face of a clock.
Point Rotating On A Curve
Curve Drawn Through The Rotating Point
