lenticle n. a glass window in a clock casing that displays the swinging lever, or bob, of the pendulum.
Today’s “There’s a Word for That?” comes down to us from the Latin. The root lenti means lens. The word lens itself (including its Latin root) is derived from the lentil seed, which has the shape of a biconvex lens – a lens with a convex curve on both sides; the most common lens type up until this century and the shape of the lens of a human eye. So it’s clear to see where lens got its name. This root also spawns related words, such as lenticular and lentiform, both which refer to a biconvex shape. If you want to refer to something as just simply lens-shaped (either convex, concave, or plano, or some combination of the preceding), you can use lentoid or phacoid to describe its shape.
Pendulums have been around for a long time and take their name from the Latin root pendulus meaning hanging or suspending, which pretty well sums up what a pendulum does. The French physicist, Jean Bernard Léon Foucault, took the pendulum one step further than its employment as a simple timing device, and used it to demonstrate the rotation of the earth, thereby getting the pendulum of this type named after him (he also named, but didn’t invent, the gyroscope).
Another interesting word contained in lenticle’s definition is bob. Bob has a number of varied definitions; the one used here pertains to its use as the terminal object of a suspended device. There are a number of visual images that spring to mind: the float on a fishing line, the plumb weight at the end of a plumb line, and the weight at the end of a kite tail – all are also known as bobs.
And as long as we’re on the subject of trivial clock words, I know you’ve seen clocks that have those mechanical figures that periodically move around noting the hour and quarter-hours; sometimes in very elaborate movements and spins. The little guy that strikes the bell is called a jack. Just thought you might want to know.