Campanology Word of the Day: Clapper

A violin is a lovely instrument, but to hear its vibrating soul, it must be played with a rosined bow. A marimba, that most percussive of keyboards, cannot sound without at least one mallet. So too is a bell reliant upon a striking agent: the clapper.

The clapper hangs inside a bell, swinging back and forth to make a bell ring. A clapper is composed of a metal shaft terminating in a solid sphere. It is this sphere that strikes the inner sound bow to send reverberations throughout the bell – giving us those rich, resonant tones.

The bell’s clapper may be made of various metals or alloys, but often they are bronze or cast iron. A cast iron clapper tends to lend a rounder resonance over a bronze one, which may offer a brighter or sharper tone. A clapper pin of stainless steel connects the clapper to the bell, pinioning it to the top-center inside the bell, just under the canons. This also serves as the axle upon which the clapper swings.

The bells of the Giralda bell tower at the Cathedral of Saint Mary of the See in Seville, Spain

Image: The bells of the Giralda bell tower at the Cathedral of Saint Mary of the See in Seville, Spain, show two types of clappers: one that is free hanging and makes contact when the bell is swung (left) and one that is pulled against the side of the bell with a mechanical cable.

Some bells have clapper springs, an optional internally-mounted component that keeps the clapper from hitting the bell with its full force. This can be a good feature for older cast iron bells, which may be more susceptible to cracks. A clapper spring also prevents the clapper from resting or bouncing on the bell, so you hear a single pure strike instead of a double-tap each time it is rung.

Clappers and their associated hardware sustain routine impact, so they tend to be one of the bell components most often needing replacement or repair. When an old bell is rehung in a bell tower with a new clapper, a bell founder might recommend rotating the bell a quarter turn from its original position, ensuring the clapper hits a less-stressed area of the bell to prevent any cracks from developing.

Bells within St. Michael's Golden-Domed Monastery in Kyiv, Ukraine

Image: A view of the bells and bell clappers within the belfry of St. Michael's Golden-Domed Monastery in Kyiv, Ukraine.

Not all bells rely upon internal clappers to ring. Some bells, like those comprising carillons and chimes, might use an intricate system of external hammers to tap the bell and cause it to ring. Bells of Asian origin are often struck by an external mallet or swinging wooden beam. Do we have a preference? Not at all! We just love to hear those bells ring.