Bells are a feature of ceremony and ritual. They are used for meditation and prayer, and to mark significant life events such as funerals and weddings. Bells are used to mark out the timetable of our daily lives – appearing as alarm bells, warning signals and in mechanized chimes in clocks.

In Japan, bonsho temple bells are rung 108 times at the end of the old year to banish worldly cares and sin. Public buildings also are decorated with hanging bells like the 13,760-kg (131⁄2-ton) hour bell known as ‘Big Ben’ in the tower that forms part of the Houses of Parliament in London.

Construction

Bells can be made from wood, stone, glass or terracotta, although metal is the most common material. They are usually cast in bronze. In shape they range from spherical or crotal bells, through shallow mushroom shapes, to the classic church bell with a flared lip.

The shape of the bell influences its timbre. Bells that are uniform in cross-section along their body, like Japanese and Chinese temple bells (bianzhong), have a slow attack but a long decay, which can make the sound travel a great distance. A cone-shaped bell with an exaggerated lip, like a western church bell, has a very strong attack and a brazen sound. True bells are tuned to a specific pitch.

Bell-Casting

Bells have been used in Southeast Asia since 2000 BC, and the Chinese are believed to have developed the technique of bell-casting. A metal bell is cast in a mould formed from a cope (the outer skin of the bell) and a core (the inner skin). In pre-industrialized times, bells were made from a wax model, which was coated with layers of clay loam and baked in a bell pit, allowing the wax to melt and drain away, leaving a mould in baked clay into which the heated liquid-bell metal was cast. Once the metal has set cold, the bell is tuned by rotating it on a turntable, mouth upwards, and shaving small amounts of metal off the inside walls of the bell. It is then cleaned and polished.

Pitch and Tuning

A bell has five principal elements to its sound. The ‘hum tone’ is the lowest pitched overtone and lasts the longest when the bell is struck. An octave above the hum tone is the prime note, the most prominent pitch heard when the bell is struck. Three further overtones – the tierce, quint and nominal – sound a minor third, a perfect fifth and an octave respectively above the prime. Once tuned at the foundry, a bell needs no further tuning, and provided it is not damaged it will retain its tuning indefinitely.

Different musical cultures prefer bells tuned in different ways. Russian bells, for example, are cast to sound a particular pitch, but they do not have fine adjustments made to their tuning as is common with European bells. Ancient Chinese bells were constructed to play two pitches. Striking the bell...

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