Bell

A bell is a directly struck idiophone percussion instrument. Most bells have the shape of a hollow cup that when struck vibrates in a single strong strike tone, with its sides forming an efficient resonator. The strike may be made by an internal "clapper" or "uvula", an external hammer, or—in small bells—by a small loose sphere enclosed within the body of the bell (jingle bell).

Bells are usually cast from bell metal (a type of bronze) for its resonant properties, but can also be made from other hard materials; this depends on the function. Some small bells such as ornamental bells or cow bells can be made from cast or pressed metal, glass or ceramic, but large bells such as church, clock and tower bells are normally cast from bell metal.

Bells intended to be heard over a wide area can range from a single bell hung in a turret or bell-gable, to a musical ensemble such as an English ring of bells, a carillon or a Russian zvon which are tuned to a common scale and installed in a bell tower. Many public or institutional buildings house bells, most commonly as clock bells to sound the hours and quarters.

Historically, bells have been associated with religious rites, and are still used to call communities together for religious services. Later, bells were made to commemorate important events or people and have been associated with the concepts of peace and freedom. The study of bells is called campanology.

History
The earliest archaeological evidence of bells dates from the 3rd millennium BC, and is traced to the Yangshao culture of Neolithic China. Clapper-bells made of pottery have been found in several archaeological sites. The pottery bells later developed into metal bells. In West Asia, the first bells appear in 1000 BC.

The earliest metal bells, with one found in the Taosi site and four in the Erlitou site, are dated to about 2000 BC. Early bells not only have an important role in generating metal sound, but arguably played a prominent cultural role. With the emergence of other kinds of bells during the Shang Dynasty (c. 1600 – c. 1050 BC), they were relegated to subservient functions; at Shang and Zhou sites, they are also found as part of the horse-and-chariot gear and as collar-bells of dogs.

The book of Exodus in the Bible notes that small gold bells were worn as ornaments on the hem of the robe of the high priest in Jerusalem. Among the ancient Greeks, hand bells were used in camps and garrisons and by patrols that went around to visit sentinals. Among the Romans, the hour of bathing was announced by a bell. They also used them in the home, as an ornament and emblem, and bells were placed around the necks of cattle and sheep so they could be found if they strayed.

See also Klang Bell (Malaysia, 2 c. BC) of the British Museum collection.

Styles of ringing
In the western world, the common form of bell is a church bell or town bell, which is hung within a tower or bell cote. Such bells are either fixed in a static position ("hung dead") or mounted on a beam (the "headstock") so they can swing to and fro. Bells that are hung dead are normally sounded by hitting the sound bow with a hammer or occasionally by pulling an internal clapper against the bell.

Where a bell is swung it can either be swung over a small arc by a rope and lever or by using a rope on a wheel to swing the bell higher. As the bell swings higher the sound is projected outwards rather than downwards. Larger bells may be swung using electric motors. In some places, such as Salzburg Cathedral the clappers are held against the sound bow whilst the bells are raised, then released sequentially to give a clean start to the ringing. At the end they are successively caught again by the mechanism to silence the bells.

Bells hung for full circle ringing are swung through just over a complete circle from mouth uppermost. A stay (the wooden pole seen sticking up when the bells are down) engages a mechanism to allow the bell to rest just past its balance point. The rope is attached to one side of a wheel so that a different amount of rope is wound on and off as it swings to and fro. The bells are controlled by ringers (one to a bell) in a chamber below, who rotate the bell to through a full circle and back, and control the speed of oscillation when the bell is mouth upwards at the balance-point, when little effort is required.

Swinging bells are sounded by an internal clapper. The clapper may have a longer period of swing than the bell. In this case the bell will catch up with the clapper and if rung to or near full circle will carry the clapper up on the bell's trailing side. Alternatively, the clapper may have a shorter period and catch up with the bell's leading side, travel up with the bell coming to rest on the downhill side. This latter method is used in English style full circle ringing.

Occasionally the clappers have leather pads (called muffles) strapped around them to quieten the bells when practice ringing to avoid annoying the neighbourhood. Also at funerals, half-muffles are often used to give a full open sound on one round, and a muffled sound on the alternate round – a distinctive, mournful effect. This was done at the Funeral of Diana, Princess of Wales in 1997.

A carillon, which is a musical instrument consisting of at least 23 cast bronze cup-shaped bells, is tuned so that the bells can be played serially to produce a melody, or sounded together to play a chord. A traditional carillon is played by striking a baton keyboard with the fists, and by pressing the keys of a pedal keyboard with the feet. The keys mechanically activate levers and wires that connect to metal clappers that strike the inside of the bells, allowing the performer to vary the intensity of the note according to the force applied to the key.
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https://en.wikipedia.org/wiki/Bell