What is a bell?
By definition, a bell is a semi-enclosed hollow vessel usually of metal, but sometimes of horn, wood, glass, or clay, struck near the rim either by an interior clapper or an exterior hammer or mallet to produce a ringing sound.
Bells may be categorized broadly as percussion instruments, and more specifically as idiophones that is, as instruments that sound by the vibration of resonant solid material. Their shape depends on cultural factors, intended use, and material of construction.
The walls vary from straight to convex, concave, hemispherical, barrel shaped (as in East Asia). All Western tower bells are tulip shaped.
In cross section they may be round, square, rectangular, elliptical, or many-sided. Chinese bells often have lotus-shaped rims.
The strongest sound-producing vibrations of bells occur near the rim (in Western bells, in the sound bow), in contrast to hollow gongs, where the vibrations are strongest in the centre.
The acoustical structure of bell sound is complex and has been completely understood only in modern times.
All bells contain an array of partials, or sound-wave frequencies of various pitches, but the tone of a musical bell consists of both harmonious partials and higher inharmonious partials.
Western bells are invariably rung by a metal striker; Asian bells, except for metal-clappered hand and wind bells, are normally struck by a wooden hand mallet or swinging horizontal beam that engages the exterior wall. Asian bells are also devoid of the sound bow and never swing. Russian bells are classed as Western bells (and are such by origin), but they are similar to Asian bells in that they remain stationary and are struck by manipulating the (internal) striker.
Bells are widely distributed geographically and usually possess a clearly defined cultural status everywhere where they are found. Legends surround them. Beliefs abound concerning their special powers to induce rain or to dissolve storm clouds; to thwart demons when worn as amulets or when placed on animals, buildings, or conveyances; or to invoke curses and lift spells. The concept of their purifying action is ancient, as is their use in ritual, especially in the religions of eastern and southern Asia. The Chinese rang bells to communicate with spirits.
In Russian Orthodoxy, bells have an iconographic and hence a liturgical and evangelical function. For similar reasons, Asian peoples and Russians both cast huge bells, to lend greater solemnity and authority to their utterance.
In both Buddhism and Christianity, bells are consecrated before being used liturgically.
In the Buddhist tradition, the first sound that a bell makes when struck signifies the awakened state which sees clearly into the nature of reality, and the fading tone is considered to be an icon of that reality, insofar as it symbolizes both awakening and impermanence. Thus the clear, brilliant sound of the bell symbolizes the emptiness, and therefore the openness of reality. Small handbells such as the one shown to the right are made of a blend of metals, and are used in tantric music. The bell is used as a sonic focus for meditation, a cadence factor for mantra recitation, and so forth. The sound of the bell is an apt symbol of the impermanence of all things.
The vajra- or thunderbolt-bell has a half-vajra as its handle and symbolizes the ultimate wisdom that is the source of, and always complements, universal compassion. Ringing the bell prefigures the joyful and compassionate teaching that flows spontaneously from perfect wisdom.
In Roman Catholicism, bells have symbolized paradise and the voice of God. Among the most basic and widespread uses of bells is signalling calling to worship, marking significant points of ritual, tolling the hours, announcing events, rejoicing, warning, mourning, and sounding alarms. But in the Christian tradition, a bell is so much more than simply a signal it is considered to be part of the Church's prayer itself, one of the architectonic and public dimensions of liturgy.
In Christian and Asiatic Buddhist monasteries, bells regulate daily routine, and medieval and Christian bells were named according to purpose: squilla for the refectory, nola for the choir, and so forth.
Bells have also been treasured as patriotic symbols and war trophies, and invaders quickly silenced those of the conquered in order to eliminate the most vivid symbol of resistance. Most cultures have made bells into artistic objects, with respect to shape, material, and ornamentation, and both Eastern and Western religions have incorporated symbolic motifs in the ornamentation of bells.
The ancient Chinese were the first to employ sequences of bells musically; such sequences are termed chimes, or pien chung. In the West since the 9th century, small sets of bells (chimes) in stationary suspension and generally tuned diatonically (to the seven-note scale) have been common (see bell chime).
Sets of tuned bells numbering at least 23 are termed carillons. Groups of two or more free-swinging bells are known as a peal; a single stationary bell in slow repetition a toll. All today may be operated electrically.
Change ringing is a British form of pealing whereby 5 to 12 swinging bells are rung in mathematical permutations. Working in teams, the ringers pause their bells at the top of their swing just long enough to let the next bell drop first. With skill, the sequences can become very complex, as can be seen in the diagram to the right.
The zvon of the Russian Orthodox Church makes use of both improvisational and repetitious rhythmic patterns, and is a highly developed form of public music.
Sets of handbells ranging up to five octaves have been popular in England and the US since the 19th century as a group method for producing melodies and simple harmonies.
In the main the liturgical and utilitarian functions of bells have greatly diminished, whereas their musical usage has increased in modern society.
The manufacture of bells
Forged and riveted metal bells antedate those of cast metal. European bell making was originally a monastic craft. The earliest Christian bells were of iron plates hammered square and riveted (resembling cowbells).
The earliest bell founding (i.e., the casting of bells from molten metal) is associated with the Bronze Age.
The ancient Chinese were superb founders, their craft reaching an apex during the Chou dynasty (c. 1122-221 BC). Characteristic were elliptical temple bells with exquisite symbolic decorations cast onto their surfaces by the cire perdue, or lost wax, process.
Although bronze casting was practiced in pre-Christian Europe, it was not resumed to any extent until the 8th century.
In bell founding, molten metal (usually bronze) is poured into a mold consisting of an inner core and outer mold or cope contoured to a bell's profile. Most molds are faced with loam, those for handbells with sand. The liquid metal, heated to about 1,100 degrees C (2,000 degrees F) enters a hole at the top while being tamped (driven by a series of light blows) down through another. To avoid undesirable porosity, gases formed are allowed to escape. Cooling is carefully controlled to prevent the outer surface from cooling faster than the inner, thereby setting up a tension leading to later cracking. Large bells require a week or two to cool.
When the mold is removed the rough casting of the bell is sandblasted and polished. If a certain pitch is required, small amounts of metal are removed from the bell's inner wall as it revolves on a milling table or lathe.
Bell metal, or bronze, is an alloy of copper and tin. Tin content may range from 13 percent in weight to 25 percent, rarely more. Tin increases brittleness, and large bells contain less than small ones do. Most carillon bells contain 20 percent.
Casting produced better toned bells by permitting greater wall thickness and more precise control of contour (now round). For centuries bells had a convex wall of uniform thickness, a shape termed a beehive or primitive bell. The wall was elongated for use in bell towers, and the rim was reinforced for more resonance and strength.
Pitch was successfully controlled by the 9th century, when tuned sets of small bells (called cymbala) appeared. By the 11th century, secular bell founders--often itinerant--were active, becoming dominant by the Renaissance.
The lofty towers of Gothic architecture led to much larger, more resonant bells and gave rise to an archaic version of the present campaniform bell: tulip-shaped with a narrow, rounded top; a long, straight waist spreading outward at the bottom; and a flared mouth, or sound bow. By the 13th century this shape predominated. Until the 15th century, when a shape similar to the modern Western one emerged, it was slowly transformed, the waist becoming proportionately shorter and concave, the top broader, the shoulder squared, and the sound bow thickened.
Bell founding attained considerable prestige, and the introduction of gunpowder in the 14th century added cannon making to the founder's output.
The founders of Belgium and the Netherlands surpassed all others, their stature growing as the carillon spread in that area in the 15th-18th century, their craft culminating with the 17th-century Dutch founders Fran?ois and Pierre H?mony.
The craft declined in the 19th century, particularly in the ability to tune accurately, but regained its excellence by the 20th.
Russian bell founding dates from the 13th century, and by the 16th, bells weighing many tons were made. The world's largest bell, the Tsar Kolokol III (Tsar Bell III) in Moscow, was cast in 1733-35, weighing about 400,000 pounds (180,000 kilograms); broken by fire in 1737, it never rang.
English founders traditionally paid little attention to their bells' inner tuning of the partials, because their bell usages--change ringing and chimes--did not involve harmony. In the 20th century they adopted the partial tuning used in Belgium and The Netherlands.
The pellet bell, or crotal (a term also having many other meanings), a spherical vessel with loose pellets, has been historically regarded as a type of bell, but modern authorities now classify it as a rattle; jingle and sleigh bells are familiar examples. Of great antiquity, it shares many of the ritual and magical functions of bells.