In particular, it is common to collect together a set of tuned bells and treat the whole as one musical instrument. Such collections — such as a Flemish carillon, a Russian zvon, or a British "ring of bells" used for change ringing — have their own practices and challenges; and campanology is likewise the study of perfecting such instruments, composing music for them, and performing it.
In this sense, however, the word "campanology" is most often used in reference to relatively large bells, often hung in a tower. It is not usually applied to assemblages of smaller bells, such as a glockenspiel, a collection of tubular bells, or an Indonesian gamelan.
The instrument is played sitting on a bench by hitting the top keyboard that allows expression through variation of touch, with the underside of the half-clenched fists, and the bottom keyboard with the feet, since the lower notes in particular require more physical strength than an organ, the latter not attaining the tonal range of the better carillons: for some of these, their bell producing the lowest tone, the 'bourdon', may weigh well over 8 tonnes; other fine ones settle for 5 to 6 tonnes. A carillon renders at least two octaves for which it needs 23 bells, though the finest have 47 to 56 bells or extravagantly even more, arranged in chromatic sequence, so tuned as to produce concordant harmony when many bells are sounded together.
The oldest are found in church towers in continental northern Europe, especially in cathedral towers in northern France and Belgium, where some (like the St. Rumbolds Tower in Mechelen, the Cathedral of Our Lady in Antwerp) became UNESCO World Heritage Sites – classified, rather misleadingly, with the Belfry of Bruges and its municipal Carillon under 'Belfries of Belgium and France'.
The carillon of Kirk in the Hills, Bloomfield Hills, Michigan, United States, has the highest number of bells in the world: 77.
Modern large carillon edifices have been erected as stand-alone instruments across the world, for instance the Netherlands Carillon at Arlington National Cemetery.
The Russian Tsar Bell is the largest extant bell in the world.
In England the bells in church towers are generally hung for full circle ringing: every bell swings through a complete circle (actually a little more than 360 degrees) each time it sounds. Between strokes, it sits poised 'upside-down', with the mouth pointed upwards; pulling on a rope connected to the bell swings it down and its own momentum swings it back up again on the other side.
These rings of bells have relatively few bells, compared with a carillon; six or eight-bell towers are common, with the largest rings in numbering up to sixteen bells. The bells are usually tuned to fall in a diatonic scale without chromatic notes; they are traditionally numbered from the top downwards so that the highest bell (called the treble) is numbered 1 and the lowest bell (the tenor) has the highest number; it is usually the tonic note of the bells' scale.
To swing the heavy bells requires a ringer for each bell. Furthermore, the great inertias involved mean that the ringers have only a limited ability to retard or accelerate their bells' cycle. Along with the relatively limited palette of notes available, the upshot is that such rings of bells do not easily lend themselves to ringing melodies.
Instead, a system of change ringing evolved which centres on mathematical permutations. The ringers begin with rounds, which is simply ringing down the scale in order. (On six bells this would be 123456.) The ringing then proceeds in a series of rows or changes, each of which is some permutation of rounds (for example 214356).
In call change ringing, one of the ringers (known as the conductor) calls out to tell the other ringers how to vary their order from row to row. Some ringers practice call changes exclusively; but for others, the essence of change ringing is method ringing.
In method or scientific ringing each ringer has memorized a pattern describing his or her bell's course from row to row; taken together, these patterns (along with only occasional calls made by a conductor) form an algorithm which cycles through the various available permutations.
Serious ringing always starts and ends with rounds; and it must always be true — each row must be unique, never repeated. A performance of a few hundred rows or so is called a touch; approximately five thousand rows make a peal (which takes about three hours to ring). A performance of all the possible permutations possible on a set of bells is called an extent; with bells there are ! possible permutations. Since 7!=5040, an extent on seven bells is a peal; 8!=40,320 and an extent on eight bells has only been accomplished once, taking nearly nineteen hours.
Ringing in English belltowers become a popular hobby in the late 17th century, in the Restoration era; the scientific approach which led to modern method ringing can be traced to two books of that era, Tintinnalogia or the Art of Ringing (published in 1668 by Richard Duckworth and Fabian Stedman) and Campanalogia (also by Stedman; first released 1677; see Bibliography). Today change ringing remains most popular in England but is practiced worldwide; over four thousand peals are rung each year.
Dorothy Sayers' mystery story, "The Nine Tailors" (1934) centers around change ringing of bells in a church in Essex.