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Change ringing is the art of ringing a set of tuned bells in a series of mathematical patterns called "changes". Change ringing differs from many other forms of campanology in that no attempt is made to produce a conventional melody; instead the bells are rung in a set of permutations. Today, change ringing can be found all over the world, performed in a variety of media, but it remains most popular in English churches, where it was developed in the 17th century. Such a church's bell tower typically contains a set of a few large church bells, known as a ring of bells, rigged to swing freely for slightly more than one revolution. The considerable inertias involved mean that each bell usually requires its own ringer and can only speak about once every two seconds—the time for a full revolution. Change ringing is also performed on handbells and on carillons (where the bells are fixed and the clappers are pulled over) though both of these instruments more commonly play melodies. ==Mechanics== Today some towers have as many as sixteen bells which can be rung together; six or eight bells are more common for the average church. The bell highest in pitch is known as the ''treble'' and the bell lowest in pitch the ''tenor''. For convenience, the bells are referred to by number, with the treble being number 1 and the other bells numbered by their pitch—2,3,4, etc.—sequentially down the scale. (This system often seems counterintuitive to musicians, who are used to a numbering which ascends along with pitch.) The bells are usually tuned to a diatonic major scale, with the tenor bell being the tonic (or key) note of the scale. Some towers contain additional bells which are used to allow different subsets of the full number to be rung, still to a diatonic scale. For instance, many 12-bell towers have a ''flat sixth'', which if rung instead of the normal number 6 bell allows 2 to 9 to be rung as light diatonic octave; other variations are also possible.〔(Dove entry for ) Worcester Cathedral, a twelve bell tower with 3 semi-tone bells. (Search on Dove's Guide for towers with 13 or more bells ), note that Christ Church Cathedral, Dublin is listed as having 16 bells, with additional sharp 6, 9 and 13; Swan Bells, Perth, Western Australia, is again a 16 but with additional flat 3 and 10. Retrieved 28 May 2008.〕 The bells in a tower reside in the ''bell chamber'' or ''belfry'' usually with louvred windows to enable the sound to escape. The bells are mounted within a ''bellframe'' of steel or wood. Each bell is suspended from a ''headstock'' fitted on trunnions (plain or non-friction bearings) mounted to the belfry framework so that the bell assembly may rotate. When stationary in the ''down'' position, the centre of mass of the bell and clapper will be appreciably below the centreline of the trunnion supports, thus giving a pendulous effect to the assembly and it is this dynamic which is controlled by the ringer's rope. The headstock is fitted with a wooden ''stay'' which, in conjunction with a ''slider'', limits maximum rotational movement to a little less than 370 degrees. To the headstock a large wooden wheel is fitted and to which a rope is attached; the rope wraps and unwraps as the bell rotates backwards and forwards. This is full circle ringing and quite different from fixed or limited motion bells which ''chime''. Within the bell the ''clapper'' is constrained to swing in the direction that the bell swings. The clapper is a rigid steel or wrought iron bar with a large ball to strike the bell. The thickest part of the mouth of bell is called the soundbow and it is against this that the ball strikes. Beyond the ball is a ''flight'' which controls the speed of the clapper. In very small bells this can be nearly as long as the rest of the clapper. Below the bell chamber there may be one or more sound chambers, (one of which is likely to house the clock mechanism if the church has one) and through which the rope will pass before it drops into the ''ringing chamber'' or room. Typically, the rope's length will be such that it falls close to or on to the floor of the ringing chamber. About from the floor, the rope will have a woollen grip called the ''sally'' (usually around long) while the lower end of the rope will be doubled over to form an easily held ''tail-end''. Unattended bells are normally left hanging in the normal ("down") position but prior to being rung, the bells will be ''rung up''. In the down position the bells are safe if a person touches them or pulls a rope. A bell which is up is dangerous to be near and only expert ringers should ever contemplate entering a bell chamber or touching a rope when the bells are up. The ringer pulls on the rope and starts the bell swinging. Each time the bell swings the ringer adds a little more energy to the system, similar to pushing a child's swing. Eventually there is enough energy for the bell to swing right up and be left over-centre just beyond the balance point with the stay resting against the slider. The bellringers typically stand in a circle around the ringing chamber, each managing one rope. Bells and their attendant ropes are so mounted that the ropes will be pulled in a circular sequence, usually clockwise, starting with the lightest (treble) bell and descending to the heaviest (tenor). To ring the bell, the ringer will first pull the sally towards the floor, upsetting the bell's balance and causing it to swing on its bearings. As the bell swings downwards the rope unwinds from the wheel and the ringer adds enough pull to counteract friction and air resistance. The bell winds the rope back onto the other side of the wheel as it rises and the ringer can slow (or ''check'') the rise of the bell if required. The rope is attached to one side of the wheel so that a different amount of rope is wound on and off as it swings to and fro. The first stroke is the ''handstroke'' with a small amount of rope on the wheel. The ringer pulls on the sally and when the bell swings up it draws up more rope onto the wheel and the sally rises to, or beyond, the ceiling. The ringer keeps hold of the tail-end of the rope to control the bell. After a controlled pause with the bell on or close to its balancing point, the ringer will ring the ''backstroke'' by pulling the tail-end, causing the bell to swing back towards its starting position. As the sally rises the ringer will catch it to pause the bell at its balance position. In English style ringing the bell is rung up such that the clapper is resting on the lower edge of the bell when the bell is on the stay. During each swing, the clapper travels faster than the bell, eventually striking the soundbow and making the bell sound. The bell ''speaks'' roughly when horizontal as it rises, thus projecting the sound outwards. The clapper rebounds very slightly, allowing the bell to ring. At the balance point the clapper will pass over the top and rest against the soundbow. In change ringing where the order in which the bells strike is constantly being altered, it is necessary to time the swing so that this strike occurs with precise positioning within the overall pattern. Precision of striking is important at all times. To ring quickly, the bell must not complete the full 360 degrees before swinging back in the opposite direction, while ringing slowly the ringer waits with the bell held at the balance, before allowing it to swing back. To achieve this, the ringer must work with the bell's momentum, applying just the right amount of effort during the pull that the bell swings as far as required and no further. This allows two adjacent bells to reverse positions; the quicker bell passing the slower bell to establish a new pattern. Although ringing up certainly involves some physical exertion, actual ringing should rely more on practised skill than mere brute force; after all, even the smallest bell to be encountered in a tower will be much heavier than the person ringing it. The heaviest bell hung for full-circle ringing is in Liverpool Cathedral and weighs .〔(【引用サイトリンク】title=history )〕 Despite this colossal weight, it can be safely rung by one (experienced) ringer. (Whilst heavier bells exist—for example Big Ben—they are generally only chimed, either by swinging the bell slightly or having the bell hung dead and using a mechanical hammer.) 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「change ringing」の詳細全文を読む スポンサード リンク
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