page_title: Change ringing
section_title: Technique and physics
hierarchical_section_title: Change ringing / Technique and physics
caption_attribution_description: English: The eight bells of St Bees Priory, Cumbria, shown in the "up" position, in which they are normally left during rests in a ringing session. When being rung they swing through a full circle from mouth upwards round to mouth upwards, and then swing back again. They are controlled by ropes on full-circle wheels. This method of ringing is know as "English full-circle bell ringing". Bells cast in 1857 by Charles and George Mears of Whitechapel.
context_page_description: Change ringing is the art of ringing a set of tuned bells in a tightly controlled manner to produce precise variations in their successive striking sequences, known as "changes". This can be by method ringing in which the ringers commit to memory the rules for generating each change, or by call changes, where the ringers are instructed how to generate each change by instructions from a conductor. This creates a form of bell music which cannot be discerned as a conventional melody, but is a series of mathematical sequences.
  Change ringing originated following the invention of English full-circle tower bell ringing in the early 17th century, when bell ringers found that swinging a bell through a much larger arc than that required for swing-chiming gave control over the time between successive strikes of the clapper. Ordinarily a bell will swing through a small arc only at a set speed governed by its size and shape in the nature of a simple pendulum, but by swinging through a larger arc approaching a full circle, control of the strike interval can be exercised by the ringer.
context_section_description: Today, some towers have as many as sixteen bells that can be rung together, though six or eight bells are more common. The highest pitch bell is known as the treble, and the lowest is 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 counter-intuitive to musicians, who are used to a numbering that ascends 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 so that different subsets of the full number can 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.
  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 can rotate. When stationary in the down position, the centre of mass of the bell and clapper is appreciably below the centreline of the trunnion supports, giving a pendulous effect to the assembly, and this dynamic 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 passes before it drops into the ringing chamber or room. Typically, the rope's length is such that it falls close to or on to the floor of the ringing chamber. About 5 feet (1.5 m) from the floor, the rope has a woolen grip called the sally (usually around 4 feet (1.2 m) long) while the lower end of the rope is 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 are rung up. In the down position, the bells are safe if a person touches them or pulls a rope. A bell that 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.
  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 are 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 first pulls the sally towards the floor, upsetting the bell's balance and swinging it 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
caption: The bells of St Bees Priory shown in the "up" position. When being rung they swing through a full circle from mouth upwards round to mouth upwards, and then back again.
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