In campanology (bell ringing), a peal is the special name given to a specific type of performance of change ringing which meets certain exacting conditions for duration, complexity and quality. The definition of a peal has changed considerably over the years and its standardisation was one of the motivating factors in the formation of the Central Council of Church Bell Ringers in 1891. Currently, for a performance to be recognised as a peal by the Central Council it must consist of sufficient numerical sequences, or "changes" (at least 5,040 changes on up to seven working bells or 5,000 changes on higher numbers), meet a number of other criteria (collectively referred to as the decisions), and be published in The Ringing World. On typical tower bells a peal takes around three hours to ring; the time depends on several factors including the number of changes and the weight of the bells, which affects the speed of ringing. In addition to ordinary peals, ringers often ring quarter-peals, which are a quarter of the length of a full peal, making them easier to ring as most quarter-peals take around 45 minutes to complete. A ring of English-style full-circle bells is sometimes referred to as a peal of bells. Historic meaning Originally a peal referred to a sequence of changes of any length, now often referred to as a touch. A touch being more than a plain course, but not a quarter or full peal. However, the original meaning is still in use today in call-change ringing. The most famous and frequently rung call-change peal, associated with the Devon Association of ringers, is named 60 on 3rds. Following the invention of the ringing method known as Grandsire Doubles, the term peal or "full peal" was applied to the ringing of sequences including each possible permutation of the set of bells exactly once. On five bells (Doubles), there are 120 permutations taking about four minutes to ring on tower bells. This is arrived at by the calculation 1 × 2 × 3 × 4 × 5 = 5! = 120 unique permutations. These figures rapidly increase as more bells are added. With the standardisation of the term "peal", ringing all possible permutations is referred to as the "extent". For seven bells the extent is 7! = 5,040 changes and is thus synonymous with a peal. For lower numbers of bells several extents are rung to