Mechanism and manufacture
Bells are the largest and loudest instrument in the world. The way they are hung is what makes English change ringing unique and so different to anywhere else in the world.
Bells are made from an alloy of copper and tin and are arranged in the tower down the musical scale from the smallest (called the 'treble') to the biggest ('tenor') which is the lowest note. The average tenor weight is 510kg, although they can weigh up to 4,200kg.
Bells are hung within a wooden or steel frame and attached to a wheel. They rotate around the centre of the wheel, with the 'clapper' in the centre striking the inside of the bell to sound.
The special feature of English bells is that they have a 'stay' which allows them to pause in an up-right position. This means the ringer can control when they strike by pulling them from this 'set' position to swing at the correct time.
Bell v Car
The average weight of a 'tenor' bell is similar to that of a small car.
Within the frame, the bells pivots on the gudgeon as it swings, while the clapper strikes the inside of the bell to make the noise. Although not shown in the video model, the rope wraps around the wheel as it is what the ringer below uses to control the bell's swing.
Bells are tuned to a particular note, despite actually producing a range of notes at the same time. Once cast, they are spun and metal slowly ground away from the inside. This process flattens the pitch of note the bell makes.
Bells have been made, or 'cast', in Britain for hundreds of years and, whilst being more refined, the process has changed little. Moulds are made of the bells before molten metal is poured in and left to cool. The bells are left to cool for several days, often in pits as has been done for centuries.