The striking in a clock is an extra part of the movement which operates bells or chimes.
If only the hour is struck, one extra weight or spring is required, with one extra winding hole. If the half and quarter hours are also struck, a second additional weight or spring is added, with a third winding hole.
The most popular chime, now known as the 'Westminster chime', is evolved from a phrase from the fifth bar of Handel's Messiah, 'I know that my redeemer liveth'. In about 1793, Revd Dr Joseph Jowett, Regius Professor of Civil Law at Cambridge University, is said to have consulted with Dr Randall, the Professor of Music, or from an undergraduate pupil, William Crotch, and between them they selected and evolved the chime used at Great St Mary's Church, Cambridge.
The tune was then adopted by Lord Grimthorpe, the designer of Big Ben. He remarked that it was strange that so many young men had listened to the chimes while at university but no attempt had been made to produce them elsewhere. The chime is known at Cambridge as 'Jowett's Jig'.