Kosin store wooden wall clocks

The thirteenth and final video in this series introduces the pendulum and its suspension and concludes with footage of the regulator shortly after completion (except for polishing and casing) in 2005. The pendulum suspension consists of a thin, flexible steel ribbon (the 'suspension spring'), just over 9 cm in length, connecting the pendulum hook to an upper mounting point. The mounting point is, in turn, firmly attached to a solid wall. Harrison's unique form of 'suspension cheeks' are positioned to either side of the suspension spring and are adjusted laterally, in order to securely contact the sides of the spring near its upper end. The surfaces of the cheeks to either side of the spring are formed as arcs of circles*. The pendulum is attached to the lower end of the suspension spring via the hook, which engages with a pivot pin at the top of the pendulum. By way of a considerably abbreviated and simplified explanation, as the pendulum swings, the spring is obliged to flex and conform to the shape of whichever cheek is closest at any given time. The effect is to hasten the natural swing of the pendulum, in order to compensate for an inherent deficiency, called 'circular error'. By altering the radius of the active cheek faces, the degree of compensation may be adjusted to perfection. The pendulum itself consists of nine metal rods and a 'bob' at the lower end. This arrangement is popularly known as Harrison's 'gridiron' pendulum, because of its appearance. In ...