The grandfather clock is a traditional design icon and the build of these clocks stems from the time when a mechanical movement coupled with a long heavy pendulum made for the most accurate domestic time-piece available. The first pendulum clock was developed in 1656 and relies on very simple principles to produce a remarkably accurate time piece. Previous spring based designs made for some pretty inaccurate time pieces. In the eighteenth century the antique grandfather clock design now so familiar became very popular.