Part of a grandfather clock can include the PENDULUM, which is an apparatus consisting of a weighted rod suspended from a pivot so that it can swing freely back and forth. The PENDULUM is used to regulate the movement of the clock's hands. Another part of a grandfather clock is the GONG, which is a percussion instrument made of metal or stone that produces a ringing sound when struck. Finally, the hourhand is the hand on a clock that indicates the hour. It is usually the shorter of the two hands on a clock face.