nder a common approximation of pendulum motion, the period of a pendulum depends only upon the length of the pendulum and the acceleration of gravity. The pendulum system in this demo comprises 24 pendulums with lengths chosen so that each pendulum completes a different integral number of oscillations during a 60 second "system period". The number of oscillations of the pendulums during the system period lie among the 24 integers in the range [68, 91]: the longest pendulum completes 68 oscillations while the shortest one completes 91. When the pendulums are released from rest at a common initial angle, wave patterns emerge in their motion. These patterns are most evident when the system is viewed from the side or top.