These clocks are working without a pendulum. Instead of the pendulum a ball is rolling down an inclined plane, for which it takes 20 seconds. Then the Seesaw tends to the opposite direction and the process begins again.
This clock type is relatively unknown although the first examples were built in the 17th century. Serpina was inspired by the design of Sir William Congreve from the early 19th century.
Rolling ball clocks are primarily great entertainers. Although Galileo Galilei already discovers, that a ball needs on an inclined plane always the same time for the same distance. In practice, however, all rolling ball clocks have a problem with the accuracy, because dust on the seesaw destroys the theory.
"Dust on the seesaw destroys the theory."