The ingenuity of toy manufacturers at the end of the 19th century and the beginning of the 20th century led to the creation of mechanisms that were capable of movement. Toys were no longer static, and seemed to come to life.
Gustav the miller and the little funicular railway move thanks to a counterweight system, whilst the mechanical clowns and animals have a simple pull cord mechanism.
Our gymnast dating back to 1918 appears to be sleeping until we place him on a heater: the heat radiated makes him begin his exercises.