A chain reaction occurs when one action causes one or more additional actions. An example is pushing the first of many aligned dominoes, causing successive dominoes to be pushed over. Eventually, all dominoes will be pushed over, if aligned within a close enough proximity.
In Rube Goldberg’s “Self-Operating Napkin”, the chain reaction begins when the soup spoon (A) is raised to “Professor Butts’ ” mouth, pulling string (B) and thereby jerking ladle (C), which throws the cracker (D) past the parrot (E). The parrot jumps after the cracker, causing the perch (F) to tilt, upsetting seeds (G) into the pail (H). The extra weight in the pail pulls a cord (I), which opens and lights an automatic cigar lighter (J), setting off the rocket (K), which causes the sickle (L) to cut the string (M) and allows the pendulum with the attached napkin to swing back and forth, wiping Professor Butts’ chin. Task completed!
