Hi everybody! Tomorrow my family and I are going to Hawaii on spring break! This, clearly, is totally awesome, but it means I can't post until two Thursdays from now. Sorry!
Okay, here's how the machine works:
First, a marble is pushed (up at the 'START' sign) and knocks down a few dominoes. The dominoes fall into a container, unbalancing the pulley system it's attracted to, and the other side of the pulley string nudges another marble. That marble knocks down some bigger dominoes and sets free the bird in its cage. The bird then flies over to the bird feeder, and the feeder, swaying from the collision with the bird, hits down yet another marble. The marble hits the scissors, cutting the string of the ballon, which releases another marble down below. The marble opens up the ant farm, and the ants march along to eat the slice of watermelon on the pulley. Once the ants have eaten enough, the pulley system will be unbalanced, and the other end will fall down, pushing the final marble onto the light switch.
Ah, the ever-intriguing complexities of Rube Goldberg machines.