IN 1920, THE POPULAR NEWSPAPER comic strip Jerry on the Job was adapted by Bray Studios into a few animated films. In “The Bomb Idea,” Jerry and another character read that “Bolsheviki” are on the loose throughout the country, and that all citizens should be on alert. Shortly after, a man arrives carrying a heavy, black sphere. Jerry and his friend panic, assuming the item is a bomb, when eventually it is revealed to just be a bowling ball. But it’s clear that by 1920, everyone knew what a bomb looked like.