Filmmakers had to improvise because sound was not used in the cinema until almost 1930, and with that came genre conventions. In silent comedy, for obvious reasons, they used their body language to produce visual jokes rather than facial expressions and dialogue; those that were sound were not invented and close-ups at the time were very difficult to do. Because of this, many main personalities, such as Charlie Chaplin's hat and moustache or Buster Keaton's dead pan smile, adapted a distinctive prop to differentiate them. This is also why slapstick comedy, as well as Vaudeville, has become popular in silent comedy (in addition to the use of animals as props and an array of stunts and chases). Since Vaudeville was seen as the working class version of theatre, this greatly appealed to the mainstream working class audience. The use of mise-en-scene became important to the narratives, which appeared to be very simple and linear, because of these conventions. Many key figures of sil...