celluloid vs photoplay

celluloid

noun
  • The genre of cinema; film. 

  • Any of a variety of thermoplastics created from nitrocellulose and camphor, once used as photographic film. 

photoplay

noun
  • A theatrical play that has been filmed for showing as a movie. 

  • A novel adapted from a movie and illustrated with photographic stills taken from the film. Usage largely confined to the silent era of Hollywood. 

How often have the words celluloid and photoplay occurred in a corpus of books? (source: Google Ngram Viewer )