photoplay vs seventh art

photoplay

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

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

seventh art

noun
  • Chiefly preceded by the: the art of making motion pictures; filmmaking. 

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