flush toilet vs john

flush toilet

noun
  • A toilet that uses water to flush urine and feces through a pipe to another location, typically a sewer main in urban settings or a septic tank elsewhere. 

john

noun
  • A device or place to urinate and defecate: now usually a toilet or lavatory, but also (dated) a chamber pot or outhouse. 

  • A male mule. 

  • A Western man traveling in East Asia. 

  • A prostitute's client. 

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