chamber pot vs flush toilet

chamber pot

noun
  • A container used for urination and defecation, particularly those used in early modern towns before the advent of the flush toilet. 

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. 

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