Big Ben vs chronometer

Big Ben

name
  • The hour bell in the Elizabeth Tower (formerly known as the Clock Tower), adjacent to the Houses of Parliament in Westminster, London, United Kingdom. 

  • The clock tower itself. 

chronometer

noun
  • A device for measuring time, such as a watch or clock. 

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