Big Ben vs sundial

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. 

sundial

noun
  • A device measuring the time of day by the position of a shadow cast by a pole or plate (gnomon) upon an engraved series of marks. 

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