exploration vs operating theatre

exploration

noun
  • A physical examination of a patient. 

  • The process of exploring. 

  • The (pre-)mining process of finding and determining commercially viable ore deposits (after prospecting), also called mineral exploration. 

  • The process of penetrating, or ranging over for purposes of (especially geographical) discovery. 

operating theatre

noun
  • A room in a hospital used for performing surgery (originally designed for operations in front of observers). 

How often have the words exploration and operating theatre occurred in a corpus of books? (source: Google Ngram Viewer )