chimney vs chimney stack

chimney

noun
  • A vertical tube or hollow column used to emit environmentally polluting gaseous and solid matter (including but not limited to by-products of burning carbon- or hydrocarbon-based fuels); a flue. 

  • A narrow cleft in a rock face; a narrow vertical cave passage. 

  • A black eye; a shiner. 

  • The smokestack of a steam locomotive. 

  • The glass flue surrounding the flame of an oil lamp. 

  • A vagina. 

verb
  • To negotiate a chimney (narrow vertical cave passage) by pushing against the sides with back, feet, hands, etc. 

chimney stack

noun
  • A vertical structure, normally of brick, rising from a roof, containing one or more flues, each one terminating in a chimney pot. 

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