flue vs vas

flue

noun
  • In an organ flue pipe, the opening between the lower lip and the languet. 

  • A pipe or duct that carries gaseous combustion products away from the point of combustion (such as a furnace). 

  • An enclosed passageway in which to direct air or other gaseous current along. 

vas

noun
  • A vessel or duct transporting any bodily fluid, such as blood, lymph, chyle, or semen. 

  • The vas deferens. 

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