airshaft vs chimney stack

airshaft

noun
  • A vertical (or near vertical) opening (shaft) running from a courtyard to the sky, thus allowing air to circulate to high-rise apartments or offices. 

  • A passage supplying ventilation into a mine tunnel or other underground facility. 

  • A device used for handling winding reels in the processing of web-fed materials, such as in continuous-process printing presses. 

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 airshaft and chimney stack occurred in a corpus of books? (source: Google Ngram Viewer )