airshaft vs lum

airshaft

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

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

lum

noun
  • A ventilating chimney over the shaft of a mine. 

  • A chimney; also, the top part of a chimney. 

  • A deep pool, especially one in a riverbed. 

  • A grove or wood; also, a woody valley. 

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