conduit vs inner tube

conduit

noun
  • A duct or tube into which electrical cables may be pulled; a type of raceway. 

  • A pipe or channel for conveying water, etc. 

  • A means by which something is transmitted. 

  • An investment vehicle that issues short-term commercial paper to finance long-term off-balance sheet bank assets. 

inner tube

noun
  • An inflatable rubber tube inserted into the casing of a pneumatic tyre/tire. 

  • Synonym of swim ring 

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