crossbar vs scaffolding

crossbar

noun
  • The top tube of a bicycle frame. 

  • The top of the goal structure. 

  • Any transverse bar or piece, such as a bar across a door, or the iron bar or stock which passes through the shank of an anchor. 

verb
  • To mark with a pattern of transverse bars. 

scaffolding

noun
  • A temporary modular system of tubes (or formerly wood) forming a framework used to support people and material in the construction or repair of buildings and other large structures. 

  • Source code etc. that is incomplete and serves as a basis for further development. 

  • Any framework or support. 

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