curbing vs fettering

curbing

noun
  • A row of curbstones; the material used to construct such a curb 

  • The damage caused to a wheel or tire by curbing (running the wheel or tire into or over a curb). 

fettering

noun
  • The act by which something is fettered or constricted. 

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