mason vs navvy

mason

noun
  • A bricklayer, one whose occupation is to build with stone or brick 

  • One who prepares stone for building purposes. 

  • A member of the fraternity of Freemasons. See Freemason. 

verb
  • To build stonework or brickwork about, under, in, over, etc.; to construct by masons 

navvy

noun
  • A laborer on a civil engineering project such as a canal or railroad. 

verb
  • To carry out physical labor on a civil engineering project. 

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