mezzotint vs xylograph

mezzotint

verb
  • To make such etchings 

noun
  • A form of intaglio etching in which a metal plate is roughened evenly and then smoothed to bring out an image. 

  • An etching or print made using this method. 

xylograph

verb
  • To make a print from an engraving in wood. 

noun
  • A print taken from such an engraving. 

  • An engraving in wood or woodcut, especially one used in printing predating the Western tradition (14th c.). 

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