dry point vs mezzotint

dry point

mezzotint

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. 

verb
  • To make such etchings 

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