mimeograph vs photoengraving

mimeograph

noun
  • A machine for making printed copies using typed stencil, eventually superseded by photocopying. 

verb
  • To make mimeograph copies. 

photoengraving

noun
  • A process of transferring a photographic image onto a plate which is then etched and printed. 

  • A plate or reproduction made using this process. 

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