mower vs plower

mower

noun
  • A farm machine used in hay production (sickle mower, finger-bar mower). 

  • A lawnmower, a machine used to cut grass on lawns. 

  • A person who cuts grass. 

plower

noun
  • One who plows; one who works land with a plow. 

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