mower vs reaper

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. 

reaper

noun
  • A machine used to harvest crops. 

  • The recluse spider (Loxosceles and Sicarius spp.). 

  • One who reaps; a person employed to harvest crops from the fields by reaping. 

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