harshen vs inure

harshen

verb
  • To make, or to become harsh; render hard and rough. 

  • To render peevish, morose, or austere. 

inure

verb
  • To cause someone to become accustomed to something that requires prolonged or repeated tolerance of one or more unpleasantries. 

  • To take effect, to be operative. 

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