cliffage vs usherdom

cliffage

noun
  • Cliffs, collectively. 

  • The right to quarry limestone from the cliffs of the Gower, or the payment charged for this right. 

usherdom

noun
  • Ushers, collectively. 

  • The office or position of an usher. 

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