purser vs record keeper

purser

noun
  • The person responsible for handling the accounts on a ship, or for dealing with the passengers on a ship or aircraft. 

record keeper

noun
  • A keeper of records; one in charge of recordkeeping. 

  • A kind of trigonic quartz crystal, supposed to provide mystical insights into the future. 

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