bowler vs cap of maintenance

bowler

noun
  • A bowler hat; a round black hat formerly popular among British businessmen. 

  • One who engages in the sport of bowling. 

  • The pitcher. 

  • A player selected mainly for his bowling ability. 

  • The player currently bowling. 

cap of maintenance

noun
  • A ceremonial cap of crimson velvet lined with ermine, worn or carried as a sign of nobility or special honour. 

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