Birr vs Principality

Birr

name
  • A town in County Offaly, Ireland. 

  • A surname. 

  • A community in Middlesex Centre, Middlesex County, Ontario, Canada. 

  • A municipality in Aargau canton, Switzerland. 

Principality

name
  • Wales 

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