Borstal vs Tower

Borstal

name
  • A suburb, formerly a village, in Rochester, Medway borough, Kent, England (OS grid ref TQ7366). 

Tower

name
  • A habitational surname.; Alternative form of Towers 

  • The Tower of London, especially seen as a place of imprisonment or punishment. 

noun
  • Denoting the system of weights used by the Saxon and Norman English kings in their minting of coins. 

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