Blithe vs Slough

Blithe

name
  • A river in Staffordshire, England, which joins the River Trent. 

Slough

name
  • A town in east Berkshire, England (formerly Buckinghamshire), close to Heathrow Airport. 

  • A borough and unitary authority (Slough Borough Council) in Berkshire. 

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