Back vs Forth

Back

name
  • A settlement on the Isle of Lewis, Western Isles council area, Scotland (OS grid ref NB4840). 

  • A surname. 

Forth

name
  • A village in South Lanarkshire council area, Scotland (OS grid ref NS9453). 

  • A river in Scotland that flows for about 47 km (29 miles) from The Trossachs through Stirling to the Firth of Forth on the North Sea. 

  • A sea area that covers the Firth of Forth 

  • An imperative, stack-based high-level programming language, used mostly in control applications. 

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