Main vs Sole

Main

name
  • A river in Northern Ireland, flowing into Lough Neagh. 

  • A river in southern Germany, flowing from Bavaria to the Rhine. 

  • A surname. 

Sole

name
  • A sea area, corresponding to the Sole Bank, to the north of FitzRoy 

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