foremast vs topsail

foremast

noun
  • The mast nearest the bow, on a ship with more than one mast; the second-tallest mast on a full-rigged ship. 

topsail

noun
  • In a fore-and-aft-rigged sailing boat, the sail that is set above the gaff at the top part of the mast. 

  • A sail or either of the two sails rigged just above the course sail and supported by the topmast on a square-rigged sailing ship. 

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