crwth vs vielle

crwth

noun
  • An archaic stringed instrument associated particularly with Wales, though once played widely in Europe, and characterized by a vaulted back and enough space for the player to stop each of the six strings on the fingerboard. Played variously by plucking or bowing. 

vielle

noun
  • A medieval stringed instrument similar to a violin. 

  • The hurdy-gurdy. 

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