bell tower vs tintinnabulum

bell tower

noun
  • A tower in which a bell (or set of bells) is hung; a belfry. 

tintinnabulum

noun
  • A small clinking bell, particularly (historical) a small bell used to call monks to certain tasks. 

  • A set of bells or metal plates used as a musical instrument or as a toy. 

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