glass harmonica vs verrillon

glass harmonica

noun
  • The glass harp. 

  • A musical instrument composed of a series of spinning glass bowls, played with the fingers, invented by Benjamin Franklin. 

verrillon

noun
  • The glass harp: a musical instrument consisting of an array of glasses filled with varying amounts of water, played by rubbing one's fingers around the rims of the glasses. 

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