glass harmonica vs glassichord

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. 

glassichord

noun
  • A 19th-century musical instrument made of glass plates that are struck by hammers or sticks. 

  • Synonym of glass harmonica 

  • Anything that produces a similarly pure continuous sound. 

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