bass viol vs cello

bass viol

noun
  • A fretted, bowed, stringed musical instrument from the viola da gamba family. It occupies the bass range and is the lowest instrument in the family. Similar to (but smaller than) a cello. 

cello

noun
  • A large unfretted stringed instrument of the violin family with four strings tuned (lowest to highest) C-G-D-A and an endpin to support its weight, usually played with a bow. 

  • cellophane 

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