Bartmann jug vs greybeard

Bartmann jug

noun
  • A bellarmine. 

greybeard

noun
  • A coarse earthenware vessel for holding liquor; a bellarmine. 

  • An old man. 

  • Any of the members of a group who have been there the longest, often implying experience. 

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