Pope's pear vs choke pear

Pope's pear

noun
  • Synonym of choke pear 

choke pear

noun
  • A metal torture device to be inserted into the body, consisting of a usually pear-shaped piece divided into spoon-like segments that can be spread apart by turning a screw. 

  • A kind of pear with a rough, astringent taste, difficult to swallow. 

How often have the words Pope's pear and choke pear occurred in a corpus of books? (source: Google Ngram Viewer )