pocket billiards vs wellspring

pocket billiards

noun
  • Synonym of pocket pool 

  • Any of a family of billiards games played on a specific class of billiards table, having six receptacles called pockets along the rails, in which balls are deposited as the main goal of play. 

wellspring

noun
  • A perennial source of anything; a fountainhead of supply or emanation; resource. 

  • The source of water for a stream, spring or well; a fountainhead; a wellhead. 

How often have the words pocket billiards and wellspring occurred in a corpus of books? (source: Google Ngram Viewer )