artesian well vs wellspring

artesian well

noun
  • An aquifer in which water rises to the surface under its own hydrostatic pressure. 

  • A bore-hole in an artesian basin. 

wellspring

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

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

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