artesian well vs headspring

artesian well

noun
  • A bore-hole in an artesian basin. 

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

headspring

noun
  • A fountainhead; a source. 

  • A move in which the gymnast places both hands on the mat with the top of the head about 6 inches in front, pushes off with the hands while flipping the legs overhead, and lands on the feet. 

  • A basis or foundation. 

  • A spring that sits at the top of a mechanism, pushing the internal parts inward. 

verb
  • To perform a headspring. 

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