refractor vs terrestrial telescope

refractor

noun
  • A refracting telescope. 

  • anything which refracts light, heat or sound 

terrestrial telescope

noun
  • A telescope which, unlike most telescopes used for astronomical purposes, contains an arrangement of lenses presenting an erect (non-inverted) image to the observer, suitable for observation of objects on the Earth's surface. 

  • An astronomical telescope which is physically located on the surface of the Earth, as distinct from a telescope located in outer space. 

How often have the words refractor and terrestrial telescope occurred in a corpus of books? (source: Google Ngram Viewer )