reflecting telescope vs spotting scope

reflecting telescope

noun
  • A telescope which produces a magnified image by reflecting light through a series of mirrors housed in a tube, using a large curved mirror to gather the light and one or more additional mirrors to transmit the light to an eyepiece. 

spotting scope

noun
  • A compact high-power monocular telescope optimized for detailed observation of distant objects such as wildlife or the strike of a bullet on a target. 

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