equatorial vs semitropical

equatorial

adj
  • of, near, or relating to the equator 

  • perpendicular to the plane of a ring 

noun
  • A kind of telescope mounted so as to have two axes of motion at right angles to each other, one of them parallel to the axis of the Earth, and each carrying a graduated circle, one for measuring declination, and the other right ascension, or the hour angle, so that the telescope may be directed, even in the daytime, to any star or other object whose right ascension and declination are known. 

semitropical

adj
  • Intermediate between temperate and tropical. 

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