pair of compasses vs whorl

pair of compasses

noun
  • A tool for drawing accurate circles or arches, usually consisting of two arms joined at one end in such a way that the arms can be opened and closed; one of the arms is pointed at its free end while the other holds a pencil, pencil lead or some other implement for making marks. 

whorl

noun
  • Each circle, volution or equivalent in a pattern of concentric circles, ovals, arcs, or a spiral. 

  • A circle of three or more leaves, flowers, or other organs, about the same part or joint of a stem. 

  • A flywheel, a weight attached to a spindle. 

  • A volution, or turn, of the spire of a univalve shell. 

  • Any volution, as for example in the human ear or fingerprint. 

verb
  • To form a pattern of concentric circles. 

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