caput vs headstock

caput

noun
  • The head. 

  • A knob-like protuberance or capitulum. 

  • The top or superior part of a thing. 

  • The council or ruling body of the University of Cambridge prior to the constitution of 1856. 

headstock

noun
  • A headframe. 

  • A beam that supports a bell. 

  • A part of a machine (such as a lathe or drill) that supports a rotating part 

  • A clamp that restrains a cow by the neck. 

  • The part of a lute-type string instrument, such as a guitar, that holds the tuning pegs or tensioning screws of the strings. 

  • A transverse structural member at the extreme end of a rail vehicle's underframe, also used on some bogies. 

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