hook and eye vs knag

hook and eye

noun
  • A matched hook and an eye (loop into which the hook can fit), used for fastening. 

knag

noun
  • A peg or hook for hanging something on 

  • A pointed rock or crag 

  • A small cask or barrel; a keg or noggin 

  • A knot in a piece of wood or the base of a branch 

  • A short spur or stiff projection from the trunk or branch of a tree, such as the stunted dead branch of a fir 

verb
  • To hang something on a peg 

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