clue vs galley proof

clue

noun
  • An object or a kind of indication which may be used as evidence. 

  • Information which may lead one to a certain point or conclusion. 

  • Insight or understanding ("to have a clue [about]" or "to have clue". See have a clue, clue stick) 

verb
  • To provide with a clue. 

  • To provide someone with information which he or she lacks (often used with "in" or "up"). 

galley proof

noun
  • A trial page or proof of continuous text that has not been divided into pages. 

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