espy vs give someone the eye

espy

verb
  • To find out or observe (someone or something, especially if not easy to see) by spying or looking; to catch sight of; to see; to spot. 

  • To see (someone or something) without foreplanning or unexpectedly. 

give someone the eye

verb
  • To show flirtatious signs with one's eyes. 

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