galley proof vs validation

galley proof

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

validation

noun
  • Something, such as a certificate, that validates something; attestation, authentication, confirmation, proof or verification. 

  • The process of identifying a new prisoner's gang affiliation. 

  • The process whereby others confirm the validity of one's emotions. 

  • The act of validating something. 

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