attorn vs sign over

attorn

verb
  • To transfer one's obligations from a person to another person. 

  • To consent to the transfer of one's obligations as tenant under a lease to a new landlord. 

  • To acknowledge the jurisdiction of (a particular court) over one's dispute. 

sign over

verb
  • To transfer (property or rights) to somebody else by signing a document. 

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