bilboes vs custody

bilboes

noun
  • An iron bar fitting around the ankles of prisoners, and having sliding shackles. 

custody

noun
  • The state of being imprisoned or detained, usually pending a trial. 

  • Temporary possession or care of somebody else's property. 

  • The legal right to take care of something or somebody, especially children. 

  • An area under the jurisdiction of a custos within the Order of Friars Minor. 

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