handcuffs vs leg irons

handcuffs

noun
  • A fastening consisting of two metal rings, designed to go around a person's wrists, and connected by a chain or hinge. 

leg irons

noun
  • A fetter or shackle attached at the ankle. 

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