garrotte vs iron collar

garrotte

verb
  • To execute by strangulation. 

  • To suddenly render insensible by semi-strangulation, and then to rob. 

noun
  • A cord, wire or similar used for strangulation. 

  • An iron collar formerly used in Spain to execute people by strangulation. 

iron collar

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