ducking stool vs tumbril

ducking stool

noun
  • A chair used to punish women, especially scolds, by ducking them in water. 

tumbril

noun
  • A kind of medieval torture device, later associated with a cucking stool. 

  • A cart used to carry condemned prisoners to their death, especially to the guillotine during the French Revolution. 

  • A cart which opens at the back to release its load. 

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