Spanish donkey vs wooden horse

Spanish donkey

noun
  • A torture device consisting of a very narrow vertical surface where the victim is supposed to sit with heavy objects attached to their feet. 

wooden horse

noun
  • Synonym of Spanish donkey: a torture device. 

  • A toy horse made of wood. 

How often have the words Spanish donkey and wooden horse occurred in a corpus of books? (source: Google Ngram Viewer )