cacolet vs sedan chair

cacolet

noun
  • One of a pair of chairs or litters mounted on a pack animal (horse, mule, camel) 

  • A single litter mounted on a pack animal. 

sedan chair

noun
  • A small litter or palanquin, seating a single person, often borne on two poles and carried by two people. 

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