cacolet vs palanquin

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. 

palanquin

noun
  • A covered type of litter for a stretched-out passenger, carried on four poles on the shoulders of four or more bearers, as formerly used (also by colonials) in eastern Asia. 

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