pack horse vs plater

pack horse

noun
  • A horse used for carrying luggage. 

plater

noun
  • A horse that runs chiefly in selling plates; hence, an inferior racehorse. 

  • A device for depositing cells on a plate. 

  • A machine for calendering paper. 

  • Someone who plates metal. 

  • Someone who installs sheet metal and armour plating, particularly on trains, ships, tanks, and similar items. 

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