steamboat vs wherry

steamboat

noun
  • A boat or vessel propelled by steam power. 

  • Hot pot (Chinese dish). 

verb
  • To travel by steamboat. 

wherry

noun
  • A light ship used to navigate inland waterways. 

  • A flat-bottomed vessel once employed by British merchants, notably in East Anglia, sometimes converted into pleasure boats. 

  • A liquor made from the pulp of crab apples after the verjuice is extracted. 

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