rajah vs viscount

rajah

noun
  • Any of various nymphalid butterflies of the genus Charaxes. 

  • a Hindu prince or ruler in India. 

viscount

noun
  • Any of various nymphalid butterflies of the genus Tanaecia. Other butterflies in this genus are called earls and counts. 

  • A member of the peerage, above a baron but below a count or earl. 

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