Chinaman vs Ching

Chinaman

noun
  • A sailing ship of the 18th and 19th centuries engaged in the Old China Trade 

  • Synonym of Chinaperson, a Chinese person of either gender. 

Ching

name
  • A surname from Cantonese. 

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