brougham vs horse-drawn carriage

brougham

noun
  • A four-wheeled horse-drawn carriage, designed in 1839. It had an open seat for the driver in front of the closed cabin for two or four passengers. 

  • An automobile, a sedan without a roof over the driver's seat. 

horse-drawn carriage

How often have the words brougham and horse-drawn carriage occurred in a corpus of books? (source: Google Ngram Viewer )