saddlecloth vs underclothes

saddlecloth

noun
  • A blanket placed under a saddle, a saddle blanket. 

  • A cloth displaying a racehorse's number. 

underclothes

noun
  • clothes worn next to the skin and underneath outer clothing 

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