Adam's flannel vs coachwhip

Adam's flannel

noun
  • The mullein (Verbascum thapsus). 

coachwhip

noun
  • Fouquieria splendens (ocotillo). 

  • A long whip used by the driver of a horse-drawn coach. 

  • Masticophis flagellum, a colubrid snake of North America. 

How often have the words Adam's flannel and coachwhip occurred in a corpus of books? (source: Google Ngram Viewer )