brass instrument vs brass nail

brass instrument

noun
  • Any musical instrument whose tone is produced by vibration of the lips as the player blows into a mouthpiece (or tubular resonator). 

brass nail

noun
  • Used other than figuratively or idiomatically: see brass, nail. 

  • A prostitute. 

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