black bag vs black box

black bag

noun
  • The pouch or case traditionally carried by medical doctors, especially when making house calls, and containing medical instruments and supplies. 

  • A pouch or case containing burglary tools. 

  • A black plastic sack produced for the disposal of household waste. 

black box

noun
  • A flight recorder; the brightly colored cockpit voice recorders and flight data recorders in an aircraft designed to aid in determining the cause of an accident. 

  • A device used in phreaking that prevents the calling party from being billed for the call placed. 

  • A type of theater characterized by a lack of decoration or complex mechanisms. 

  • A theoretical construct or device with known input and output characteristics but unknown method of operation. 

  • Any similar device on motor vehicles, such as rail event recorders and ship trip recorders. 

verb
  • To focus on the inputs and outputs without worrying about the internal complexity. 

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