Very light vs smoke signal

Very light

noun
  • A type of pyrotechnic flare used as a signal or temporary illumination. 

smoke signal

noun
  • A method of long-distance communication sometimes used in ancient and undeveloped societies, consisting of messages conveyed by means of columns or intermittent puffs of smoke. 

  • A message or sign sent by this method. 

  • An indirect message or indication, especially concerning a future event. 

  • A type of flare or combustion device sometimes used as a distress signal. 

How often have the words Very light and smoke signal occurred in a corpus of books? (source: Google Ngram Viewer )