peril vs warning bell

peril

noun
  • A situation of serious and immediate danger. 

  • An event which causes a loss, or the risk of a specific such event. 

  • Something that causes, contains, or presents danger. 

verb
  • To cause to be in danger; to imperil; to risk. 

warning bell

noun
  • A problematic or alarming aspect. 

  • A bell rung to warn people of a danger. 

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