fire alarm vs tocsin

fire alarm

noun
  • An electromechanical or electronic bell, klaxon, chime, horn, speaker, strobe light or other device which warns people in a building of a possible fire or other condition requiring evacuation. 

  • The sound or other warning made by a fire alarm. 

  • An emergency response to a fire by the fire department with manpower and equipment. 

tocsin

noun
  • A bell used to sound an alarm. 

  • An alarm or other signal sounded by a bell or bells, originally especially with reference to France. 

How often have the words fire alarm and tocsin occurred in a corpus of books? (source: Google Ngram Viewer )