Definition of tocsin:
		
		
		(n) :
		
		a 
signal sounded by a bell or bells, especially an 
alarm
		 
								
				"1807: At half-past one, on the sounding of the tocsin (or bell of the public-house) about fifteen persons were collected, when the Rev. J. Bromley was called to the chair -- The Times, 23 Aug 1804, p.3 col. C"