Tapper 1 : (1) A bell or gong that sounds on receipt of a fire alarm box signal. See: Joker. (2) A bell or gong used to signal companies in and out of service
Ralph W. Burklin & Robert G. Purington, Fire Terms: A Guide to Their Meaning and Use, National Protection Association, Boston, MA 1980 USA. (Guide: Meaning and Use, Nat Prot Association Fr Srvc - Amer) {457}