Source : Webster's Revised Unabridged Dictionary (1913)

Bell metal \Bell" met`al\
   A hard alloy or bronze, consisting usually of about three
   parts of copper to one of tin; -- used for making bells.

   {Bell metal ore}, a sulphide of tin, copper, and iron; the
      mineral stannite.

Source : WordNet®

bell metal
     n : bronze with 3 or 4 parts copper to 1 part tin; used in
         making bells