. ▁A ▁" ring ▁of ▁b ells " ▁is ▁a ▁set ▁of ▁four ▁to ▁twelve ▁or ▁more ▁b ells ▁used ▁in ▁change ▁ring ing , ▁a ▁particular ▁method ▁of ▁ring ing ▁b ells ▁in ▁patterns . ▁A ▁pe al ▁in ▁changing ▁ring ing ▁may ▁have ▁b ells ▁playing ▁for ▁several ▁hours , ▁playing ▁ 5 , 0 0 0 ▁or ▁more ▁patterns ▁without ▁a ▁break ▁or ▁repet ition . ▁They ▁have ▁also ▁been ▁used ▁in ▁many ▁kinds ▁of ▁popular ▁music , ▁such ▁as ▁in ▁AC / DC ' s ▁" H ells ▁B ells " ▁and ▁Met all ica ' s ▁" For ▁Wh om ▁the ▁Bell ▁T oll s ". ▁ ▁An cient ▁Chinese ▁b ells ▁▁ ▁The ▁ancient ▁Chinese ▁bronze ▁ch ime ▁b ells ▁called ▁b ian zh ong ▁or ▁z h ong ▁/ ▁z eng ▁( <0xE9> <0x90> <0x98> ) ▁were ▁used ▁as ▁poly ph onic ▁musical ▁instruments ▁and ▁some ▁have ▁been ▁dated ▁at ▁between ▁ 2 0 0 0 ▁and ▁ 3 6 0 0 ▁years ▁old . ▁Tun ed ▁b ells ▁have ▁been ▁created ▁and ▁used ▁for ▁musical ▁performance ▁in ▁many ▁cult ures ▁but ▁z h ong ▁are ▁unique ▁among ▁all ▁other ▁types ▁of ▁cast ▁b ells ▁in ▁several ▁respect s ▁and ▁they ▁rank ▁among ▁the ▁highest ▁achiev ements ▁of ▁Chinese ▁bronze ▁casting ▁technology . ▁However , ▁the ▁remarkable ▁secret ▁of ▁their ▁design ▁and ▁the ▁method ▁of ▁casting — known ▁only ▁to ▁the ▁Chinese ▁in ▁anti qu ity — was ▁lost ▁in ▁later ▁gener ations ▁and ▁was ▁not