Struck bronze disks, suspended from a circular wooden frame, have long been in use in East Asia, and the practice of sounding single disks in Indian temples still obtains. The ancient Roman discus, a metal plate with large central hole for suspension that served as a signal giver derives from such Eastern forebears.
The sound of beaten bronze or iron objects was believed in antiquity to cause specters to flee. Thus in Rome, after the annual visit to their former homes...