ACOUSTICS OF THE GLASS HARMONICA

Glass harmonicas or glass harps, consisting of sets of tuned glasses, were already popular in Europe when Benjamin Franklin designed an impr oved style of instrument that he called an armonica. The modes of a wi neglass resemble the flexural modes of a bell. Striking the glass exci tes a number of these modes, but rubbing the rim with a finger or bowi ng it radially with a violin bow generally excites a single mode. As t he player's finger moves around the rim of the glass, the nodes and an tinodes move with it, resulting in a pulsating sound.