Beschreibung:
<jats:p>Modern glass harmonicas have developed along two different lines: One type consists of a collection of wineglasses, which the player sets into vibration by moving a finger around the rim. The other type, called the armonica by its inventor Benjamin Franklin, consists of a series of glass bowls mounted on a horizontal shaft so that they rotate together. The vibrational modes of a glass harmonica are quite similar to those of a bell, the fundamental (2,0) mode determining the pitch. The tangential component of motion in this mode (which is 1/2 the normal component) is apparently excited by stick-slip coupling to the moving finger of the player. Simple theory predicts that the frequency will increase as t/r2, where r is the radius of the glass, and t is its thickness [T. D. Rossing, Phys. Teacher 28, 582–585].</jats:p>