Instrument to show the mode of vibration of a glass bell

Instrument to demonstrate vibration of a glass bell, first half 19th century. This instrument was designed to illustrate Ernst Chladni's work on the vibration of bells. A wine glass-shaped glass bell is set up on a mahogany base, above which is an eight-pointed star mounted on a vertical brass rod. Eight pith balls are suspended from the points of the star, so as to touch the inside rim of the glass. If the bell is held at one point of the rim and bowed at another, the motion of the pith balls indicates the vibration pattern of the bell.