This Demonstration illustrates the normal vibrational modes of a drum head fixed along a circular edge. Each mode with elongation (in polar coordinates) is related to Bessel functions of the first kind, , where is the radial coordinate, the polar angle, and the time. Selecting the order, , determines the angular periodicity of the drum head. Selecting the zero of determines the number of antinodes along a radial line connecting the center and outer edge.