This advanced apparatus demonstrates both longitudinal and transverse wave motions. Consisting of a number of eccentric discs supporting a series of metal rods revolving on a handle, transverse waves are obtained. The handle is rotated to cause a series of cams to rotate which, in turn, cause a set of 16 vertical rods to rise and fall. Their motion follows that of a sine wave (vertical motion is caused by circular rotary motion). Transverse motion is visible by observing the tips of the rods (like a ripple in a water tank or a vibrating guitar string). Longitudinal waves are obtained from the bent rods. A scale placed behind the handle divides the rotary motion into degrees of rotational angle so that the relationship or 'phase' between the rotary and the vertical motions may also be studied.
