An overhead projector has been modified for stroboscopic illumination for the purpose of demonstrating the vibration of a string excited by a violin bow. The vibrational pattern is clearly delineated, as are differences caused by insufficient or excessive bow force. A regime of oscillation is noted at high bow force and low speed in which alternate waves are reflected from the bow and the bridge so that the vibration transmitted to the bridge is about an octave below the fundamental frequency of the string.