A loosely hanging string attached on one end to an eccentric on the shaft of a high speed motor and on the other to a small mass is made to spin rapidly. Unbalanced, the string starts to vibrate in a rapid and generally unpredictable fashion leaving a trace of its convolutions in space. These are recorded with a simple camera over a period of a second or two. The white lines indicate the limits of a given excursion of the string sideways. Since the string is seen by the camera to reside along these edges for a longer time than along motion in a transversal direction the edges appear better defined than the front of the vibration "envelope".