Like paw prints in the snow, these precisely timed sparks leave a permanent series of tracks in the paper. The record becomes permanent as holes are sparked into the paper. Measurement of the intervals can be done anytime after the completion of the experimental run. The generator can be set on any one of five frequencies (60, 30, 20, 15 and 10 Hz). Since only a spark is coming from the moving object and it is not dragging any recording device, the frictional drag is nearly zero. Works particularly well on air tracks—the spark jumps from a wire on the glider, through the spark paper to the grounded track, leaving a mark for each electrical pulse. The spark generator is controlled by a manual pushbutton included.