This gyro, very similar to the one designed by Prof. Maxwell, is designed to show that a gyroscope will always react at 90 degrees to an applied force. To show this the spindle of the heavy spinning wheel, which is pivoted at it's center of gravity, will follow an irregularly shaped object (in this case a Tracer Spiral).
With several turns of cord on the stem, pull gently to spin the top. The cord will release from the stem and the top will start following the "tracer spiral".