BLACK AND WHITE BANDS Museum of Science Boston, Massachusetts Stick a straight pin through the center of the circle. Spin the card on the pin and watch the straight bands turn into circles. been one peters the hinge for a traction vision As the disc spins, this persistence causes the image of the black and white bands to smear out into circles. natural color company, inc., boston, mass. 02130 P81959 POST CARD Plastichrome
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