Used to simulate effect of earth's rotation on winds, ocean currents or unattached objects such as rockets. As sphere is launched across surface of base, when it is static, sphere traces a straight line. As turntable is put in motion, centrifugal force launches the sphere which, though traveling in a straight line, leaves a curved trace on rotating surface. Size of curve is in direct ratio to speed of rotation. Each kit includes one 14" diam. base (with outer retaining trough) mounted on a turntable, and featuring a reusable "magic slate" type erasable trace recording surface, removable launcher, 5/8" diameter steel spheres.