| 摘要 |
A disc with an aerodynamically shaped concave/convex surface and an inwardly turned rim has a central portion that includes a central circular depression in at least one transverse end surface thereof. The depression has a concave bottom and a right cylindrical side wall. In one embodiment of the invention, the central portion constitutes a readily removable and invertible plug so that the central depression may be arranged to face either inwardly or outwardly of the disc. In an alternative embodiment of the invention, the central portion is made integrally with the concave/convex surface and oppositely facing central depressions are formed on both (inner and outer) transverse end surfaces thereof. The disc is adapted to be spun by twirling an elongated wand the tip of which is in an inwardly or outwardly facing central depression of the disc, the disc being supported by the wand during such twirling. With the concave surface of the disc facing downwardly, twirling of the wand causes the disc to rotate, and after the disc is turning with sufficient speed a slight push of the wand in an upward direction will cause the disc either to hover or to sail through the air depending upon the magnitude and direction of the force applied by the wand and the speed of rotation of the disc. With the concave surface of the disc facing upwardly, either by inverting the central plug as in the first embodiment or by inverting the entire disc as in the second embodiment, a gyroscopic toy is provided. With the disc rotating and with its concave surface facing upwardly, the lower end of the wand the tip of which now is in the outwardly and downward facing depression can be placed on a flat surface where it will remain erect with the disc spinning on its upper end without any support for the wand. Should the wand be removed in this second mode of operation, the disc because of its aerodynamic configuration which generates a downward force, will descend and spin on the flat surface like a top. A feature of the invention is that both the central depression and the tip of the wand that coacts therewith are provided with low friction surfaces.
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